LESSON 1: MACRONUTRIENTS

MACRONUTRIENTS
 
- Provide the major source of energy for people and approximately half of the calories
which people need every day.
- Are mainly found in foods of plant origin.
 
A. CARBOHYDRATES

➢ Chemical Structure:
- Carbohydrates contain carbon, hydrogen, and oxygen (CHO). The ratio of    hydrogen
to oxygen is 2:1 as in a water molecule
 
➢ Classification:
- According to complexity of the molecules and the number of sugar units in its
chemical nature.
 
1.Monosaccharides ( one sugar unit)
2. Disaccharides (hydrolyzed into two sugar units)
3. Oligosaccharides (polymers of 3 to 10 sugar units)
4. Polysaccharides (can yield as high as 10,000 units)
 
- According to digestibility
1. Digestible: (sugars, starches, dextrin and glycogen)
2. Partially digestible: ( galactogens, mannosans, inulin and pentosans)
3. Indigestible: (cellulose and hemicellulose)
 
                      MONOSACCHARIDES:
COMMON SUGARS
Fructose (fruit sugar)  ✲The sweetest of all sugars. It occurs naturally in fruits and
honey. It is commonly added to foods, in the form of high
fructose corn syrup (HFCS).
 ✲It is hydrolyzed from sucrose and insulin. It is also called
“levulose”
Glucose (Dextrose)  ✲Also known as Dextrose/grape sugar. Found in the blood, so
it’s often called blood sugar.
 ✲Glucose is the main source form of carbohydrate that cells
use to produce energy. Glucose is present in some foods such
as fruits, vegetables, corn syrup, and honey.
 ✲All other sugars are converted into glucose and it is oxidized
in the cells to release energy.
Galactose  ✲is not found free in nature but is hydrolyzed from lactose or
milk sugar.
  ✲Is a component of some compound lipids called the
cerebrosides which are found in the brain and nerve tissues.
SUGAR ALCOHOLS  ✲both have the same sweetening power as glucose.
(C6H12O6) (mannitol  ✲Sorbitol has been used to delay the onset of hunger.
and sorbitol)  ✲Mannitol is poorly absorbed in the intestines and is used
more as a food ingredient as drying agent.
PENTOSES (ribose and  ✲are five-carbon chains of simple sugars or monosaccharides
ribulose) that are found in nucleic acids of meat and sea foods in bound
form.
 ✲in the body, they are important components of nucleic acid
and some co-enzymes.
 Others  ✲When you look at ingredients on a food label, you’ll find all
kinds of terms referring to sugars. A food is likely to be high in
sugars if one of these names appears first or second on the
ingredient list 
 
   
                         DISACCHARIDES:
Sucrose “table sugar.”  ✲Sucrose comes from plants such as beets, sugar cane, and
  corn.
 ✲is sometimes called cane sugar or beet sugar since it is
commercially prepared from sugarcane and sugar beets.
 ✲It is also abundant in molasses, maple syrup, sorghum and
some fruits.
 ✲Is the most common form of sugar in cooking and in table
service, hence is called “table sugar.”
MALTOSE “Malt Sugar”  ✲is also called malt sugar because it is derived from the
digestion of starch with the aid of the enzyme, diastase, found
in sprouting grains.
 ✲In the intestines, maltose is not readily fermented by
bacteria and this is beneficial for infant feeding.
 ✲Usually this is combined with dextrin (dextrimaltose) for
infant milk formula.
Lactose “milk sugar"  ✲The main sugar in milk. Some people have trouble digesting
Lactose, which is known as lactose intolerance. 
 ✲It is hydrolyzed to glucose and galactose and is slowly
digested compared to the other disaccharides.
 ✲It is the least sweet among common sugars, only 1/6 as
sweet as sucrose or table sugar.
 
 
POLYSACCHARIDES - they are not water- soluble compared to mono and
disaccharides.
STARCH  ✲is the world’s most abundant and cheap form of
carbohydrates.
 ✲It is the storage form of carbohydrates in plants: in grains,
seeds, tubers, roots, and unripe fruits.
DEXTRIN  ✲is an intermediate product of starch digestion or is formed
from partial hydrolysis of starch.
 ✲The action of dry heat on starch (as in toasting bread or
browning of cake crust in the oven) produces dextrin.
GLYCOGEN “animal  ✲is sometimes called animal starch because it is the storage
starch” form of carbohydrate in the body, chiefly in the liver and
muscles.
 
