THE VITAMINS

An overview of vitamins is necessary to appreciate why some biochemists call them “the miracle
workers”. Even in minute amounts, these organic catalysts facilitate all metabolic reactions that
use proteins, fats, and carbohydrates for energy growth and development, structural or building
cells, repair and maintenance of tissues, and thousands of other regulatory processes occurring
in the human body. While in the past, scientist have basically been concerned with the role of
vitamins in preventing vitamin related disease and their biochemical functions, today it is
recognized that vitamins have an important role in health and well-being beyond the mere
prevention of deficiency (Table 4.1). This aspect of vitamins is based on the observation that
vitamins are not only coenzymes in metabolic processes but also act as potent antioxidants and
have hormone-like functions. To date, there are 14 vitamins essential to human nutrition; 4 fat-
soluble vitamins and 10 water-soluble vitamins, including choline, which is the last one added in
2002.

Table 4.1. Role of Vitamins in the Body

Function Vitamin Examples

Cofactor or coenzyme Thiamin: Cofactor in metabolism of carbohydrates and amino

acids
of metabolism Riboflavin: Coenzyme in production of energy
Growth and repair Vitamin C: Collagen formation
Vitamin D: Bone mineralization
Antioxidant Vitamin C: Prevent oxidation in lung and gastric mucosa
Vitamin E: Prevent oxidation of lipids
Hormone Vitamin D: maintenance of serum calcium and phosphorus
Medication Niacin: Treatment of hyperlipidemia

4.1. Definition of Terms and Basic Concepts about Vitamins

Vitamins are carbon- containing, organic compounds that are needed in very small amounts in
the diet to help promote and regulate chemical reactions and processes in the body in order to
maintain health and sustain life.

All vitamins are micronutrients. As a review, micronutrients are needed by the human body in
amounts below one gram (1000 milligram) a day compared to macronutrients that are needed
in amounts above one gram/day. Many vitamins are even much smaller and are measured in
micrograms (1 mcg=one millionth of a gram).

To obtain vitamins from natural sources means they have to be ingested preferably from food.
There are a few: some are produced by the skin or bacteria in the intestine.
Deficiency diseases arise when our bodies are deprived of a vitamin for a prolonged time. To be
called a true vitamin, it must cure the deficiency disease if re-supplied in time and in adequate
amounts. To hasten treatment, the physician may prescribe supplementary sources as
medication, e.g., pills or liquid form.

Some vitamins become toxic if taken in megadoses or consumed excessively for a prolonged
period, hence the need for medical consultation. A current hot topic about some vitamins is
their role as antioxidants. To date, theses vitamins A, C, E, and beta-carotene. An antioxidant
donates electrons, which tie up free radicals that damage body cells. Diseases implicated are
cancer, age-related eye disease, and some cardiovascular and chronic ailments.

Vitamins have varying degrees and reactions to heat, oxidation, pH changes, and other
processing methods. These are explained in discussing individual vitamins.

4.2. Classification and Functions of Vitamins in General

Probably the most talked-about group of nutrients is the vitamins. Most people believe that
vitamins are important and god for them. Many also have the notion “if a little is good, more
must be better: - a fallacy which `can be dangerous when applied to vitamin supplementation.
Frequently, vitamins are classified by their solubility in fat or water. The fat-soluble vitamins A,
D, E, and K are stored by the body. If stored in excessive amounts, toxic effects occur. Water-
soluble vitamins (B complex and vitamin C) are not stored to any extent, although excessive
intakes may also cause undesirable signs and symptoms, but not as serious as observed with
the toxic effects of fat-soluble vitamins, because water-soluble vitamins can be excreted by the
kidneys.

Vitamins function primarily as catalysts – action regulator – in chemical reactions within the
body. Vitamins are essential for the release of energy within the body, for tissue building, and
controlling the body’s use food.

By themselves, vitamins do not supply energy (calories) or build tissues but many water-soluble
vitamins, notably B-complex group, participate in energy-yielding reactions in the body. In
contrast, fat soluble vitamins mainly act to regulate growth and development processes.

Each vitamin serves one or more special functions I the body that no other nutrient can.
Deficiencies, too, are specific.

