UNIT ONE:

Unit Name INTRODUCTION TO NUTRITION

Introduction to Nutrition:
Meaning of terms
Nutrition: This is the science of food, the nutrients and other substances therein, their action,
interaction and their balance in relation to health and disease and the process by which the
organism ingests. Digests, absorbs, transports, utilizes and excretes food substances. Simple
terms, nutrition is the science of nourishing the body properly or the analysis of the effects of
food on the living organisms. Regardless of the definitions, the general agreement is that
nutrition is concerned with the way the body uses food until it is either build into the tissues or
excreted. Nutrition applies many principles including Chemistry,Biochemistry,Physiology and
Microbiology
It is also a multi displinary practice in that it includes:
 Agriculture
 Food technology
 Psychology
 Sociology
 Economics
 Religion
 Culture
 Communication.
Food: Refers to edible substance from animal or plant substance consisting of nutritive
components such as [mention all the nutrients] which when ingested and assimilated through
digestion release energy, causes growth, maintenance, promote health body and sustains life. It
is the group of edible substances which provide energy to the living beings, repairs the old
tissues, and build the new tissues.
Diet: It refers to the quantity [amount] and type of food and drinks consumed by a person
from day to day. It also refers to a regimen of food intake planned to meet specific
requirements of the individual, including or excluding certain foods. For example bland diet: a
diet free from any irritating or stimulating food. High fat diet, gluten free diet, acid-ash diet,
alkali-ash diet, high fibre diet, high protein diet, low fibre diet
Nutrients:
These are substances obtained from food and are used in the body to provide energy and
structural materials and to regulate growth, maintenance and repair of the body tissue. They
include carbohydrates. protein, vitamins, minerals. Fats and water. They are classified as:
 Macro-nutrients: These are nutrients needed by the body in large amounts and they
include carbohydrates, proteins and fat. They form the bulk of the diet and supply all the
energy needed by the body.
 Micro-nutrients: These are nutrients needed in small amounts for a variety of body
functions and processes. They include the vitamins and minerals.
Essential nutrients; These are nutrients that must be obtained from food because the body
cannot make them/synthesize the in sufficient amounts to meet the body’s physiological needs.
Examples: all minerals and vitamins, nine out of twenty amino acids, linoleic and linolenic
fatty acids,
Nutritional status: This refers to the condition of health of an individual as influenced the
intake and utilization of nutrients.
Malnutrition:This refers to any condition caused by an excess or deficient of energy or
nutrient intake or by an imbalance of nutrients, It is as a result of an imbalance between
dietary intake and requirements. There are single nutrient deficiencies, and imbalance of two
or more required nutrients.
Good/normal nutrition:
This refers to a sufficiency of nutrients intake that affords the highest level of wellness i.e
maintains normal growth and development, normal reproduction, optimum activity, resistance
to infections, ability to repair body injury etc.
Under nutrition: This refers to a deficiency of energy or nutrients. Under nutrition can be
categorized as primary deficiency that is caused by lack of foods such as protein energy
malnutrition (PEM), kwashiorkor, marasmus scurvy or as secondary deficiency that is caused
by something other than diet such as presence of a disease such as measles. A disease
condition reduces absorption, accelerates excretion or even causes destruction of nutrients.
Excess alcohol consumption and inborn errors of metabolism are also secondary causes of
undersnutition.
Over nutrition: This refers to excess intake of energy or other nutrients. It is common among
the affluent population and occurs mainly in the form of overweight and obesity and their
health related problems e.g. diabetes, hypertension etc.
Health: This refers to a state of complete physical, mental and social well-being and not
merely the absence of disease.

Classification of food
Classification of food can be based on the following criterias
1. Classification by origin:
 Foods of animal origin
 Foods of vegetable origin
2. Classification by chemical composition:
 Proteins
 Fats
 Carbohydrates
 Vitamins
 Minerals
3. Classification by predominant function
 Body building foods [proteins], for example: meat, milk, poultry, fish, eggs, pulses etc
 Energy giving foods [carbohydrates] for example: cereals, sugars, fats, oils etc.
 Protective foods [vitamins and minerals], for example vegetables, fruits, milk, etc

Development of nutrition as a science

The history of the study of food as medicine reveals centuries of discovery and development of
nutrition careers.
Although modern science and the latest discoveries in biology, medicine and health inform
today’s field of nutrition and diet, people have been investigating the very real link between
food and health for much longer than you may think.
In 400 B.C. the Greek physician Hippocrates, the “Father of Medicine” said, “Let thy food be
thy medicine and thy medicine be thy food.” Hippocrates realized that food impacts a person’s
health, body and mind to help prevent illness as well as maintain wellness.
In Hippocrates’ Greece, as well as across pre-modern Europe and Asia since ancient times,
foods were used to affect health. For instance, the juice of liver was squeezed on the eye to
treat eye diseases, connected to Vitamin A deficiency. Garlic was used to cure athlete’s foot,
and eating ginger was thought to stimulate the metabolism.
In 1747, a British Navy physician, Dr. James Lind, saw that sailors were developing scurvy, a
deadly bleeding disorder, on long voyages. He observed that they ate only nonperishable foods
such as bread and meat.
Lind’s experiment fed one group of sailors salt water, one group vinegar, and one group limes.
Those given limes didn’t develop scurvy. And although Vitamin C wasn’t discovered until the
1930s, this experiment changed the way physicians thought about food, creating a market for
nutrition careers.
Scientific Developments in Nutrition
During the Enlightenment and into the Victorian age, scientific and medical development
increased exponentially. The concept of metabolism, the transfer of food and oxygen into heat
and water in the body, creating energy, was discovered in 1770 by Antoine Lavoisier, the
“Father of Nutrition and Chemistry.” And in the early 1800s, the elements of carbon, nitrogen,
hydrogen and oxygen, the main components of food, were isolated and soon connected to
health.
Work in the area of the chemical nature of foods—carbohydrates, fats and proteins—was done
by Justus Liebig of Germany, and led to research in the area of vitamins in the early 20th
century. In 1912, a Polish doctor, Casimir Funk, coined the term “vitamins” as essential factors
in the diet. The term vitamin—first called “vitamine”—comes from “vital” and “amine,”
because vitamins are required for life and they were originally thought to be amines—
compounds derived from ammonia.
In 1912, E.V. McCollum, a U.S. Department of Agriculture researcher at the University of
Wisconsin, began using rats instead of humans in his experiments rather than cows and sheep.
He found the first fat-soluble vitamin, Vitamin A, and discovered that rats were healthier when
they were fed butter rather than lard, as butter contains more Vitamin A. Other diseases were
linked to vitamin deficiencies, such as beri-beri, resulting from a lack of Vitamin B, and
rickets, brought on by a lack of Vitamin D.
The Growth of the Health Products Industry
Many other vitamins were discovered and isolated in the early 20th century, and the concept of
supplementing health with vitamins was born. The first vitamin pills were marketed in the
1930s, and created a new industry around science-based health products. In October of 1994,
the Dietary and Supplement Health and Education Act was approved by Congress. It sets forth
what can and cannot be said about nutritional supplements without prior Food and Drug
Administration (FDA) review, showing the impact of this industry.
Dietitians and nutritionists first worked in hospitals in the late 19th century as the role of good
nutrition in health began to be accepted. In the United States, the Public Health Service began
including dietitians in PHS Hospital staffs in 1919 after World War I, to help monitor and
improve the health of World War I veterans, and became increasingly involved in the nation’s
health care system and beyond, into the private sector.
As nutrition and dietitian programs started to become more prevalent, nutrition careers and
dietitian jobs became more popular. Dietitians are registered with the American Dietetic
Association and are only able to use the title “dietitian” when they have met strict, specific
educational and experiential prerequisites and passed a national registration examination. The
title “nutritionist” is protected and designated by many but not all states in the United States.
Traditionally, dietitians work in hospitals, schools and prisons, and nutritionists more often
work in private practice, in education and research, although there is some overlap between the
two.
As we become increasingly aware and concerned about how nutrition affects our health, the
fields of nutrition and alternative medicine have seen unprecedented growth and expansion.
This continuing demand has fueled increasing nutrition jobs growth and has provided more
career opportunities than ever. College distance-learning and online nutrition programs are a
great way to explore this unique field with a distinguished and ancient pedigree.
Development of nutrition as a science; Basic principles of human nutrition; Recommended
dietary standards (RDA, RDI).
Diet Planning Principles
Diet planners have developed several ways to select foods. Whatever plan or combination of
plans they use, they keep in mind the following six basic diet planning principles:
1. Adequacy: An adequate diet should provide enough energy band enough of all the other
nutrients to meet the needs of a healthy people. For example, a person whose diet fails to
provide enough iron-rich foods may develop the symptoms of iron deficiency Anemia. The
same is true for all other nutrients.
2. Balance: This entails providing foods of a number of types in proportions to each other,
such that foods rich in some nutrients do not crowd out of the diet foods that are rich in other
nutrients. The art of balancing the diet involves using enough of each type of food but not too
much of each.
3. Calorie (energy) control: This principle involves the management of food energy intake.
The key to controlling energy intake is to select foods of high nutrient density.
4. Nutrient density: Part of the secret to eating well without overeating is to select foods that
deliver the most nutrients for the least energy. Nutrient density is a measure of nutrients a food
provides relative to the energy it provides. The more nutrients and fewer kcalories, the higher
the nutrient density.
5. Moderation: Foods rich in fat and sugar provide enjoyment and energy, but relatively few
nutrients. In addition, they promote weight gain when eaten in excess. A person practicing
moderation would eat foods rich in fat and sugars only on occasion and would regularly select
foods low in fat and sugar, a practice that automatically improves nutrient density. The
principle of moderation involves providing enough but not too much of a dietary constituent.
6. Variety: A diet may have all the virtues described above and still lack variety, if a person
eats the same foods day after day, people should vary their choices within each class of foods
from day to day, for at least three reasons. First, different foods in the same group contain
different arrays of nutrients. Second, no food is guaranteed entirely free of constituents that,
the excess, could be harmful. Third, as the adage goes, variety is the spice of life.
Diet planning guides:
To plan a diet that achieves all the dietary ideals outlined above, a planner needs not only
knowledge but tools. These tools include:
Dietary standards
Knowledge of the nutritive content of a diet is meaningless unless it be compared to some
standards. This lead to the development of dietary standards which serve as reference value
for intakes of essential nutrients that will maintain health in practically all healthy individuals.
Dietary standards are guidelines that help us understand how much of a particular
nutrient is needed by a healthy human being. These are amounts of essential nutrients
considered sufficient to meet the physiological needs of practically all healthy persons in a
specified group and food sources of energy needed by members of the group. These figures
are derived from compilation of experimental studies designed to determine the nutrient
requirements of human beings. Quantitatively, dietary standards are not requirements but
rather are estimates of reasonable levels of nutrients intake that should support normal function
in most healthy people. Dietary standards are obtained by:
 Survey of food intake of large numbers of apparently healthy individuals
 Surveys that include both food intake and nutritional status
 Controlled metabolic experiments (with limited number of individuals)
 Relevant studies on several species of animals.
Most developed countries have developed their own nutrient standards and these differ slightly
for individual nutrients partly because populations, environmental conditions and available
food supplies differ. The following are some of the different dietary standards for some
countries.
Recommended dietary allowances (rda).
These standards were developed for use i9n America. They represent quantities of nutrients to
meet known nutritional needs of practically all healthy people. Allowances refer to the amount
of nutrients to be actually consumed.
Recommended nutrient intakes (rni)
This is the Canadian own version of the RDA. It estimates nutrients needed to support good
health.
Safe intake of nutrients (sin)
These dietary standards were developed by the FOOD and Agriculture Organization (FAO)
and the World Health Organization (WHO).
Recommended intake of nutrients (rin)
These standards were developed for use in the United Kingdom (UK)
Uses of rda
 1. Evaluating the adequacy of the national food supply, setting goals for food production
2. Setting standards for menu planning for publicly funded nutritional programs e.g.
school feeding programs.
3. Establishing nutrition policy for public assistance, nursing homes and institutions
4. Interpreting the adequacy of diets in food consumption studies
5. Developing materials for nutrition education
6. Setting patterns for normal diets in hospital
7. Establishing labeling regulations
8. Setting guidelines for formulation of new products or the fortification of specific foods
Limitation and misuse of rda.
1. They are complex for direct use by consumers.
2. They do not state ideal or optimal level of intakes
3. Allowances for some age categories e.g. adolescents and elderly ar5e based on limited
data.
4. Data on food content of some nutrients especially the trace minerals are limited
5. They may not apply to sick people.