DIETARY FIBER
- provides bulk, acts a broom in our digestive tract to prevent constipation and recently
has been shown to prevent diverticular diseases, reduce incidence of colon cancer,
reduce blood cholesterol level and decrease mucosal absorption.
 
FIBER
-  also called roughage, is the indigestible part of food. The most well known dietary
fiber is cellulose.
 
CELLULOSE
- is a polysaccharide composed of many glucose units in a straight chain like starch.
 
HEMICELLULOSE
- is also an indigestible polysaccharide found in agar, pectins, woody fibers, leaves and
stems, but is less polymerized than cellulose and can be hydrolyzed by dilute acids. It is
composed of other sugars besides glucose (has pentoses, galactose, and acid forms of
these sugars.)
 
ECTIN AND AGAR-AGAR
- are soluble fibers, their importance in food is as thickening or binding agents and to
form food gels.
- In the colon, they form bulk by absorbing large amounts of liquid and swelling into a
colloidal mass which exerts a laxative effect.
 
PSYLLIUM
- is a soluble fiber obtained from a seed of a plant known as genus plantago ovata. It is
composed of 80% dietary fiber and small amounts of protein, fat, vitamins and
minerals.
 
 
Function of Carbohydrates
1. Chief source of energy - body cells require a steady and constant supply of energy
mainly as glucose and its intermediate products.
 
✓ Factors that lower blood sugar level – the dietary and metabolic factors are:
prolonged undernutrition, increased exercise, poor absorption of glucose, liver damage,
kidney malfunction, and hormonal deficiencies like adrenal insufficiency, insulin
increase, hypothyroidism and anterior pituitary deficiency.
 
✓ Factors that increase blood sugar level – these include excessive carbohydrate
intake, reduced exercise, increased glucose absorption, some liver disorders, toxemias,
diabetes mellitus, increase pituitary and hyperactive adrenal cortex hormones, fright
and anger.
✓ Factors that maintain blood sugar level – they are reversible glycogen-glucose
reaction in the liver, conversion of carbohydrate to fat, excretion of glucose, formation
of glycogen in the muscle and glycogen utilization, and utilization of carbohydrate by
other tissues.
 
2. Cheap and main energy food - carbohydrate foods mainly as cereal grains,
sugars, most fruits and starchy vegetables contribute at least half or 50% of total
energy needs of people. They are low-cost and widely distributed around the world.
 
3. Protein sparer – the energy need of the body is given first priority over body-
building needs. Thus, if carbohydrate foods are not adequately supplied, protein will be
catabolized to provide heat and energy instead of being used for building and repairing
tissues.
 
4. Regulator of fat metabolism – carbohydrates prevent incomplete oxidation of fat.
 
5. Sole energy source for the brain and nerve tissues – the brain and nerve
tissues utilize only glucose for energy. A constant supply of glucose must reach these
important tissues. Otherwise, lack of glucose or oxygen needed for the oxidation of
glucose to release energy will result in an irreversible damage to the brain.
 
6. Storage form of energy as glycogen – unlike fat storage in adipose tissues,
glycogen provides immediate source of energy.
 
7. Regulator of intestinal peristalsis and provider of bulk – commonly called
fiber or roughage in the diet, cellulose, and indigestible polysaccharide acts as a broom
and regulates intestinal peristalsis.
 
➢ Sources of Carbohydrates
The most common food sources of carbohydrates are, sugars, cereal grains and their
products (rice, corn, oat, breads and other baked goods, noodles or pasta,etc.); root
crops, starchy vegetables and dried legumes. Fruits and milk also contribute good
amounts of carbohydrates.
 
➢ Carbohydrate Malnutrition
In severe deficiencies, as in the case of famine and prolonged starvation, the ill effects
of a limited total food intake result in multiple nutrient deficiencies, particularly, PEM
( Protein Energy Malnutrition).
 
Clinical signs: decreased blood sugar level, weight loss, and retarded growth for
infants and children.
➢ In excessive intake of calories, whether from carbohydrates,  fats, or proteins,
obesity or adiposity becomes the problem.
➢ If the intake of fat and protein is normal, but the carbohydrates intake is lower than
the recommended level to supply caloric requirements, ketosis or acidosis occurs.

B. PROTEIN AND AMINO ACIDS

 
Protein
- originated from from a Greek word proteios meaning “to hold first place” or “is of
prime importance.”
 
Chemical Structure
- Proteins are large complex organic compounds composed of amino acids as the
building units linked together in peptide bonds.
 