Vulnerable groups at potential risk of vitamin deficiencies are the elderly, impoverished (lack of
buying power for basic food needs), alcoholics and street drug addicts, smokers, and individuals
under physiologic stress (rapid growth, pregnancy, lactation). Secondary factors that could pose
vitamin deficiencies are: specific medical conditions that interfere with adequate ingestion,
normal digestion and absorption, metabolism, and excessive excretion. Major surgeries and
wound healing, burns, fevers, intractable vomiting, prolonged chronic diarrhea and chemical
poisoning are some examples of cases that cause physical and emotional stresses.

Vitamins are measured in extremely small amount in milligrams (one-thousandth of a gram)

and in micrograms (one millionth of a gram, 28 grams = one ounce); or in International Unit
(IU). I measures the potency; the ability to promote growth or cure a deficiency disease.
An inadequacy of a minute amount of a vitamin can have far-reaching effects on body
processes and health. Too much of certain vitamins, though seemingly a small amount, can
produce harmful toxic conditions.

To understand why excessive doses of vitamin supplements are potentially harmful, consumers
need to know that vitamins are chemical substances, which have other chemical activities in the
body in addition to vitamin activity. To achieve vitamin activity in the body, the vitamin – acting
as part of a coenzyme – must associate with a protein – called an apoenzyme. Together they
form an enzyme known as a holoenzyme – which has the vitamin activity in the body.

Once the apoenzyme in the body cells is saturated – filled-up with the coenzyme (the vitamin),
no further activity can possibly be achieved by adding any amount of the vitamin. The excess
coenzyme then serves as a chemical substance, which in most cases is damaging to the body.
This is why overdosage of vitamin supplements cannot benefit the body and may in fact be
harmful. As research continues, more answers will be found as to how much is too much.

Holoenzymes are made only within the body. Enzymes consumed are digested, thus lose their
enzymatic capabilities and serve no nutritional purpose.

4.3. The Fat-soluble Vitamins (A, D, E, K)

All fat-soluble vitamins do not contain nitrogen in their chemical composition, compared with
water- soluble vitamins that have nitrogen in their molecule, but not as an amino acid. Other
common characteristics of fat-soluble vitamins are:

 They are carried by lipid/fat that requires bile for absorption.

 An advantage over water-soluble vitamins is; fat-soluble vitamins are more stable to
heat and cooking.

 A disadvantage of fat-soluble vitamins is, they cannot be excreted in the urine and
excess amounts are stored in body tissues. With water-soluble vitamins, there is a
saturation point of vitamin load or level in the tissues and bodily fluids, above which,
excess is excreted in the urine.

 There are several forms of fat-soluble vitamins that are utilized by the body.

 Each of the fat-soluble vitamins has different functions, sources, specific deficiency
disease, and toxic effects in excessive amounts.

4.3.1. Vitamin A

Vitamin A comprises a large family of fat-soluble compounds- retinols and carotenoids. These
carotenoids are precursors of Vitamin A and the body converts it into active vitamin A form. The
retinols are already active vitamin A (i.e., performed vitamin A). Precursors or provitamins are
compounds that can be changed to the active vitamins; they are potential vitamins, e.g.,
carotenes and cryptoxanthin are precursors of vitamin A; preformed vitamins are naturally-
occurring that are in active form and ready for its biological role.

Vitamin A functions

Vitamin A is vital for vision, growth, the immune system, and reproduction. It is essential for
the integrity of the mucous membranes throughout the body ad necessary for healthy skin,
bone and tooth growth.

Vitamin A is best known for its vital role in promoting and maintaining good vision. Interestingly
enough, only one-thousandth of the vitamin A in our bodies is found in eyes; most is in the
blood stream and tissues. The vitamin A that is not flowing through our system is stored in the
liver.

Vitamin A has an important role in the building of body cells. It is essential for the growth of
children and the development of babies before birth. It is needed for bone growth and healthy
tooth structure. In the formative years, it is important for spacing of teeth, tooth enamel, and
formation of bones.

Vitamin A is essential for healthy skin and epithelial tissue found in the inside surface of the
mucous membranes, the lining of mouth, throat, lungs, stomach, intestine, urinary tract`, and
the reproductive tract. It maintains the normal structure and functioning of the mucous
membranes which forms the inner linings of the body. It maintains the stability of the cell
membranes; helps ensure a normal output of thyroxin from the thyroid gland, helps the
manufacture red blood cells.
It plays an important role in the body’s immune reaction and some forms of vitamin A function
as important antioxidant. As antioxidants, betacarotene and other carotenoids protect the body
from disease and the actions of the unstable and highly reactive molecules called free radicals.
Beta-carotene works with vitamins C and E in the body to build a strong immune system.