MACRONUTRIENTS

Macronutrients- Carbohydrates
Carbohydrates are the most abundant organic compounds in the universe. They include the
structural parts of plants in the form of cellulose as well as stores of starches and sugars. The
sun is the ultimate source of energy for living organisms. By an exceedingly complex process
known as photosynthesis, the energy of the sun is utilised by chlorophyll (the green colouring
matter in leaves) to synthesize carbohydrate from carbon dioxide in the air and water from the
soil. This is probably the most important reaction for the continuance of life because the
energy stored in the leaves, stems, roots and seeds is used in turn by animal species

6 CO2 + 6 H2O + light energy = C6H12O6 + 6 O2.

With regard to dietary significance, starches and sugars account for more than half of the
caloric intake around the world.
COMPOSITION
Carbohydrates are simple sugars or polymers such as starch that can be hydrolysed to simple
sugars by the action of digestive enzymes or by heating with dilute acids. Like thousands of
organic compounds, they contain carbon, hydrogen and oxygen. Generally, but not always, the
hydrogen and oxygen are present in the proportion to form water; hence the term
carbohydrate. However, other compounds such as acetic acid (C 2H4O2) and lactic acid
(C3H6O3) that are not carbohydrates, also contain hydrogen and oxygen in the same proportions
as water.
CLASSIFICATION, DISTRIBUTION AND CHARACTERISTICS

Carbohydrates are classified as:

 Monosaccharides or simple sugars
 Disaccharides or double sugars
 Polysaccharides, which include many molecules of simple sugars
MONOSACCHARIDES: These are compounds that cannot be hydrolyzed to simpler
compounds. Although naturally occurring simple sugars may contain 3 to 7 carbon atoms.
Glucose, galactose, fructose, and mannose have the same empirical formula, C 6H12O6. They
differ in the arrangement of the groupings about the carbon atoms and are distinctive in their
physical properties, such as solubility and sweetness.
Glucose, also known as dextrose, grape sugar, or corn sugar, is somewhat less sweet than cane
sugar and is soluble in hot or cold water. It is found in sweet fruits such as grapes, berries, and
oranges and in some vegetables such as sweet corn and carrots. It is prepared commercially as
corn syrup or in its crystalline form by the hydrolysis of starch with acids. Glucose is the chief
end product of the digestion of the disaccharides and polysaccharides, it is the form of
carbohydrate circulating in the blood and is the carbohydrate utilised by the cell for energy.

Fructose (levulose or fruit sugar) is a highly soluble sugar that does not readily crystallise. It is
much sweeter than cane sugar and is found in honey, ripe fruits, and some vegetables. It is also
a product of the hydrolysis of sucrose.

Galactose is not found free in nature, its only source being from the hydrolysis of lactose.
Mannose is of limited distribution in foods and of little consequence in nutrition. Ribose,
xylose, and arabinose are three pentoses that do not occur free in nature but are constituents of
pentosans in fruits and the nucleic acids of meats. Ribose is of great physiologic importance as
a constituent of riboflavin, a B complex vitamin, and of ribonucleic acid (RNA) and
deoxyribonucleic acid (DNA). It is rapidly synthesized by the body and is not a dietary
essential.
DISACCHARIDES

Disaccharides, or double sugars, result when two hexoses are combined with the loss of one
molecule of water, the empirical formula being Cl2H22Ol1.
Characteristics
They are water soluble, diffusible, and crystallisable and vary widely in their sweetness. They
are split to simple sugars by acid hydrolysis or by digestive enzymes.

Sucrose is the table sugar with which we are familiar and is found in cane or beet sugar, brown
sugar, sorghum, molasses, and maple sugar. Many fruits and some vegetables contain small
amounts of sucrose.

Lactose, or milk sugar, is produced by mammals and is the only carbohydrate of animal origin
of significance in the diet. It is about one sixth as sweet as sucrose and dissolves poorly in cold
water. The concentration of lactose in milk varies from 2 to 8 per cent, depending upon the
species of animal.

Maltose, or malt sugar, does not occur to any appreciable extent in foods. It is an intermediate
product in the hydrolysis of starch. Maltose is produced in the malting and fermentation of
grains and is present in beer and malted break- fast cereals. It is also used with dextrins as the
source of carbohydrate for some infant formulas.

POLYSACCHARIDES

Polysaccharides (C6HlOO5) n' are complex compounds with a relatively high molecular weight.

Characteristics

They are amorphous rather than crystalline, are not sweet, are insoluble in water, and are
digested with varying degrees of completeness. Starches, dextrins, glycogen, and several
indigestible carbohydrates are of nutritional interest.
Starch is the storage form of carbohydrate in the plant and a valuable contributor to the energy
content of the diet. It consists of numerous glucose units linked in two types of chains: (1)
amylose, comprised of long, straight chains of glucose, and (2) amylopectin, consisting of
shorter, branched chains of glucose. The starch granules are encased in a cellulose-type wall
and are distinctive in size and shape for each source. When starch is cooked in moist heat, the
granules absorb water and swell, and the walls of the cell are ruptured, thus permitting more
ready access to the digestive enzymes. Amylopectin has colloidal properties so that thickening
of a starch-water mixture occurs when heat is applied.
Dextrins are intermediate products in the hydrolysis of starch and consist of shorter chains of
glucose units. Some dextrins are produced when flour is browned or bread is toasted.

Glycogen, the so-called "animal starch," is similar in structure to the amylopectin of starch, but
contains many more branched chains of glucose. It is rapidly synthesized from glucose in the
liver and muscle.

INDIGESTIBLE POLYSACCHARIDES (FIBRES or ROUGHAGES)

Fibres are the structural parts of plants. Most fibres are polysaccharides, but starch is not one
of them; in fact, fibres are often described as nonstarch polysaccharides.
Nonstarch polysaccharides include:
cellulose, hemicelluloses, pectins, gums, and mucilages.
Fibres also include some nonpolysaccharides such as:
lignins, cutins, and tannins.
Even though most are polysaccharides, fibres differ from starches in that human digestive
enzymes cannot break down the bonds between their monosaccharides. The bacteria of the GI
tract can break some fibres down, however, and this is important to digestion and to health.