Amino Acids
- building blocks of proteins, there are 22 amino acids and each is distinguished by the
characteristics radical(R) attached to the alpha carbon.
Elements of proteins are: carbon, hydrogen, oxygen and nitrogen (CHON).
 
CLASSIFICATION OF AMINO ACIDS:
 
1. According to essentiality 
– an essential amino acid (or indispensable amino acid) is one that cannot be
synthesized by the body from materials readily available, at a speed to keep up with
normal growth rate. Essential amino acids are referred to as dietary essentials.
- There are 8 essential amino acids for an adult and 10 for a growing child. Histidine,
isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine
 
Note:
* Arginine - required fro young adult but not in adult
* Histidine - Indispensable during infancy making it conditional amino acid and re-
classified as an essential amino acid through out human lifespan
 
Semi-essential (or semi-indispensable) amino acids
- reduces the need for particular essential amino acid (EAA) or partially spares it. This is
an amino acid that can maintain life processes for an adult but not enough for normal
growth in children. Example is arginine.
- arginine, tyrosine, cystine, glycine, serine
 
Non-essential amino acid (NEAA) 
– it is also called “dispensable amino acid” because it is not a dietary essential. Ex.
Glutamic acid, aspartic acid, alanine, proline, norleucine, citrulline, hydroxyglycine,
hydroxyproline
 
2. According to the chemical composition of their side chains.
a) Basic Amino Acids – those with additional amino acid group. Examples are lysine,
arginine, histidine.
b) Acidic Amino Acids – those that contain additional carboxyl group. Examples are
aspartic acid, glutamic acid.
c) Neutral Amino Acid – those that contain additional acidic or basic group classified into
aliphatic and aromatic or cyclic amino acids.
-  Aliphatic AAs – threonine, glycine, serine, alanine
-  Aromatic or cyclic AAs – tryptophan, phenylalanine, tyrosine
 
3. According to hydrolytic products and sources
Glucogenic – they follow carbohydrate pathways in metabolism
Ketogenic – they are converted to ketone bodies like acetate; acidic, basic or neutral
(depending on pH reactions).

4.     According to structure and spatial arrangement of amino acids.

 
 
FUNCTIONS OF PROTEINS AND AMINO ACIDS
 
GENERAL FUNCTIONS:
1)  Build and repair cells and tissues (structural role)
2)  Supply energy ( a fuel nutrient)
3)  Regulate body processes (regulator of physiologic processes) – protein regulates
osmotic pressure; hence helps maintain water balance and acid-base balance.
 
Specific roles of an Amino Acid:
Methionine – is a methylating agent and helps form the heme of red blood cell and
choline.
Phenylalanine – is the precursor for tyrosine. Both are important in the production of
2 hormones: thyroxine and epinephrine.
Tryptophan – is a precursor for niacin, a B-vitamin
 
Note:
➢ Thyroxine- hormone that are primarily responsible for metabolism (produced by the
thyroid gland)
➢ Epinephrine – (known as adrenaline) hormone produced by the adrenal gland.
FXN: neurotransmitter (fight or flight response)
➢ Niacin – Also called nicotinic acid an organic compound and a formed of vit B3, tx
High blood cholesterol, pellagra (niacin insufficiency)
 
Glycine – combines with toxic substances to render them harmless.
 
Leucine, Isoleucine, and Valine – all enter the alanine-glucose cycle to release the
nitrogen to other intermediate metabolites that need it.
 
 
WAYS OF IMPROVING PROTEIN QUALITY:
• Fortification – refers to the addition of amino acids in desirable levels so that food
contains more than what originally exists. (i.e. lysine added to bread)
 
• Enrichment – to restore what was lost during the milling process by adding an
amino acid according to Food and Drug standards (i.e. lysine to Cerelac)
 
• Supplementation – refers to the addition of protein rich foods to regular diet so as
to increase total protein content and improve its standards (i.e. high protein milk given
in addition to lugao or fruits or vegetables
 
• Complementation – refers to the combination of food proteins such that one
lacking in an essential amino acid is provided by another rich in that amino acid.
Examples are: rice and munggo, soybean and wheat, soybean and nuts, soybean and
corn, soybean and red kidney bean.
 
How to determine the average adult’s daily protein requirement:
Weight in kg x 0.8 (gram of protein per kilogram of body weight).
 