Measurement and Recommended Intake

Vitamin A activity is measured in retinal equivalents (RE) because various forms of vitamin have
different activity levels.

One RE Vitamin (in mcg) equals:

10.00 IU from plant foods (average estimate for avg. carotenoids)
6.00 IU from beta-carotene (carotenoid with the most A activity)
12.00 IU from alpha-carotene or cryptoxanthin (carotenoids)
3.33 IU from animal foods and chemical form used to fortify foods
3.50 IU from cheese (a mixture of retinols and carotenoids)
4.10 IU from yogurt and milk (a mixture of retinols and carotenoids)

Results of nutrition surveys in the Philippines showed that 87% of retinol comes from plant
sources, particularly beta-carotene. Only 13% comes from animal sources or preformed vitamin
A. The 2002 recommended energy and nutrient intake (RENI) values for vitamin A are as
follows:
 µg RE
Males
19 years and over (59 kg. body weight 550
Females
19 years and over (51 kg. body weight) 500
Pregnancy (+300) 800
Lactation (+400) 900
Infants (6-11 mos.) 400
Children (1-9 yrs.) 400
Boys and Girls (10-18 yrs.) See RENI in Appendix
B

Deficiency and Toxicity

Xerophthalmia [literally “dry eye”] is a cause of blindness that results from vitamin A deficiency.
The specific cause is linked to a lack of mucus production by the eye, which then leaves it at a
greater risk of damage from surface dirt and bacteria.

Vitamin A deficiency causes changes in the integrity of epithelial cells that lead to kin alterations
known as follicular hyperkeratosis or “goose-bump flesh.” where small raised bumps of skin
surround the hair follicles on the body.

Individuals who dine regularly on hamburgers, French fries, soft drinks, snack, and candies
(and eat few fruits or vegetables) may also run a risk of vitamin A deficiency. Deficiencies of
other nutrients, such as vitamin E, iron, zinc, and protein, may adversely affect the absorption,
transport, storage, and utilization of vitamin A. Elderly people suffering from type 2 diabetes
often have a decline in vitamin A blood levels due to their age and despite sufficient dietary
intake.
Toxicity or adverse effects are only from retinol form of vitamin A. A person cannot overdose on
vitamin A from plants (the carotenoid or beta-carotene form), because the body controls the
amount it absorbs. However, carotenemia may result from excessive carotene in the blood
characterized by an abnormal yellow color of the skin and plasma. It is not toxic and is
reversible.

An adult may have problems from megadoses in supplements taken over a period of time
(approximately 25,000 IU or 7,500 RE per day of the retinal form). Toxic effects are liver
damage, headache, vomiting, abnormal vision, constipation, loss of hair, loss of appetite, low-
grade fever, bone pain, sleep disorder, dry skin and mucous membranes. A pregnant woman
who takes more than 10,000 IU a day doubles her risk of giving birth to a child with birth
defects.

Chronic vitamin A toxicity leads to liver damage. Individuals with high alcohol intake or
preexisting liver should avoid excess preformed vitamin A from supplements.

Food Sources and Cooking/Processing Stability

Animal foods and vitamin A-fortified foods supply the retinoid form of vitamin A or preformed
vitamin A. It is easily absorbed and excess is stored in the liver and fat tissue. This is the only
form that can become toxic if taken in extremely large quantities, such as from supplements.
Natural sources are primarily liver and dairy products, and the chemical form is used to fortify
foods like breakfast cereals.

The carotenoids are precursors of vitamin A and are found in fruits and vegetables and in small
amount in dairy foods. See Figure 4.1.

There are hundreds of carotenoids and approximately 10% of them have some vitamin A
activity. The most active vitamin A precursor is beta-carotene. The value of carotenoids,
however, may exceed vitamin A activity. Beta-carotene is responsible for the rich, yellow-
orange-red pigment of fruits and vegetables, but carotenoids are plentiful in dark green
vegetables in which chlorophyll masks the orange color.

Vitamin A destroyers include: tannic acid found in black tea; nitrates and benzoate from
preserved food; aspirin, barbiturates; artificial lemon flavoring called citral, ferrous sulfate, and
iron supplement; and pollutants such as nitrates from high nitrogen fertilizers, nitrogen dioxide,
and ozone.