Cellulose: Cellulose is the most abundant organic compound in the world, comprising at least
50 per cent of the carbon in vegetation. This is the primary constituent of plant cell walls and
therefore occurs in all vegetables, fruits, and legumes. Like starch, cellulose is composed of
glucose molecules connected in long chains. Unlike starch, however, the chains do not branch,
and the bonds linking the glucose molecules together resist digestion by human enzymes.
Ruminants are able to utilise cellulose for energy because of the presence of specific enzymes
in the rumen

Hemicelluloses: These are the main constituents of cereal fibres. They are composed of
various monosaccharides backbones with branching-side chains of monosaccharides. The
many backbones and side chains make the hemicelluloses a diverse group; some are soluble,
while others are insoluble. Soluble fibres occur in higher concentration in fruits, oats, barley,
and legume. They have the ability to hold water and form gel therefore in the body they delay
the stomach emptying and transit of chime through the intestines, delay glucose absorption and
lower blood cholesterol levels. Insoluble fibre, found in higher concentration in vegetables,
wheat and cereals. In the body, insoluble fibres accelerate transit time of chime through the
intestines, increase fecal weight and slow starch breakdown and delay glucose absorption into
the blood *In hemicelluloses, the most common backbone monosaccharides are xylose,
mannose, and galactose; the common side chains are arabinose, glucuronic acid, and galactose.

Pectins: All pectins consist of a backbone derived from carbohydrate with side chains of
various monosaccharides. Commonly found in vegetables and fruits (especially citrus fruits
and apples), pectins may be isolated and used by the food industry to thicken jelly, keep salad
dressing from separating, and otherwise control texture and consistency. Pectins can perform
these functions because they readily form gels in water.

Gums and mucilages: When cut, a plant secretes gums from the site of the injury. Like the
other fibres, gums are composed of various monosaccharides and their derivatives. Gums such
as gum arabic are used as additives by the food industry. Mucilages are similar to gums in
structure; they include guar and carrageenan, which are added to foods as stabilisers.

Lignin: This nonpolysaccharide fibre has a three-dimensional structure that gives it strength.
Because of its toughness, few of the foods that people eat contain much lignin. It occurs in the
woody parts of vegetables such as carrots and the small seeds of fruits such as strawberries-

Other Classifications of Fibres: Scientists classify fibres in several ways. The previous
paragraphs classified them according to their chemical properties. Fibres can also be classified
according to their solubility. Some researchers classify fibres according to other physical
properties that affect their function and nutrient absorption. Physical properties of fibres
include:
 Water-holding capacity: the capacity to capture water like a sponge, swelling and
increasing the bulk of the intestines' contents.
 Viscosity: the capacity to form viscous, gel-like solutions
 Cation-exchange capacity: the ability to bind minerals.
 Bile-binding capacity: the ability to bind to bile acids.
 Fermentability: the extent to which bacteria in the GI tract can break down fibres to
fragments that the body can use...

Several indigestible polysaccharides have useful properties in food processing. Pectins found
in ripe fruits, have the ability to absorb water and to form gels, a property utilised in making
fruit jellies. Agar is obtained from seaweed and is useful for its gelling properties. Carrageen
(Irish moss) and alginates from seaweed are often used to enhance the smoothness of foods
such as ice cream and evaporated milk.

Functions of Carbohydrates

1. Energy Source: Each gram of carbohydrate when oxidized yields, on the average, 4
calories. Some carbohydrate in the form of glucose will be used directly to meet immediate
tissue energy needs, a small amount will be stored as glycogen in the liver and muscles, and
some will be stored as adipose tissue for later conversion to energy. Glucose is the sole form of
energy for the brain and nervous tissue and must be available moment by moment for the
functioning of these tissues. Any failure to supply glucose, or the oxygen for its oxidation, is
rapidly damaging to the brain.

Glycogen is the storage form of carbohydrate in the body. At any given time about 100 gm
glycogen can be stored in the liver and is available to replenish the glucose level of the blood.
Cardiac, smooth, and skeletal muscles contain about 200 to 250 gm glycogen that is instantly
available within the muscle but is not available for regulation of the blood sugar level.
Together, muscle and liver glycogen if completely used could meet no more than half the day's
energy need.

2. Protein-sparing action: The body will use carbohydrate preferentially as a source of energy
when it is adequately supplied in the diet, thus sparing protein for tissue building. Since
meeting energy needs of the body takes priority over other functions, using adipose and protein
tissues will make up any deficiency of calories in the diet.
3. Regulation of fat metabolism: Some carbohydrate is necessary in the diet so that the
oxidation of fats can proceed normally. When carbohydrate is severely restricted in the diet,
fats will be metabolised faster than the body can take care of the intermediate products. The
accumulation of these incompletely oxidised products leads to ketosis.

Carbohydrate must be almost completely lacking in the diet for acidosis to occur under normal
conditions, but it is common in uncontrolled diabetes mellitus.

4. Carbohydrates impart flavour and sweetness to food

5. Role in gastrointestinal function: Several regulatory functions have been

attributed to lactose.
 Lactose promotes the growth of desirable bacteria in the small intestine. Some of these
bacteria are useful in the synthesis of certain B complex vitamins.
 Lactose also enhances the absorption of calcium. It is undoubtedly no accident of
nature that milk, which is the out- standing source of calcium, is also the only dietary
source of lactose.
 Cellulose, hemicellulose, and pectins yield no nutrients to the body. These indigestible
substances aid in the stimulation of the peristaltic movements of the gastrointestinal
tract, and by absorbing water give bulk to the intestinal contents and reduces the length
of time foods wastes in the colon.

6. Carbohydrate in body compounds: structurally, carbohydrate accounts for a very small part
of the weight of the body. Nevertheless, monosaccharides are vitally important constituents of
numerous compounds that regulate metabolism. Among these are:
  Glucuronic acid, which occurs in the liver and is also a constituent of a number of
mucopolysaccharides.

 Glucuronic acid in the liver combines with toxic chemicals and bacterial by-products
and is thus a detoxifying agent.
 Hyaluronic acid, a viscous substance that forms the matrix of connective tissue.
 Heparin, a mucopolysaccharide, a substance that prevents the clotting of blood.
 Chondroitin sulphates found in skin, tendons, cartilage, bone, and heart valves. "
 Immunopolysaccharides as part of the body's mechanism to resist infections.
 Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), the compounds that possess
and transfer the genetic characteristics of the cell.
 Galactolipins as constituents of nervous tissue.
 Glycosides as components of steroid and adrenal hormones.

DIGESTION AND ABSORPTION

Digestion
The ultimate goal of digestion and absorption of sugars and starches is to dismantle them into
small molecules that the body can absorb and use-chiefly glucose. The large starch molecules
require extensive breakdown; the disaccharides need only to be hydrolysed once. This is
accomplished by enzymes of the digestive juices and yields these end products:

The initial splitting begins in the mouth; the final splitting and absorption occur in the small
intestine; and conversion to a common energy currency (glucose) takes place in the liver. .

The Processes of Digestion and Absorption

When a person eats foods containing starch, various enzymes hydrolyse the long chains to
shorter chains, the short chains to disaccharides, and, finally, the disaccharides to
monosaccharides. This process begins in the mouth.

In the Mouth: In the mouth, vigorous chewing of high-fibre foods slows eating and stimulates
the flow of saliva. The salivary enzyme amylase starts to work hydrolysing starch to shorter
polysaccharides and to maltose. Because food is in the mouth for only a short time, very little
digestion takes place there. Salivary amylase does not act upon raw starch but pancreatic
amylase hydrolyses both raw and cooked starch to dextrins and, in turn, to maltose. Cooked
starch is more rapidly hydrolysed because the cell walls have been ruptured and the enzymes
have more ready access to the starch granules.

In the Stomach: The swallowed bolus mixes with the stomach's acid and protein-digesting
enzymes, and these digest the salivary enzyme amylase. Thus amylase is removed from the
scene before its job of starch digestion is completed. To a small extent, the stomach's acid
continues breaking starch down, but its juices contain no enzymes to digest carbohydrate.
Fibres linger in the stomach and delay gastric emptying, thereby providing a feeling of fullness
and satiety.

In the Small Intestine: The small intestine performs most of the work of carbohydrate
digestion. A major carbohydrate-digesting enzyme, pancreatic amylase, enters the intestine via
the pancreatic duct and continues breaking down the polysaccharides to shorter glucose chains
and disaccharides. The final step takes place on the outer membranes of the intestinal cells.
There, specific enzymes dismantle specific disaccharides:

Starch amylase Glucose

Sucrose sucarse Glucose + fructose

Maltose maltase Glucose + glucose

Lactose lactase Glucose + galactose

In the Large Intestine: Within one to four hours after a meal, all the sugars and most of the
starches have been digested. The small fraction of starches that escapes digestion and
absorption in the small intestine is known as resistant starch. Because resistant starches remain
in the large intestine, they promote bowel movements as fibres do, but unlike fibres, they do
not lower blood cholesterol. Like resistant starches, fibres in the large intestine attract water,
which softens the stools for passage without straining.
Fibre: Cellulose and hemicellulose cannot be hydrolysed by enzymes of the human digestive
tract, therefore yield no energy, and are excreted in the faeces. Tough fibres including seeds,
skins, and structural parts of plant foods are broken into smaller particles, whereas the more
tender fibres of young plants may be partially disintegrated by bacterial action within the large
intestine. The cooking of foods also softens fibres and partially disintegrates them.

Available carbohydrate: The total carbohydrate values reported in tables of food composition
include not only the fully digestible starches and sugars but also nondigestible components
such as cellulose, hemicellulose, and pectins. Thus, the amount of carbohydrate actually
available to the body is the difference between the total carbohydrate and the amount of fibre
that is present. The carbohydrate of refined flours and cereals, sugars, and sweets is
completely, or almost completely, digested, whereas that from fibrous vegetable fruits with
seeds and whole-grain cereals and flours is somewhat less completely digested.