Fibrous proteins – they are found in the protective tissues of animals such as skin,
hair, tendons, feathers, and the fins and scales of fish. These are insoluble in water and
are able to provide support for cells and tissues.
Examples:
Keratin – chief protein in hair
Collagen – connective tissue, in tendons and bone matrices
Fibrin – of a blood clot
Myosin – of muscle
Elastin – in blood vessel walls
 
Globular proteins – soluble in water. Examples are: casein in milk, cheese, albumin in
egg whites and milk, and globulin in red blood cells.
 
AMINO ACID CONTENT OF PROTEINS
1. Complete proteins – are proteins containing all the essential amino acids in amounts
sufficient for growth and maintenance of life. In general, animal proteins are complete
proteins and have high biological value. Examples are casein of milk and albumin in egg
white.
2. Partially complete proteins – are proteins that can maintain life but do not support
growth; e.g., gliadin in wheat, legumin in legumes.
3. Incomplete proteins – are proteins that cannot support life and growth; e.g., zein in
corn, gelatin and most plant proteins.
 
PROTEIN MALNUTRITION:
 
Deficiency signs:
• Early signs-general weakness, weight loss, reduced resistance to infections, lethargy
or malaise, and pallor.
• Later signs-edema and dry scaly skin. In children, growth is retarded and liver is
enlarged.
 
Prolonged malnutrition of protein, as well as calories, results in the deficiency disease
known as PEM (Protein-Energy Malnutrition) or CPM (Calorie-Protein malnutrition).
 
FORMS:
Marasmus
- condition resulting from severe malnutrition which usually afflicts very young children
who lack both energy and protein foods as well as vitamins and minerals.
- Physical symptoms/manifestations:
   • Emaciated but does not have edema
   • Hair is dull and dry
   • Skin is thin and wrinkled

Kwashiorkor
-appears when there is a sudden or recent lack of protein containing food (such as
during a famine).
- Usually affects children as well as adults
- This disease causes fat to accumulate in the liver and the lack of protein and 
hormones result in EDEMA, painful skin lesions, and changes in the pigmentation of the
skin and hair.
- Mortality rate for this case or condition is high than marasmus.
 
DIFFERENTIATING MARASMUS FROM KWASHIORKOR
MARASMUS KWASHIORKOR
Total surface fat and midarm TSF and MAC within normal limits
circumference decreased  
Weight decreased Weight possibly within normal limits
Visceral proteins (albumin) within normal Visceral proteins decreased
limits or decreased  
Immune function within normal limits Immune function decreased
Dull, dry hair Reddish – color hair
Emaciated, wrinkled appearance Puffy appearance
Lack of protein and total energy Edema

C . FATS AND OTHER LIPIDS

➢ to the cook or chef, “fat” refers to the visible fats and oils or the animal fat in a meat
carcass.
➢ to a weight conscious person, it is unwanted or an undesirable constituent of the     
body.
➢ to the nutritionist and biochemist, fats and lipids in the right kind and amount, are
necessary as components of tissues and to regulate certain life processes.
 
 
TERMINOLOGIES
 
• Fatty Acids
−   the physical and chemical properties of various fats and oils are due to their fatty
acids components. The most abundant fatty acids in animal fat are palmitic, stearic and
oleic acids.
−   are organic compounds of carbon atoms to which hydrogen atoms are attached.
 
 
• Hydrogenated Fats
- are polyunsaturated vegetable oils to which hydrogen has been added commercially 
to make them solid at room temperature.
- The process called hydrogenation, turns polyunsaturated vegetable oils into saturated
fats. (Example Margarine).
 
• True Fats
-   belong to a larger group of organic compounds chemically called lipids which are
insoluble in water, but soluble in fat solvents like chloroform, ether, benzene, etc. and
are utilized by living organisms.
 
They are classified into two ways:
 
1) ESSENTIAL FATTY ACIDS (EFAs) – are necessary fats that humans cannot
synthesize
➢ must be obtained in the diet
➢ are long chain polyunsaturated fatty acids derived from linoleic, linolenic and oleic
acids.
➢ consist of two families ( Omega – 3 and Omega – 6)
 
2) NONESSENTIAL – are Omega – 9 fatty acids because the body can manufacture a
modest amount provided EFAs are present.
 
Chemical Structure:
− Carbon, hydrogen, and oxygen, in glyceride linkage. The proportion of oxygen in fats
is smaller than in carbohydrates.
− In food, fats stay solid at room temperature and oils are liquid at room temperature.
 