As a fat-soluble vitamin, the body’s absorption of vitamin A is substantially reduced in very low-
fat diets. Mineral oil (sold as a laxative) and some fat replacers are not rapidly absorbed by the
body and will attach to the vitamin A and carry it unused from the body.

General cooking retention is fairly good and ranges from approximately 70 to 90%; however,
high temperature in the presence of oxygen (air) will destroy much more vitamin A. Preliminary
research finds that foods cooked and canned with little contact with air have high nutrient
retention rates for carotenoids. However, they oxide and lose value when they have been
dehydrated or freeze-dried in the presence of air. Retention is high if the drying or freeze-
drying process is closed to air exposure.

Because vitamin A and carotenoids are fat soluble, more is available if cooked in little oil, butter
or margarine. Preliminary information finds that far more beta-carotene is bioavailable in
cooked carrots than in raw. The carotenoid lycopene in cooked and processed tomatoes is more
easily absorbed than in raw tomatoes.

4.3.2. Vitamin D ( Calciferol, Ergocalciferol, Cholecalciferol, 7-Dehydrocholesterol)

Calcitriol (technically a hormone) is the final active form of vitamin D. It is also known as 1,25-
dihydroxyvitamin D or 1,25-dihydrocholecalciferol. Ergocalciferol (D2) is the form found in food.
Cholecalciferol (D3) is biologically inert and is converted to calcitriol in the liver. The precursor,
7-dehydrocholesterol present in the skin, becomes vitamin D upon exposure to ultraviolet light
or sunshine. Note that the precursor is a form of cholesterol.

Vitamin D functions

Vitamin D is vital for the proper mineralization of bone and helps maintain proper blood levels
of calcium and phosphorus. Vitamin D regulates the efficiency of the small intestine to absorb
calcium and phosphorus, and promotes the growth of strong bones.
Vitamin D signals the GI tract to absorb more calcium, the bones to release more, and the
kidneys to retain more in the body. Thus, vitamin D maintains the blood calcium and
phosphorus at needed levels.

This is an unusual nutrient in that it is photosynthesized by the body from the action of sunlight
(ultraviolet B radiation) on the skin. Given enough sun, a person will have sufficient vitamin D.
A daily 15-20-minute walk in the morning sun stimulates the body’s production of vitamin D.
About 100 nmol/L (nanomoles per liter of blood) is considered normal. Too much sun breaks
down collagen and elastin proteins that form the skin, leaving it thinner and more wrinkled as
you age. Darker skinned people require longer exposure to sunlight than lighter skinned people
to make the same amount of vitamin D – approximately 3 hours versus about 30 minutes.

Measurement and Recommended Intake

Because both sunlight and dietary intake play a role in providing vitamin D, intake is expressed
in international units (IUs) or micrograms (mcg or µg). One IU = 0.025 mcg; or one mcg of
vitamin D = 40 IU.

The FAO/WHO Expert Group recommends the use of vitamin D3 or cholecalciferol in mcg in
measuring vitamin D values. To calculate µg cholecalciferol, divide vitamin D I.U. by 40.

The RENI for vitamin D is 5 µg for infants, children, adolescents and adults 19-49 years; 10 µg
for male and female 50-64 years of age; and 15 µg for older persons (65 years and over). See
Appendix B for details on RENI values. Minimum requirement for vitamin D is easily met by an
ordinary mixed diet and by normal exposure to sunlight.

Deficiency and Toxicity

People who completely avoid sunlight or who do not consume sufficient dietary vitamin D are at
risk of deficiency. The body’s production of vitamin D is reduced by the application of
sunscreen, and it will vary according to the intensity of the sun, as affected by geographical
latitude, time of day, and season.

Vitamin D insufficiency causes secondary hyperparathyroidism, rickets in children and

osteomalacia and osteoporosis in adults. It may also be associated with an increased risk of
colon cancer, breast cancer, prostate cancer and other cancers and an increased risk for severe
acute lower respiratory illness.

Rickets is the disease that results from inadequate exposure to sunlight or inadequate dietary
intake of vitamin D as an infant. It is characterized by bowed legs, narrow rib cages, and other
deformities. To date it still affects many children worldwide. It has also been observed in
children with fat malabsorption and vegetarian children who do not consume milk.