Absorption into the Bloodstream

Glucose is unique in that it can be absorbed to some extent through the lining of the mouth, but
for the most part, all nutrient absorption takes place in the small intestine. The
monosaccharides traverse the cells lining the small intestine by active transport and are washed
away in the circulating blood. The blood then circulates through the liver, whose cells take up
fructose and galactose and convert them to other compounds, most often to glucose. Thus all
disaccharides not only provide at least a glucose molecule directly, but they can also provide
another one indirectly through the con-version of fructose and galactose to glucose.

Absorption

Glucose, fructose, and galactose are absorbed into the portal circulation and are carried to the
liver. Glucose and galactose can be absorbed by passive diffusion with a carrier as an
intermediary as long as the concentration at the luminal surface is greater than that in the
circulation. When the concentration in the circulation exceeds that at the luminal surfaces, then
an active transport through the sodium pump and a mobile carrier system is required. Most
absorption Occurs from the jejunum. When the concentration of sugar in the intestine is great,
the need for carriers to ferry sugars across the epithelial cells may exceed the numbers present;
hence, some sugars will move along the tract to carrier sites in the ileum. The rate of
absorption is about equal for galactose and glucose, whereas fructose is absorbed about half as
rapidly. Mannose and xylose are poorly absorbed, indicating a high level of selectivity at the
absorption sites.
Health benefits of starch and fibres

PromotingWeight Control. Foods rich in complex carbohydrates tend to be low in fat and
added sugars and can therefore promote weight loss by providing less energy per bite. They
also provide satiety and delay hunger. Several studies have found that people who eat a high-
carbohydrate breakfast take in fewer kcalories at later meals and snacks than people who eat
low-fibre or high-fat breakfasts do. To use fibre in a weight-loss plan, select fresh fruits,
vegetables, legumes, and whole-grain foods. High-fibre foods not only add bulk to the diet, but
also are economical and nutritious. (A note of caution, though: on baked goods, read the label.

Reduced risk of Heart Disease: High-carbohydrate diets are associated with low blood
cholesterol and a low risk of heart disease. Such diets are low in animal fat and cholesterol and
high in soluble fibres and vegetable proteins, which are a1l factors associated with a lower risk
of heart disease. Foods rich in soluble fibres (such as oat bran, barley, and legumes) lower
blood cholesterol by binding with bile acids, thus increasing their excretion. With fewer bile
acids available in the intestine, fewer lipids are absorbed. More importantly, the binding
prevents bile acids from being returned to the liver where they can be reused to make
cholesterol. Consequently, the liver must use its cholesterol to make new bile acids. In
addition, the bacterial by-products of fibre digestion in the colon also inhibit cholesterol
synthesis in the liver. The net result is lower blood cholesterol. Several researchers have
speculated that fibre may also exert its effect by displacing fats in the diet. Even when dietary
fat is low, however, high intakes of soluble fibres exert a separate and significant cholesterol-
lowering effect. In other words, a high-fibre diet helps to prevent heart disease independent of
fat intake.

Protection against Cancer: A high-carbohydrate diet, especially one that includes plenty of
green and yellow vegetables and citrus fruits, protects against some types of cancer. Again, it
is unclear whether the protection derives from the fibre, the vitamins, or phytochemicals.
Populations consuming high-fibre diets generally have lower rates of colon cancer than similar
populations consuming low-fibre diets. Fibre may help prevent colon cancer by diluting,
binding and rapidly removing potentially cancer-causing agents from the colon. Alternatively,
the protective effect may be due to the fermentation of resistant starch and fibre in the colon,
which lowers the pH. A lower pH in the colon is associated with decreased colon cancer risks.

Low rate of diabetes and improved glucose control in Diabetes: Populations eating high-
carbohydrate diets often have low rates of diabetes, most likely because such diets are low in
fat. High-carbohydrate, low- fat diets help control weight, and this is the most effective way to
prevent the most common type of diabetes (type 2). Furthermore, when soluble fibres trap
nutrients and delay their transit through the GI tract, glucose absorption is slowed, and this
helps to prevent the glucose surge and rebound that seem to be associated with diabetes onset.
High-fibre foods play a key role in reducing the risk of diabetes.

Enhancing GI Health: Dietary fibres enhance the health of the large intestine. The healthier
the intestinal walls, the better they can block absorption of unwanted constituents. Insoluble
fibres such as cellulose (as in cereal brans, fruits, and vegetables) enlarge the stools, easing
passage, and they speed up transit time. In this way, the undigested fibres, together with the
microbial growth they stimulate, help to alleviate or prevent constipation. Taken with ample
fluids, fibres help to prevent several GI disorders. Large, soft stools ease elimination for the
rectal muscles and reduce the pressure in the lower bowel, making it less likely that rectal
veins will swell (haemorrhoids). Fibre prevents compaction of the intestinal contents, which
could obstruct the appendix and permit bacteria to invade and infect it (appendicitis).

FOOD SOURCES OF CARBOHYDRATES.

 Cereals – These include Maize, Wheat, Rice, Millet and all their products
 Legumes – Beans, Peas, Green grams, Groundnuts
 Roots & Tubers – Potatoes, Yams, Bananas, Cassava, Arrow roots
 Fruits and Vegetables – All types of fruits and vegetables and also cane sugar
Macronutrients: Proteins

is the most abundant component in the body next to water. It accounts for about a sixth of the
live body weight and a third of it is found in the muscles, a fifth in the bones and cartilages, a
tenth in the skin and the remaining in other tissues and body fluids.
Protein refers to a very large group of hydrocarbons thus are complex compounds. They are
present in all living tissues both plants and animals. They contain nitrogen in addition to
carbon, oxygen and hydrogen a feature that distinguishes it from carbohydrates and fats.
Some proteins contain sulphur and sometimes phosphorous, iron and cobalt.
Protein synthesis; Plants are the primary sources of proteins in nature, they are synthesized by
plants from nitrates and ammonia in the soil. Herbivorous animals use plants proteins to meet
their proteins needs. Man uses plant foods and also animal foods to meet his protein needs.
Nitrogen is returned to the soil through degradation of products of animal metabolism,
excretion of nitrogen compounds in urine and feaces and decomposition of animal bodies at
death to complete the natural nitrogen cycle.
Proteins are built from basic units called amino acids which combine to form proteins by
means of peptide bonds which join the carboxylic carbon of one amino acid with the
nitrogen of the amino group of another. The resulting peptide has a free carboxyl at one end
and a free amino group at the other end permitting addition of other amino acids at either
ends. Proteins are thus amphoteric i.e. it has one end that is basic and the other that is acidic.

Fig. 1; The structure of an amino acid; Adopted from Betts et al., 2017. Human Anatomy
and physiology Text Book.
 Types of amino acids;
There are 20 common amino acids, 9 of which are essential and 11 are non-essential.
i. 1. Essential amino acids; are amino acids that cannot be made in the body. They must be
supplied through the diet. They are also known as indispensable amino acids. E.g.
 Histidine
 Isoleucine
 Leucine
 Lysine
 Methionine
 Phenylalanine
 Threonine
 Tryptophan
 Valine.
ii. Non-essential amino acids;
These are amino acids that must not be supplied through the diet because the cells of the body
can make them as needed from nitrogen and other precursors available through the process of
transamination which is the process of removing the amino of one amino acid and combining
it with carbon from a molecule of glucose to create a different particular amino acid. This
process takes place in the liver.
They are also known as dispensable amino acids. E.g.
 Alanine
 Arginine
 Asparagine
 Aspartic acid
 Cystine/cysteine
 Glutamic acid
 Glutamate
 Glycine
 Proline
 Serine
  Tyrosine
N/B the terms essential and non-essential refer to whether they must be supplied through the
diet, not to their relative importance. All 20 amino acids must be available for the body to
make proteins.
The amino acids are joined together in unique sequence to determine the protein’s primary
structure. Most proteins contain several dozen to several hundreds of amino acids. Just as the
26 letters of the alphabet can be used to form infinite number of words so can amino acids be
joined in different amounts, proportions and sequence to form a great variety of proteins.
Amino acids may form proteins that are straight, folded or coiled along one dimension or they
may take on the shape of a sphere or a globe. A protein’s shape determines its function.
Forms of proteins;
i. Fibrous form
ii. Globular form
i. Fibrous proteins;
These are proteins that are found in structures e.g. collagen of connective tissues, myosin of
muscles and keratin of hair.
ii. Globular proteins;
These are very soluble proteins that occur in tissue fluids e.g. casein in milk, egg albumin and
globulins of blood plasma.
Types of proteins;
i. Simple proteins
ii. Conjugated proteins
iii. Derived proteins
i. i. Simple proteins;
These are proteins that yield amino acids upon hydrolysis e.g. globulins, albumin, glutenins,
prolamins and albuminoids. Albumin and globulins are soluble in water and salt solutions and
are present in animal fluids (milk and blood plasma). Those less soluble are present in tissues
e.g. muscle protein myosin.
ii. ii. Conjugated proteins;
These are combinations of simple proteins with non-protein substances. This result in products
that are very functional for the body. E.g.
  Lipoproteins found in plasma (High Density Lipoproteins, Low Density Lipoproteins
etc)
 Nucleoproteins e.g.nucleic acids found in the cell -DNA and RNA
 Mucoproteins and glycoproteins and polysaccharides found in gastric secretions e.g
mucin.
 Phosphoproteins (protein and phosphorous) such as casein found in milk
 Mettaloprotein (protein and metal) e.g. those found in ferritin
iii. Derived proteins;
These include proteoses, peptones and peptides formed in various stages of protein
metabolism.
Types of dietary proteins;
With the exception of fruits and oils, all categories of foods have proteins of varying amounts
and quality. It is the amino acid profile that determines the quality of food proteins. i.e. the
ability to support protein synthesis.
Dietary proteins can be divided into two categories based on their quality. They are;
i. Complete proteins; these are proteins which are composed of all the nine essential
amino acids needed by the body to support tissue growth and repair. They are known as
proteins of high biological value (HBV).With the exception of gelatin, all animal
sources of proteins e.g. meat, fish, poultry, eggs, milk and dairy products are complete
proteins. Soya beans are the only complete plant proteins.
ii. Incomplete proteins; these are proteins that provide all the essential amino acids but
have one or more limiting amino acids that render them incapable of meeting the
body’s need for normal protein synthesis i.e. they are proteins that are low in one or
more essential amino acid thus known as proteins of low biological value (LBV).
Apart from soya beans, all plant proteins are incomplete proteins. Limiting amino acids
differ among plant foods e.g. grains are typically low in lysine, legumes are low in
methionine and cysteine and nuts are low in lysine and isoleucine. Maize is also
lacking in tryptophan.
N/B combining two different incomplete proteins or a small amount of any complete protein
with an incomplete protein boosts the overall quality to that of a complete protein.
Proteins that can be combined to obtain sufficient quantities and proportion of all essential
amino acids are called complementary proteins. Examples of two complementary plant
proteins are beans and maize, beans and rice, peas soup and toast of bread, peanut butter
sandwich etc.
Protein Quality
The protein quality of the diet determines, in large part, how well children grow and how well
adults maintain their health. High-quality proteins provide enough of all the essential amino
acids needed to support the body’s work, and low quality proteins don’t.
There are two factors that influence protein quality:
i. The protein’s digestibility and
ii. Its amino acid composition
- Digestibility; proteins must be digested before they can provide amino acids. Protein
digestibility depends on factors such as the protein’s source and the other foods eaten with it.
The digestibility of most animal proteins is high (90 to 99 percent); plant proteins are less
digestible (70 to 90 percent for most, but more than 90 percent for soy).