CLASSIFICATION OF LIPIDS
1) According to the complexity of the molecule and chemical composition (simple,
compound or derived.) Fats and oils are simple lipids; they are mixed triglycerides.
2) From standpoint of physical appearance:
• Visible fats
− are purchased and used as fats such as butter, margarine, lard, and cooking oils
• Invisible fats(egg yolk, milk, olives, avocado, well-marbled lean meats)
− are those found in other foods such as meats, cream, whole milk, cheese, egg yolk,
fried foods, pastries, avocados and nuts.
 
 CLASSIFICATION OF FATS:
1. Simple Lipid (Neutral Fats)
 
Triglycerides  – are composed of three fatty acids attached to a framework of
glycerol, thus their name.
 
Note: Most lipids in the body (95%) are triglycerides. They are in body cells and they
circulate in the blood.
 
2. Compound Lipids
-are various combinations of fat with other components.

THREE TYPES OF COMPOUND LIPIDS

 
1. PHOSPHOLIPIDS -are compounds of fatty acids, phosphoric acids, and
nitrogenous bases                        a. Lecithins- are the most widely distributed of the
phospholipids
 - traces are placed in liver and egg yolk and in raw vegetable oils such as corn oil.
They are added to food products such    as cheese, margarine, and confections to aid
emulsification.
b. Cephalins- are needed to form thromboplastin for the blood clotting process.
c. Sphingomyelins- are found in the brain and other nerve tissues as component of
myelin sheath.
 
2. GLYCOLIPIDS - are compounds of fatty acids combined with carbohydrates and
nitrogenous bases            a. Cerebrosides - components of nerve tissue and certain cell
membranes where they play a vital role in fat transport.
-  their carbohydrate component is Galactose
b. Gangliosides- are made of certain glucose, galactose, and a complex compound
containing a amino sugar.
 
3. LIPOPROTEINS - are lipids combined with proteins. They are formed primarily in
the liver and  are found in cell and organelle membranes, mitochondria, and lysosomes.
− Fats are insoluble in water, which is the main component of blood. Therefore, special
carriers must be provided for the fats to be absorbed and transported by the blood to
the body cells.
− Absorption:
1) In the initial stages of absorption, bile joins with the products of fat digestion to
carry fat.
2) Later, protein combines with the final products of fat digestion to form special
carriers called lipoproteins
3) The Lipoproteins subsequently carry the fats to the body cells by way of the blood.
 
3. Derived Fats
- are simple derivatives from fat digestion or other more complex products
 
1. FATTY ACIDS - are the key refined fuel forms of fat that the cell burns for energy.
 
SOURCES OF FATTY ACIDS
A. Saturated fatty Acid - No hydrogen can be  added and it is derived from both
animal fats and plant oils
 
FOOD HIGH IN SATURATED FATS
Animal Sources Plant Sources
Certain cuts of beef and pork Coconut oil
Chicken and turkey skins Palm kernel oil
Whole-milk dairy products Palm oil
Butter  Cocoa butter
Lard  Chocolate
Some hydrogenated shortenings
 
Note: Should be consumed  no more than 7% of total daily calories as saturated fats
 
B. Monosaturated  fatty Acid - fats that are neither saturated or polyunsaturated
and are thought to play a  little part in atherosclerosis.
 
FOOD SOURCES
• Olive oil
• Peanut oil                    
• Canola oil                    
• Avocados
• Cashew nuts
 
Note:
✓ One should consume 15% of  total daily calories a day
✓ Research indicates that monounsaturated fats lower the amount of low-density
lipoprotein (LDL) or bad cholesterol in the blood, but only when they replace saturated
fats in one’s diet. They have no effect on high-density lipoprotein or good cholesterol.
 
C. Polyunsaturated  fatty Acid - fats whose carbon atoms contain only limited
amounts of hydrogen          1. Omega – 3 Fatty Acids
- help lower the risk of heart disease.
- Found in fish oils
2. Omega – 6 (Linoleic acid)
- Has a cholesterol lowering effect

FOOD SOURCES:
✓ Cooking oils made from sunflower, safflower, sesame seeds or from corn or soy
beans
✓ soft margarine
✓ fish
 
Note: should be consumed no more than 8% of the total daily calories.
 
2. GLYCEROL - is a water-soluble component of triglycerides and is in-convertible with
carbohydrates.
 
3. STEROIDS - contain sterols
 
CHOLESTEROL
− most common sterols in animals. It is present in all animal cells but is concentrated in
the bile and in the nerves. It is synthesized mainly in the liver (endogenous
cholesterol) and is also supplied in the diet (exogenous cholesterol) mostly from
the fatty portions of meat. The richest sources are the brain, glandular organs and egg
yolk
− It is not a true fat but a fat-like substance that exists in animal foods and body cells.
It does not exist in plant foods.
− Is essential for the synthesis of bile, sex hormones, cortisone and Vitamin D and is
needed by every cell in the body.
− The body manufactures 800 – 1000 mg of cholesterol a day in the liver.
− common constituent (part) of one’s daily diet because it is found abundantly in egg
yolk, fatty meats, shellfish, butter, cream, cheese, whole milk and organ meats.
 
HYPERCHOLESTEROLEMIA
- unusually high level of cholesterol in the blood also known as high serum
cholesterol. contributing factor in heart disease common in clients with atherosclerosis.
- Blood cholesterol levels should not exceed 200 mg/dl (200 milligrams of cholesterol
per 1 deciliter of blood).
 
Note: Atherosclerosis is a cardiovascular disease in which plaque (fatty deposits
containing cholesterol and other substances) forms on the inside of artery walls,
reducing the space for blood flow. When the blood cannot flow through an artery near
the heart, heart attack occurs. When it happens near the brain, stroke occurs.
 
DIGESTION AND ABSORPTION
- Although 95% of ingested fats are digested, it is a complex process.
- The chemical digestion of fats occurs mainly in the small intestine.
- Fats are not digested in the mouth.
- They are digested only slightly in the stomach where gastric lipase acts on emulsified
fats such as those found in cream and egg yolk
- Fats must be mixed well with the gastric juices before entering the small intestine.
- In the small intestine, bile emulsifies the fats, and the enzyme pancreatic lipase
reduces them to fatty acids and glycerol, which the body subsequently absorbs through
the villi.
 
Unsaturated Fatty Acids
 
TRANS FATTY ACIDS (TFAs)
- are produced when hydrogen atoms are added to monounsaturated or
polyunsaturated fats to produce a semisolid product like margarine and shortening.
- The major source of TFAs in the diet is from baked goods and foods eaten
in restaurants. TFAs raise low-density lipoprotein and total cholesterol.
 
CLASSIFICATIONS OF LIPOPROTEINS
 
1. CHYLOMICRONS
➢ first lipoprotein identified after eating.
➢ They are the largest lipoproteins and the lightest in weight they are composed of
80% to 90% triglycerides.
➢ lipoprotein lipase acts to break down the triglycerides into free fatty acids and
glycerol. Without this enzyme, fat could not get into the cells.
 
2. VERY-LOW-DENSITY LIPOPROTEINS (VLDLs)
➢ Are made primarily by the liver cells and are composed of 55% to 65% triglycerides.
➢ They carry triglycerides and other lipids to all cells.
➢ As the VLDLs lose triglycerides, they pick up cholesterol from other lipoproteins in
the blood and they become LDLs.
 
3. LOW-DENSITY LIPOPROTEINS
➢ are approximately 45% cholesterol with few triglycerides . They carry most of the
blood cholesterol from the liver to the cells.
➢ Elevated blood levels greater than 130 mg/dl of LDL are thought to be contributing
factors in atherosclerosis.
➢ Also called “Bad Cholesterol”.
 
4. HIGH DENSITY LIPOPROTEINS
➢ carry cholesterol from the cells to the liver for eventual excretion.
➢ HDL level of 60 mg/dl or more is considered protective against heart disease.
➢ They are called the “Good Cholesterol.”
➢ Exercising, maintaining desirable weight, and not smoking are all ways to increase
HDL
 
METABOLISM AND ELIMINATION
➢ The liver controls fat metabolism
➢ It hydrolyzes triglycerides and forms new ones from this hydrolysis as needed.
➢ Ultimately, the metabolism of fats occurs in the cells where fatty acids are broken
down to carbon dioxide and water releasing energy.
➢ The portion of fat that is not needed for immediate use is stored as adipose tissue
 
Cholesterol is needed by the body for the following roles:
✓ It is the precursor of 7-dehydrocholesterol, which has vitamin D activity.
✓ It is a part of the bile acids, thus it helps in the emulsification of dietary fat.
✓ It is also utilized in the biosynthesis of adrenocortical hormones, which are important
in the development of secondary male and female characteristics.
 
Besides the endogenous (i.e., “internal” sources or manufactured within the body)
cholesterol, dietary or exogenous cholesterol occurs in large amounts in eggyolk, fish
roe, oysters, brain, liver, kidney and other glandular organs. Smaller  but significant
amounts are present in animal fats (meat fats, butter fat, cream, milk fat, cream
cheese.) Since dietary cholesterol increases plasma total cholesterol and lipoprotein
cholesterol levels, it is recommended that the normal intake should not exceed
300mg/day.
 