-Amino Acid Composition; To make proteins, cells must have all the needed amino acids
available simultaneously. The liver can produce any nonessential amino acid that may be in
short supply so that the cells can continue linking amino acids into protein strands. If an
essential amino acid is missing, however, a cell must dismantle its own proteins to obtain it.
Therefore, to prevent protein breakdown, dietary protein must supply at least the nine essential
amino acids plus enough nitrogen-containing amino groups and energy for the synthesis of the
others. If the diet supplies too little of any essential amino acid, protein synthesis will be
limited. The body makes whole proteins only; if one amino acid is missing, the others cannot
form a “partial” protein. An essential amino acid that is available in the shortest supply relative
to the amount needed to support protein synthesis is called a limiting amino acid.

High-Quality Proteins contains all the essential amino acids in amounts adequate for human
use; it may or may not contain all the others. Generally, proteins derived from animal foods
(meat, seafood, poultry, cheese, eggs, and milk and milk products) are high quality, with an
exception of gelatin.

Low-quality Proteins are derived from plant foods (legumes, grains, nuts, seeds, and
vegetables). They tend to be limiting in one or more essential amino acids. Soy bean proteins
are the one plant proteins with high quality.

Uses of proteins;
i. Building of body structures and framework; 50% of proteins in the body are found
in skeletal muscles and approximately 15% is found in the skin and blood.
ii. They are important components of enzymes; enzymes are proteins that facilitate
specific chemical reactions in the body without undergoing changes themselves e.g.
amylases.
iii. They are required for the formation of body fluids and other body secretions; e.g.
 hormones e.g. insulin, thyroxine
 neurotransmitters e.g. serotonin and acetylcholine
 antibodies
 breast milk
 mucus
 sperms
 histamines.
iv. Regulation of fluids and electrolytes balance in the body; proteins help in
maintaining fluid and electrolyte balance because they attract water thereby creating an
osmotic potential. Circulating proteins i.e. blood proteins like albumin maintain the
proper balance of fluids among the intravascular (i.e. within the veins and arteries),
Intracellular (i.e. within cells) and interstitial (i.e. in the fluids between the cells)
compartments of the body.
v. Acid-base balance; proteins also help in maintaining acid-base balance in the body in
that amino acids are both acidic and basic (amphoteric) i.e. acid because of COOH and
base because of NH2. Amino acids can act as either base or acids depending on the pH
of the surrounding fluids i.e. they buffer or neutralize excess acids and bases thus able
to maintain normal blood pH which protects the body’s proteins from being denatured
and subsequent loss of function.
vi. Transport of molecules through the blood; proteins in the body help in the transport
of substances e.g.
  Lipoproteins helps in transport of fats, cholesterol and fat-soluble vitamins
 Haemoglobin transport of oxygen
 Albumin transport free fatty acids and many drugs.
vii. Proteins like carbohydrates provide the body with energy; i.e. 1 g of proteins yields
4 kcal of energy upon metabolism, although it is not the body’s preferred fuel. It is a
source of energy when it is consumed in excess of need or when calorie intake from
carbohydrates and fats is inadequate.
Functions of amino acids;
i. Amino acids are components of numerous body components; such
 Opsin, the light sensitive visual pigment in the retina eye and
 Thrombin a protein necessary for normal blood clotting.
ii. Amino acids in the body are used by body cells in the synthesis of other nitrogen
containing compounds e.g.
 Purine in DNA synthesis
 Glycine is a component of polyphyrin present in haemoglobin and also a constituent of bile
acids. It also combines with various toxic substances which are excreted in harmless forms.
 Glycine, methionine and arginine are are used to synthesise creatinine with which with
phosphate forms creatine phosphate an important form of high energy compound in cells.
 Methionine, the sulphur-containing amino acid is the principal donor of methyl groups in
the synthesis of choline and other important compounds.
iii. Amino acids may also be converted to other compounds used in generation of energy e.g.
glucose through the process of gluconeogenesis and fats through the process of
lipogenesis where there is inadequate dietary carbohydrates and when glycogen stores
have been depleted /exhausted
Recommended Dietary Allowance (RDA) of Proteins;
RDA of proteins for a healthy adult is 0.8g/kgbwt/day which is approximately 10% of the
recommended total kilocalories.
RDA for a “reference man” and “reference woman” is 56g and 46g respectively
Factors that cause an increase in the protein needs are;
 Inadequate calorie intake because proteins are required for energy production
 Healing of the body itself e.g. during surgery, trauma or burns. People with severe burns
 may require as much as 2.0g/kgbwt/day of proteins.
 Increased requirements for normal tissue growth during pregnancy, lactation and infancy
through adolescents. For infants at the first 6 months of life they need 1.52g/kg bwt/day
(i.e. almost double of an adult).
N/B protein restriction is used for people with severe liver disease and those with renal failure
who are unable to excrete nitrogenous wastes e.g. urea. Therefore give 0.6g/kgbwt/day
(approximately 40g/day). (RDAs are meant for healthy people only).
Food sources of proteins;

 Milk and milk products

 Cereals e.g. maize, rice, wheat
 Legumes e.g. beans, green grams, peas
 Meat and meat products e.g. beef, mutton, poultry, fish, pork etc.
 Eggs etc.
DIGESTION AND ABSORPTION
Digestion
The purposes of digestion are to hydrolyze proteins to amino acids so that they can be
absorbed and to destroy the biologic specificity of the proteins by such hydrolysis. In addition
to the foods ingested, the mixture to be digested includes a sizeable amount of protein that is
constantly being released from the worn-out cells of the mucosa and of the digestive enzymes
themselves. The endogenous and exogenous sources of the amino acids are indistinguishable
and present a mixture for absorption that differs from that provided by the diet alone.

Saliva contains no proteolytic enzyme, and thus the only action in the mouth is an increase in
the surface area of the food mass as a result of the chewing of food. Most of the hydrolysis of
protein occurs in the stomach, duodenum, and jejunum, A given enzyme is capable of splitting
only specific linkages; it does not attack each and every linkage.
 Pepsinogen produced in the stomach, is activated by hydrochloric acid to pepsin. Pepsin
brings about cleavage of the peptide chain at points where phenylalanine or tyrosine
provides an amino group. Such splitting of the chain results in shorter fragments often
referred to as proteoses.
 Trypsinogen, one of the inactive proteases produced by the pancreas, is activated to
trypsin by enterokinase, an enzyme produced in the intestinal wall. At a pH of 8 to 9,
trypsin splits peptide linkages at points where lysine or arginine provide the carboxyl
group. Chymotrypsinogen, another inactive pancreatic enzyme, is activated by
trypsin to Chymotrypsin, which attacks the peptide chain at linkages in which
phenylalanine, tyrosine, methionine provide the carboxyl group, or tryptophan. Thus, with
 cleavage at these specific points, the protein molecule will have been split into many
smaller fragments,
 Peptidases split off amino acids at the terminal linkages while carboxypeptidases split off
the amino acids next to a terminal carboxyl group, and amino peptidases attack the
linkages next .to the terminal amino group. The mucosal epithelium contains peptidases,
and dipeptide hydrolysis probably occurs at the membrane surfaces.