LDL – bad cholesterol
HDL – good cholesterol
 
Ergosterol and calciferol - Are the other sterols, which are vitamin D precursors that
exist in plants and fish liver oils, respectively.
 
TERMS ABOUT FATTY ACIDS:
 
1. Omega 3 Fatty acids – are found in sea foods, some plants and some livestock
rations. However, fish and fish oils are the only concentrated source of
eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and decosapentaenoic acid
which have been shown to lower plasma triglycerides.
Ø  Omega 3 fatty acids are also thrombotic. It is believed that fish oils have beneficial
effects on coronary heart disease, wherein omega 3 fatty acids reduce platelet
aggregation and blood clots. With these fatty acids blood pressure may be lowered in
mildly hypertensive individuals.
 
2. Trans Fatty acids – also called trans-fats, one of the risk factors for cardiovascular
disease. They are made from the hydrogenation of polyunsaturated fatty acids which
changes liquid oils into solid fats. With this process, the degree of saturation of the fatty
acids is increased, linking it to higher blood cholesterol, as LDL.
 
FUNCTIONS OF FAT:
1)  Concentrated source of energy
2)  Storage form of energy-as adipose tissue, fat is the largest reservoir of potential
energy. The principal sites of adipose body fat are: the subcutaneous tissues (50%),
the surrounding organs in the abdominal cavity (45%) and the intramuscular
tissues(5%).
3) Structural component-moderate deposits of fat beneath the skin and around internal
organs, act as protective pad and give support to the organs. Subcutaneous fat also
prevents rapid heat loss from the skin, thereby conserving heat in the body.
4) Supplier of Essential Fatty Acids-an essential fatty acid (EFA) is one that can not be
synthesized in the body and should be ingested preformed or ready-made from food
sources. More appropriately, the term should be “dietary essential”. The 3 essential
fatty acids, which play important physiologic roles are: linoleic, linolenic and arachidonic
acids.
5) Carrier of fat-soluble vitamins-vitamins A, D, E and K need a fat soluble medium to
keep them in solution and to facilitate reactions, whether in foods or in the body.
Fortified margarine, fortified milk, butter and certain plant oils carry fat soluble vitamins
in the fat globules.
6) Sparer of protein, thiamin and niacin-if adequate energy is supplied by fat and
carbohydrate sources, protein is spared or saved for its unique function of tissue
building and repairing.
 
OTHER SPECIAL FUNCTIONS OF FATS:
1)  Fat has a high satiety value, i.e. it is slowly digested and depresses the hunger
sensation, i.e., it has staying quality in the stomach.
2)  It also contributes to flavor and palatability
3)  Certain lipids are emulsifying agents(e.g., lecithin) which help in the transport of
fatty substances that cannot easily pass through the cell membrane
4)  Fatty acids are precursors of a group of substances called the prostaglandins, which
participate in the regulation of blood pressure, heart rate and lipolysis.
5) It helps retain moistness in food products.
 
DEFICIENCY:

FAT MALNUTRITION
➢ Deficiency of fats per se will reduce caloric supply in the body and cause protein
catabolism. Depot fats will be withdrawn and body weight reduced.
➢ Deficiency of essential fatty acids causes retarded growth and an eczematous skin in
infants.
➢ Excessive intake of fat above the normal levels (recommended levels are from 20-
30% of total energy need) resulting in extra caloric supply leads to obesity.
 
FOOD SOURCES OF FATS:
➢ The most important food sources are the visible fats and oils such as butter,
margarine, lard, cooking oils, fish-liver oils, pork fat, suet, tallow, chicken fat.
➢ Very good sources are found in nuts, such as oilseeds and some legumes.
➢ Cream cheese, whole milk, olives, chocolate, peanut butter, and fatty fish like
sardines, avocado, pastries and fried foods, contribute significant amounts in the diet.
➢ The plant sources for unsaturated fatty acids are: corn, cottonseed, sesame,
sunflower and soybean oils; products utilizing vegetable oils; and fatty fish like tuna,
herring, salmon, sardine and mackerel.
➢ Coconut oil is low in EFA and has more saturated fatty acids compared to other
vegetable oils.
➢ Foods high in saturated fatty acids are: butterfat, whole milk, ice cream made from
whole milk, egg yolk, bacon, tallow, suet, lard, hydrogenated shortenings: fatty meats
like pork, ham certain beef cuts, poultry fat, sausages; chocolates, rich pastry and
puddings.
 
D. WATER
− Next to oxygen, water is absolutely essential to stay alive. A person cannot stay alive
after a few days without water. If about 20% of body weight is lost, death results.
Water is the most needed by the body, it is the number one nutrient. It is usually
written as H2O – 2 atoms of hydrogen and one oxygen. Water accounts for about 60-
65% of body weight for a normal adult.
 
FUNCTIONS:  life begins with water
1)  Water is nearly a universal solvent. In the blood, it carries simple sugars, amino
acid, lipoproteins, vitamins and minerals for transportation to the different tissues for
proper functioning and nourishment. It is likewise used to excrete waste products from
the lungs, skin and kidneys.
2) It acts as a lubricants of the joints and the viscera in the abdominal cavity; thus, can
protect a sensitive tissue. It moistens the eyes, nose, and mouth and hydrates the skin.
3) It is also a regulator of body temperature through its ability to conduct heat.
4) It acts as shock absorber of inside the spinal cord and amniotic sac surrounding the
fetus.
5) All of the chemical reactions require water. It serves as the transport and medium for
many biological reactions especially in digestion, absorption and circulation. It
participates in maintaining electrolyte balance.
6)  Water is a vital component of every cell, organ and tissue of the body. The highest
concentration of water is found in the active cells of muscles and viscera. The lowest
amount is in the calcified tissues (e.g., bones and teeth. Muscles contain 75% water,
bones 20% and teeth 10% only.
7) Hard water can also be a source of trace minerals such as fluorine, calcium,
magnesium and copper. At the same time, it can also be a source of toxic elements
such as lead, cadmium and other industrial wastes, as well as bacteria.
 
WATER BALANCE
➢ The amount of water taken in must be equal to the amount water output, for a
person to be in metabolic equilibrium
➢ Fluid intake is controlled by thirst, appetite, and output by the endocrine glands, as
well as the temperature of the environment.
➢ The body uses more water in the blood, saliva, intestinal, gastric, bile and pancreatic
juices than the daily intake. However, enough water is available through more efficient
conservation of water from the kidneys and intestines.
➢ It will be noted that the fluid intake is approximately equal to the urine output.
 
WATER INTAKE
➢ The amount of water needed by the body may be met by a direct intake of water
coming from water ingested as such, and from water bound with foods.
➢ The third source of water is produced inside the body called, metabolic water, which
is a result of the oxidation of food in the body.
 
WATER OUTPUT
➢ Water output is controlled by the hormone vasopressin (antidiuretic hormone or
ADH) which is secreted by the pituitary gland. Release of this hormone decreases water
excretion by the kidney by increasing the rate of water reabsorption in the tubules.
➢ Water leaves the body through several channels; the skin, as sweat and insensible
perspiration: lungs, as water vapor in the expired air; gastrointestinal tract, as feces;
and kidneys, as urine.
➢ The urine is an important medium for the elimination of excess water.
➢ Water may also be lost together with the electrolytes through tears, stomach
suction, breathing, vomiting, diarrhea, bleeding, perspiration, drainage from burns,
discharge from ulcer, skin diseases, and injured or burned areas.
 
RECOMMENDED WATER INTAKE
➢ Most RDA tables recommend 1ml per calorie for adults and 1.5 ml/calorie for infants.
This is approximately 1.5-2.5 liters or 6-10 glasses of water a day. Water intake is
derived mostly from beverages and prepared foods.
➢ Some nutritionists suggest that fluid intake be based on body weight, which varies
with age; for infants, 110ml/kg; and for 10 year-old children, 40ml/kg depending on the
environmental temperature.
 
Note:
➢ Increased water intake for athletes depending on the activity, pregnant women
because of the growing fetus and amniotic fluid, in lactation extra water is needed for
milk secretion.
➢ Concentrated urine indicates a need for more water.
 
ABNORMALITIES OF WATER IMBALANCE
➢ Over hydration or water intoxication
➢ Dehydration – may be serious if the loss is about 10% of the total body water and
fatal if the loss is from 20-22%.
 
WATER SUPPLY
➢ The quality of water supply varies depending on the locality. A glass of tap water
may be colorless but underneath it are minerals like calcium, magnesium, and in some
areas, iron and fluorine. If water is treated with softener sodium is present. Hard water
has high concentration of calcium and magnesium. It usually comes from shallow
ground.