Effect of Protein denaturation

Proteolytic enzymes not only bring about the splitting of the peptide linkages but they also
split the cross-links that connect the peptide chains. During moderate heating of proteins some
of the cross-linkages are split, thereby facilitating digestion. On the other hand, excessive
heating results in the formation of linkages that are resistant to the digestive enzymes. As a
consequence the amino acids so linked may not be available at a rate that is necessary for
incorporation into new proteins. One resistant linkage is that of lysine with carbohydrate as a
result of high heat, usually prolonged. The brown crust of bread contains less available lysine
than does the white crumbs, toasting of bread results in small losses. If break-fast cereals are
processed at high temperatures, they are also subject to such losses. These changes may be
significant when relatively low-protein diets of poor quality are consumed.

Effect of enzyme inhibitors

Some foods such as navy beans and soybeans contain substances that inhibit activity of
enzymes such as trypsin. Consequently, the utilisation of the proteins of these foods is less
efficient. Heating inactivates these inhibitors, thereby improving the digestibility of the
protein.

ABSORPTION
Amino acids are absorbed from the proximal intestine into the portal circulation. The rates of
absorption of amino acids absorption is determined by:
The total load of amino acids released through digestion
The proportions of the various amino acids present in the mixture to be absorbed
The availability of carriers to ferry the amino acids into the mucosal cells
The uptake of amino acids by the tissues

The concentration of free amino acids in the intestinal lumen is at no time great. The liberation
of amino acids through digestion is coordinated with the rate of absorption. As a consequence,
there is a minimal loss of amino acids in the faeces. The rate of absorption also appears to be
controlled by the levels existing in the blood, Amino acids are rapidly removed from the
circulation and the concentration in the blood at any given time is relatively low.

Active transport and specific carriers

Amino acids are absorbed by active transport, but some diffusion of amino acids also occurs.
The amino acids are always in competition for the carriers, with some amino acids being
absorbed much more rapidly than others.

Unit Name: Macronutrients- Lipids

The term a lipid is used scientifically to refer to a group of compounds, both animal and plant
that have a greasy, oily, or waxy consistency. They comprise of triglycerides (fats and oils),
phospholipids and sterols. These are insoluble in water but are soluble in organic solvents
such as ether, alcohol, benzene, chloroform and acetone.

Triglycerides are the most obvious of the lipids, both in food and in the body, as they represent
95% of the total food fats while the remaining 5% comes from phospholipids (e.g. lecithin)
and sterols (e.g. cholesterol).

In many occasions, the term fat is used to refer to all lipids.

Fats are essential nutrients in the human diet due to the energy value that they contribute to the
diet. They are especially useful components in the diets that require high amounts of calories.

It is usually recommended that approximately 30% of the total calories in our daily diet should
come from fat.

Composition of Fats

Fats are composed of three elements namely; carbon, oxygen and hydrogen. They are
composed mainly of fatty acids. An acid is a substance made up of a chain of carbon atoms to
which hydrogen atoms and oxygen atoms are attached. The characteristics of flavor, texture,
melting point and nutritive value depend on the kind of fatty acids the fat contains. A food fat,
whether solid or oil contains a mixture of fatty acids as fatty acids. All fats and oils regardless
of their acids contents have the same energy value, yielding nine calories per gram, providing
more energy than carbohydrate or proteins.
Characteristic of fats (physical) and chemical properties
The various characteristics of fats are;
 Melting point
Each fat has its melting point and solidification point. Fats which contain a high proportion of
saturated fatty acids like stearic and palmitic are usually solid at room temperature. Lard is
mostly solid, but margarine can melt at a temperature of 350
 Emulsification
Fats are capable of forming emulsions with liquids. Fats and oils are lighter than water. They
are insoluble in water and form heterogeneous mixture with water and when they are in the
blood phospholipids and proteins they maintain emulsion.
 Saponification
This refers to the formation of a soap of fatty acid and a cation. In the alkaline medium of the
intestine, for example free fatty acids may combine with calcium to form an insoluble
compound that is excreted in faeces. In certain diseases characterized by poor fat absorption
e.g sprue, the loss of calcium can be significant. When fat is heated with sodium and potassium
hydroxide they readily undergo hydrolysis and become salts of fatty acids such as sodium or
potassium palmitate (soap). The hydrolysis of fats with heat and alkaline into soap formation is
known as saponification.
 Hydrogenation
An unsaturated fatty acid becomes saturated if it combines with hydrogen. The process of
hydrogenation takes place when unsaturated fats are exposed to hydrogen in high temperature
in the presence of a catalyst like nickel or cobalt. The importance of hydrogenation is that
when oil becomes solid, it can easily be transported and exported.
Vegetable oils can be hydrogenated for example margarine, Kimbo and vegetable ghee.
Groundnuts, cotton seeds and coconut oils are usually used for hydrogenation. Their melting
point is between 35 and 37 degrees centigrade. Apparently, the hydrogenation of fats has a
disadvantage in that the carotene that is usually present in the oils is lost during hydrogenation.
It also reduces the linoleic acid content. This requires fortification of vitamins especially A and
D and color to be added.
 Rancidity
The presence of air can induce oxidation of fats resulting in changes in flavor and odour. This
change is commonly known as rancidity. Water needs. This occurs readily in fats that have a
high proportion of unsaturated fatty acids.
Some fats are naturally protected from rapid oxidation by the presence of anti-oxidants like
Vitamin E.
Types of Lipids
 Triacyglycerols or Triglycerides
 Cholesterol
 Glycerolphospholipids
 Sphingolipids
 Eicosanoids
A class of lipids called triglycerides provides most of the energy dietary fat. Triglycerides
account for approximately 98% of the lipids in food and are the major storage form of fat in
the body. They are made up of two components: glycerol and fatty acids.
Role of Lipids In The Body

a. Source of essential fatty acids

(The essential fatty acids are those that the body cannot synthesize and must be supplied by
food. These are polyunsaturated linoleic and linolenic acids-captured in EFA section).
Essential fatty acids are needed for the normal functioning of all tissues, as they form a part of
the structure of the cell membrane especially the brain, helping to transport nutrients and
metabolites across the cell membrane. Linoleic is involved in the transport and metabolism of
cholesterol. Essential fatty acids are also involved in brain development (Grey matter – 50%
lipids and white matter – 70% lipids). EFA are also required for the synthesis of
prostaglandins, hormone like compounds that act as regulators. Prostaglandins are synthesized
mainly from arachidonic acid.
b. Carrier of fat soluble vitamins
Fats serve as carriers of vitamins A, D, E and K. The conditions that interfere with the
absorption or use of fat reduce the amount of fat-soluble vitamins available to the body.
c. Energy source
Fat is the body’s most concentrated energy source. Except for the cells of the brain and central
nervous system (CNS), all cells can use fatty acids directly as an energy source.
Fat supplies more energy than carbohydrate and protein.
 d. Reserve fuel supply source
Excess calories are stored in the adipose cells (group of specialized cells) whether from
protein, carbohydrate or fat. Fat that has been deposited in fat tissue cannot be excreted; fat
stores are only used when the calorie value of the food eaten is less than the body’s energy
needs, then fat is released to provide energy. Serve as reserve fuel (bank balance) that can be
drawn when necessary, e.g. in time of illness or food intake is low or restricted.
e. Insulator and protector
Fat deposits beneath the skin help insulate the body, protecting from excessive heat or cold.
Fats around the body figure pads the joints and other body parts, such as the soles, palms, and
buttocks, protecting them from outside pressure. Fat also protects the vital organs, such as the
heart and kidneys, by holding them in position and protecting them from physical trauma.
f. Provider of meal satisfaction
Fats add flavor, texture and taste to meals and help to make food palatable. Fats remain in the
stomach longer than either protein or carbohydrate because they are digested and absorbed at
lower rate. This prolonged digestion contributes to a feeling of fullness and delays the onset of
hunger pangs. Fat has a high satiety effect.
Fat reduces the total volume of food taken, because of its high satiety value and concentration
of energy.
Digestion of Fats
a. Mouth
In the mouth fats are brought to a temperature which favours digestive operations. There is no
action of fats in the mouth.
b. Stomach
The gastric lipase is only capable of hydrolyzing alimentary fats which are already emulsified
e.g. egg yolk, ice cream and salad dressings, but the action is not important. It is more
important in infants. The presence of fats in the foods delays emptying of the stomach. This
mechanism of the delay has been attributed to the inhibitory action of the stomach of a
hormone enterogastrone which is liberated when fat enters the duodenum.
c. Small intestine
As the chyme enters the duodenum the presence of fats stimulates the intestinal wall to secrete
cholecystokinin, a hormone that is carried to the gall bladder by the bloodstream. The hormone
stimulates the contraction of gall bladder thereby forcing bile into the common duct and then
into the small intestine. Bile has several important functions in fat digestion and absorption.
Functions of bile in fat digestion and absorption

● It stimulates peristalsis
● It neutralizes the acid chyme coming from the stomach pH 6-7
1. Emulsifies fats thereby increasing the surf Eastwood, M., 2013. Principles of Human
Nutrition. John Wiley & Sons
● ace area exposed to enzyme action
● Lowers surface tension so that intimate contact between the fat droplets and the enzyme is
possible
Pancreatic lipase also flows into the duodenum and then into the small intestine. The
pancreatic lipase splits triglycerides into fatty acids, diglycerides, monoglycerides and
glycerol. Pancreatic juice also contains phospholipids and cholesterol esterase, enzymes which
hydrolyze phospholipids and cholesterol respectively.
The action of intestinal lipase decomposes the lipids to glycerol, fatty acids and partial
glycerides. The end products of lipid hydrolysis that are presented for absorption include fatty
acids, glycerol, monoglycerides and probably some diglycerides and triglycerides. The
contents of the small intestine are not sufficiently alkaline to allow the fatty acids liberated to
form soaps with alkalis under normal conditions.
Speed of digestion
Fats that are liquid at room temperature are hydrolysed more rapidly than those that are solid.
Adults normally experience no difficulty in digesting fats from any source. Infants and young
children as well as some elderly persons seem to have somewhat better tolerance for the softer,
more highly emulsified fats such as those in dairy products. Properly fried foods do not
normally cause digestive difficulties.
When the frying temperature is too low, foods absorb excessive amounts of fat, thus
lengthening the time required for digestion. On the other hand if foods are fried at very high
temperatures, the resulting decomposition products maybe irritating to the intestinal mucosa.
Fat digestion can be reduced by: Increased mobility where food is moved along the tract too
rapidly for complete enzyme action, disease of the biliary tract where bile secretion is deficient
and disease of the pancreas where lipase is not secreted following surgery on the small
intestine.

ENERGY METABOLISM/ BALANCE

Definition of terms
Energy
Energy is defined as capacity to do work. It’s the power that helps the body to perform
activities and attain the best temperature.
Adenosine triphosphate (ATP)
a high energy compound involved in the transfer of energy within the cell.
Calorie
Unit by which energy is measured, the amount of heat needed to raise the temperature of 1kg
of water by 10c.its abbreviated as kcal
Metabolism
It is the set of life sustaining chemical transformations within the cells of living organisms
These enzymes catalyzed reactions allow organisms to grow, reproduce, maintain their
structures and respond to their environment s.
The word metabolism can also refer to all chemical reactions that occur in living organisms
including digestion and the transport of substances into and between different cells.
Basal metabolic rate (BMR ) or basal energy expenditure(BEE):
The amount of calories expended in a 24- hour period to fuel the involuntary activities of the
body at rest and after a 12 hour fast
Resting metabolic rate (RMR) or resting energy expenditure (REE):
the amount of calories expended in a 24-hour period to fuel the involuntary activities of the
body at rest. RMR does not adhere to the criterion of a 12-hour fast, so its slightly higher than
BEE because it includes energy spent on digesting, absorbing, and metabolizing food.
ENERGY METABOLISM
Energy metabolism refers to chemical change that result in the release of energy. The body has
the ability to transform food energy from one form to another. The chemical energy of food
can be converted to mechanical, electrical, and heat energy and other forms of chemical energy
in the body. Production of energy is a catabolic process since energy is released after
breakdown. The main source of energy is the sun which is transformed into chemical energy
for body use through foods eaten. All mans energy is derived from the plant and animal foods
he eats. Carbohydrates, proteins, and fats are energy yielding food substances.
The kcalories the body expends
Energy out the generation of heat, known as thermogenesis, can be measured to determine the
amount of energy expended. The total energy a body expends reflects three main categories of
thermogenesis.
 Energy expended for basal metabolism
 Energy expended for physical activity
 Energy expended for food consumption
A fourth category is sometimes involved:
 Energy expended for adaptation
 Energy expended for growth and repair
ENERGY BALANCE
Energy balance: The energy (kcalories) consumed from foods and beverages compared with
the energy expended through metabolic processes and physical activities.
People expend energy continuously and eat periodically to refuel. Ideally, their energy intake
cover their energy expenditures with little or no, excess. Excess energy is stored as fat, and
stored fat is used for energy between meals.
The amount of body fat a person deposits in or withdraws from storage on any given day
depends on the energy balance for that day- the amount consumed (energy in) versus the
amount expended (energy out). When a person is maintaining weight, energy in equals energy
out. When the balance shifts, weight changes. For each 3500 kcalories eaten in excess, a pound
of body fat is stored. Similarly a pound of fat is lost for each 3500 kcalories expended beyond
those consumed.
Weight gained or lost rapidly includes some fat, large amounts of fluid and some lean tissues
such as muscle proteins and bone minerals. Because water constitutes about 60% of an adults
body weight, retention or loss of water can greatly influence body weight over the long term,
the composition of weight gained or lost is normally about 75% fat and 25% lean tissues.
during starvation, losses of fat and muscles are about equal.
The guide that food intake is meeting energy needs in the body weight is as follows:
1. If calories consumed = to energy needs, there is constant weight maintenance.
2. If kcals consumed are more than energy needs, there is weight gain
3. If kcals consumed are less than energy needs, there is weight loss.
ENERGY INTAKE
Calories come from carbohydrates, proteins, fat and alcohol. The total number of calories in a
food or diet can be estimated by multiplying total grams of these nutrients by the appropriate
calories per gram – namely:
1 g carbohydrate=4 kcal
1 g fat=9 kcal
1 g protein=4 kcals
1 g alcohol= 7 kcal
When all food consumed is measured, the nutrient values available in food composition
references represent average, not actual nutrition content based on analysis of a number of
food samples.
The main source of energy for all body activities is food, along with energy stores in the body
tissues as reserve.
Our bodies needs fuel to carry out its work on a continual basis. This need starts at birth and
continues as long as one lives.
Energy is the primary need of the body and takes precedence over all other needs. The
metabolic products formed by digestion of carbohydrates and fats, which are simple sugars,
glycerol and fatty acids, provide most of the energy needs of the body. Energy production can
be summarized as:
Glucose, fatty acids, glycerol or amino acids + oxygen = energy + carbon dioxide + water
The actual process involves a series of complex reactions, which lead to the common pathway
known as Krebs cycle, its end products being energy, carbon dioxide and water. The energy
released is trapped in energy-rich compounds (ATP), from which it is released as required.
ENERGY EXPEDITURE
The body uses energy for involuntary activities and purposeful physical activity (PA) .the total
expenditures represent the number of calories a person uses in a day.
BASAL METABOLISM
 Basal metabolism is the amount of calories required to fuel the involuntary activities of the
body at rest after a 12-hour fast. These activities include: maintaining the body
temperature, and muscle tone, producing and releasing secretions, propelling the
gastrointestinal (GI) tract, inflating the lungs and beating the heart, the bone marrow
making new red blood cells, the heart beating 100,000 times a day, and the kidneys
filtering waste- they support all the basic processes of life.
For most people, the basal metabolic rate (BMR) or basal energy expenditure (BEE) accounts
for approximately 60% - 70% of total calories expended.
About two thirds of the energy the average person expends in a day supports the body’s
basal metabolic rate.
Energy for Physical Activity
Physical activity is that activity, which we choose to do, so it is also known as voluntary
activity. It includes;
1. The work related to one’s occupation, profession or job
2. Activities related to personal necessities, such as bathing, brushing teeth, dressing,
eating, washing clothes and utensils, commuting to work, market, etc.
3. Leisure activities such as reading, watching television, playing games (badminton,
tennis), gardening, playing with children, and walking.
The energy spent in these activities is in addition to that used for basal metabolism. The
additional energy output due to voluntary physical activity varies from as little as 10 per cent
for bedridden patient to as high as 50 per cent for an athlete
Mental work or study does not need extra energy. Similarly, anxiety or any other
emotional state does not increase energy needs, but any agitated movements, muscle
tension or restlessness may require extra energy.
Thermic effect of food
When a person eats, the GT tract muscles speed up their rhythmic contractions, the cells that
manufacture and secret digestive juices become active, and some nutrients require energy to be
absorbed. This acceleration of activity requires energy and produces heat; it is known as the
thermic effect of (TEF).
The thermic effect of food is proportional to the food energy taken in and is usually estimated
at 10 percent of energy intake. Thus a person who ingests 2000 kcals probably expends 200
kcals on the thermic effect of food. The proportions vary for different foods and are also
influenced by factors such as meal size, and frequency. in general, the thermic effect of food is
greater for high protein foods than for high-fat foods.
Adaptive thermogenesis
Additional energy is expended when circumstances in the body are dramatically changed. A
body challenged to physical conditioning, extreme cold, overfeeding, starvation, trauma, or
other types of stress must adapt. This body has extra work to do and uses extra energy to build
the tissues and produce the enzymes and hormones necessary to cope with the demand.
Because this component of energy expenditure is so variable and specific to individuals, it is
not included when calculating energy requirements.
Energy for Growth and Repair
Extra energy is needed during periods of rapid growth for the building of new tissues. These
stages of life include pregnancy, early childhood and adolescence. The total energy need of
one pregnancy is estimated to be about 4000 kilocalories. In the lactation stage, the secretion
of milk for the infant increases the mothers need for energy, the additional need is in the range
of 700 to 1000 kilocalories per day. Infants have the highest growth rate in the entire lifecycle,
and have been observed to store 2 to 15 per cent of their total energy intake. Adolescents
growth spurts results in extra need for energy; it may be as high as 25 to 30 per cent more than
adult needs.
Persons recovering from wasting diseases, from burns, blood and loss, need additional energy
for replacing the tissue damaged or lost with new tissues.
MEASUREMENT OF ENERGY
The energy value of a food is expressed in terms of a unit of heat or kilocalories which is
(abbreviated as kcal). Kilocalories is defined as the amount of heat required to raise the
temperature of 1kg (1litre) of water by one degree Celsius
FORMS OF ENERGY
The human body uses energy in many forms namely
1. Chemical
2. Thermal
3. potential
4. osmotic
5. Electrical
Food supplies the energy the energy we need for everything we do. Two components of food,
carbohydrates and fats, supply 5 to 92 per cent of the total energy in human diet. The rest is
provided by proteins.
ENERGY VALUE OF VARIOUS FOODS
1. Energy values of different foods refer to the edible portion of the food. Thus the energy
content of a food is related to the food composition.
2. Energy value of food is affected by water or moisture content of the food water does not
provide any energy. Therefore foods which have a large percentage of water, have low
calorie content.
3. Energy content varies with the foods fat content. As we learned earlier, fat provides 9 kcals
per gram, therefore foods with high fat content have a high energy value.
4. Energy value is also affected by preparation or processing.as rice absorbs water, while
cooking, cooked rice has about one-third the number of calories as an equal weight of raw
rice the reverse is the case when foods are dried. Dried fruits are concentrated source of
energy as compared to fresh fruits. Seasoning with oil increases the energy content of
salads and vegetables. Frying foods also increases their energy content.
Thus any change in the composition during processing or preparation affects the caloric
content of the food product.
Measurement of basal metabolic rate (BMR)
The BMR is normally measured early in the morning, after the subject awakens and in a
post absorptive state (10 to 12 hours after the last meal).
A number of tests are used in clinical practice currently. These tests measure the activity of the
thyroid gland. There are several ways of measuring the activity of thyroid gland, Which
produce the hormone thyroxine. The blood levels of thyroxine, the hormone which controls the
BMR, can be measured. Iodine is used in the synthesis of thyroid hormone.
Basal energy can be estimated using a general formula 1 kcals/kg body weight per hour for
men and 0.9 kcals body weight per hour for women.
The harris-benedict equations are also used to estimate the basal or resting energy needs of
hospitalized patients.
Female: 655+(9.6*wt)+(1.85*ht)-(4.68*age)
Male : 66.5+(13.75*wt)+(5.0*ht)-(6.8*age)
Where W =weight in kilograms (kg), H =height in centimeters (cm) and A = age in years.
Factors affecting the BMR:
1. Body size and composition
The heat loss from the body is related to body size; energy needed to maintain lean muscle
mass at rest is related to body composition. Original work on energy measurement was based
on body surface area. Recent studies have demonstrated that the metabolic rate is primarily
dependent on lean body mass (LBM). LBM can be accurately determined by underwater
weighing .
Athletes, who have developed muscle due to exercise, have 5% increase in BMR compared to
non-athletes. Women have 5 to 10 % lower metabolic rate as compared to men of the same
weight and height, because they have more fat and less muscles in their body than men do.
2. Age - There is a decrease in metabolic in metabolic energy expenditure of 2% to 3%
per decade after early adulthood, due to the shift in the proportion of muscle to fat in
the body. The basal metabolic rate gradually decreases after reaching adulthood; the
decrease is about 30% between 30 to 75 years.
3. Growth and Repair- the metabolic rate is highest in the stages of rapid growth, namely
the first and second years of life. There is a lesser peak in metabolic rate in the years of
 puberty and adolescence in both sexes. Infants may store 12% to 15% of their energy
intake in the form of new tissues . the metabolic rate increases in pregnancy due to growth
of the foetus and related increased growth activity.
4. Sleep
The metabolic rate falls by about 10% while sleeping as compared to the resting rate when
awake. This is due to relaxation of the muscles and reduced activity of the nervous system
during sleep.
5. State of Health
The metabolism is decreased due to malnutrition. The decrease in basal metabolism is
proportional to the degree of malnutrition. It is mainly due to decrease in the amount of
active tissue and a decrease in metabolic rate.
When one suffers from fever, the increase in temperature of the body increases
metabolism. The increase is about 7% per each degree fahrenheight above normal (98.60 F
or 37%C).
6. Hormonal Control
A hormone known as thyroxine, controls the speed of our involuntary activity. The thyroid
gland, situated in the neck, synthesizes this hormone. If two much thyroxine is released,
the rate of energy expenditure is increased. If too little is released, the energy expenditure
is reduced. The basal metabolism may decrease by 30 to 40%when the synthesis of
thyroxine is inadequate. On the other hand, the BMR may almost double due to
hyperactive thyroid gland. These conditions need prompt medical treatment.
Luckily for most of us such abnormalities are not very common. Most of us have a
normally functioning thyroid gland and hence a normal basal metabolic rate.
7. Climate
Extreme environmental temperatures affect the metabolic energy needs. The metabolic rate
of persons in the tropics is 5 to 20% higher than those in temperate regions. In hot climate,
the metabolic rate increases by about 50% due to increased activity of sweat glands. The
increase in metabolic rate due to cold depends on the body fat insulation and use of warm
clothes.
WATER

Water; is one of the most essential nutrients second to oxygen without it most of us would die
from the effects of dehydration in less than one week. We would survive for weeks or even
years without some of the essential minerals and vitamins but not without water. Technically a
loss of 20% of body water results in death, thus its greatest contribution. Most people seldom
think about the importance of an adequate intake of water and fluids.
Adults require about 6-10 glasses of water/day depending on the level of activity and the
environment. Water is the major component of our bodies i.e. 55-70% of our bodies is water.
This % tends to decrease with increase in age. Water occupies within and between cells in the
body.
Infants and children have much higher content of water than adults. Fat people have less water
than lean people.
Forms of water in the body;
Water in the body or food is present in four forms namely;
i. Bound water; this is water in food and body tissues that is attached to colloids
ii. Exogenous water; this is water from dietary sources either as liquid or as a food
component
iii. Free water; this is the portion of water in the body or food that is not closely bound by
attachment to colloids.
iv. Endogenous water; from metabolism of food in the body also know as metabolic
water of combustion.
Metabolic water;
Oxidation of all food stuffs yields water e.g.
Glucose C6H12O6 CO2 + H2O + Energy
Metabolism of 100g of foodstuffs would yield
i. Carbohydrates-55g water
ii. Proteins-41g water
iii.Fats-107g water
On average, the water produced by the body’s metabolic activity aggregates to 200-300ml/day.
Body water distribution/compartments of water;
A man’s body is about 55%-70% while a woman’s body is about 50-55% water. The higher
water proportion is due to the greater muscle mass in man.
Water holds very many body components in solution or suspension which is referred to as
fluids. Fluids found inside the cells are called intracellular fluids and it forms 55% of water
in the body and approximately 40%-45% of the body weight.
The rest of the fluids are found between the cells called extracellular fluids examples of
extracellular fluids are blood, lymph and interstitial fluids (between cells and tissues). These
fluids accounts for about 20% of the body weight.
Functions of water in the body;
i. Water acts as a building material of each cell in the body. I.e. it provides shape and
structure to cells.
ii. It is a universal solvent thus provide a necessary chemical solvent on which a variety
of body tissue solutions are based e.g. during digestion and absorption where it helps
dissolve products in the tissue fluid circulation which helps to supply nutrients and
oxygen to cells and large multitude of cell chemical reactions that fulfil the body’s
needs e.g. breakdown of sugars during metabolism which needs presence of water
because it allows oxygen to dissolve in blood and in the synthesis of hormones and
enzymes.
iii. It helps in removal of wastes from the body e.g. CO 2 from the lungs, waste nitrogenous
materials and salts through the kidneys which forms 92% of urine and faeces.
iv. It acts as a lubricant to prevent friction of many parts of the body e.g. it is a component
of mucus that line hollow structures in the body, synovial fluids in joints and it
cushions contact between internal organs that slide over one another.
v. Regulation of body temperature through its loss via evaporation from the skin and the
lungs. This helps to remove excess body heat to a comfortable level.

Water Balance;
The body normally maintains a water balance (equillibrium) i.e. amount of water ingested
equal to water excreted or lost from the body. The water balance is maintained even though
the fluid intake may vary from day to day. It is believed that the hypothalamus regulates the
intake. Water excretion is controlled by hormones antiduretic hormone and aldosteron.

Sources of water;
i. The main source of water to the body is drinking water.
ii. It is also through intake of all beverages and liquid foods that contain water e.g. fruits
and fruit juices, milk and non-caffeinated soft drinks, tea, coffee, soups, broths etc.
iii. Metabolic reactions in the body.
N/B out of 2200ml water available in the body, 1,100ml is drinking water, 900ml is from the
diet and 200ml is from metabolic oxidation.
Recommended Dietary Allowance of water;
About 1ml of water is needed per kcal energy intake. Thus is about 2000ml water is needed
when intake is 2000kcals.
Infants require about 1.5ml/kcals energy intake because of large surface area in proportion to
weight.
Factors that determine water needs;
i. Environmental temperatures
ii. Humidity
iii. Occupation
iv. Diet
N/B; apart from water obtained from food, an individual may need to drink 1.5-2litres of water
per day.
An athlete or an individual engaged in strenuous activity needs replacement of water and
electrolytes i.e. sodium and potassium.
Problems associated with water;
i. Dehydration; where the intake is less than body’s needs. It is a serious medical
problem and needs prompt attention and remedial action. It results due to diarrhea and
vomiting. Infants who have high water requirements get dehydrated very quickly when
they suffer from diarrhea.
ii. Oedema; this is the accumulation of excess fluids in tissues due to sodium content in
the extracellular tissues as a result of the inability of the kidney to excrete sodium.
Water is retained with sodium resulting in oedema. In pronounced protein deficiency,
the tissues are unable to ensure water balance and the oedema that follows is nutritional
oedema. Oedema also results from kidney diseases, cirrhosis of the liver and heart
diseases. It manifests itself through swollen feet and arms & eyelids and the
chest/abdominal cavity a condition known as ascites.