With an “indoor lifestyle”, many people do not get sufficient exposure to sunlight to create
enough vitamin D for their needs, which can result in the adult form of rickets called
osteomalacia. Curvature of the spine and bowed legs are only some of the results of bone
softening due to vitamin D deficiency.
Vitamin D toxicity can occur by consuming supplements only. Toxic effects are potentially
severe and can include calcification of soft tissues, reduced kidney function because of
calcification, and central nervous system disorders. A megadose of 2,000 IU a day can cause
irreversible damage for the kidneys and heart. Smaller doses may cause muscle weakness,
headache, nausea, vomiting, high blood pressure, retarded physical growth, and mental
retardation in children, and fetal abnormalities. Toxicity cannot occur when vitamin D is formed
from sunlight because the body controls the amount formed.

Food Sources and Cooking/Processing Stability

Self-synthesis of vitamin D through exposure to sunlight is the easiest and safest for most
people because the body regulates the amount it creates. For those who are very sensitive to
the sun, food fortified with vitamin D or the careful use of supplements are alternatives.

The very few foods that have vitamin D naturally are fish liver oils, fatty fish, and egg yolks
from chickens that have been fed vitamin D.

Some foods have been fortified to provide dietary vitamin D, such as milk, some yogurts, some
infant formulas, some margarine, and some fortified cereals. ( Figure 4.2).

Vitamin D is very stable to heat, aging and storage.

4.3.3. Vitamin E (Alpha Tocopherol, other Tocopherols, & Tocotrienols)

Vitamin E is comprised of eight forms: the alpha, beta, gamma, and delta tocopherols and the
alpha, beta, gamma, and delta tocotrienols. The most active form is alpha-tocopherol. Other
forms are considered less active, but there is evidence that some forms may work better in the
presence of others, a synergy that cannot be quantified in the terms of activity. Alpha and
gamma tocopherol together may be more effective than one alone.

Vitamin E Functions

Vitamin E, an important antioxidant, providing special protection of polyunsaturated fatty acids

(PUFA), vitamin A, carotenoids, and hormones of the adrenal, pituitary and sex glands. It
stabilizes cell membranes, promotes healing of tissues, protects red and white blood cells, and
regulates oxidation reactions.
Vitamin E acts as an antioxidant to prevent cell-membrane damage. It helps to protect
unsaturated fats in the body, especially the polyunsaturated fats (PUFA) from oxidation. It also
detoxifies radicals (destructive substances).

Vitamin E aids in the growth on new tissues and the healing of damage tissue from surgery or
burns. It protects red blood cells from hemolysis.

In older adults, it improves the immune response. Vitamin E appears to prevent the oxidation of
the bad cholesterol (LDL) in the blood streams. When LDL is oxidized, it is more likely to
promote to build up of fatty plaque in the artery walls (atherosclerosis).
It is important to know that originally, vitamin E was called the “antisterility vitamin.” This was
proven for rats but not for humans. Hence, any such claim of a food or substance for humans is
false or unfounded.

Measurement and Recommended Intake

The total weight of vitamin E present, without regard for activity or the various forms, is simply
called total vitamin E. As a reference, 1 IU of vitamin E is the same as 0.67 mg of vitamin E.
The requirement for vitamin E is based on the 2R-stereoisomeric forms of alpha-tocopherol only
that includes RRR-alpha-tocopherol, which occurs naturally in foods, and the 2R-streoisomeric
forms that occur in supplements and fortified foods (all racemic alpha-tocopherol). Other forms
of vitamin E do not contribute toward meeting the requirement.

Previously, alpha tocopherol equivalents (TEs) is used for dietary recommendations. Using
alpha tocopherol as the standard of one (1), the amount of each vitamin E component is
weighed according to its activity factor, as listed next. Then all the weighed components of E
are added together.
1 mg alpha tocopherol = 1.00 α-TE
1 mg β tocopherol = 0.50 α-TE (assays range from 0.25 - 0.50)
1 mg ϒ tocopherol = 0.03 α-TE (assays range from 0.10 - 0.35)
1 mg ∆ alpha tocopherol = 0.03 α-TE
1mg β tocotrienol = 0.05 α-TE

The Philippine RENI for Vitamin E is expressed in mg alpha tocopherol equivalent (α TE). For
adult males and females (19 years and over) the RNI is 12 mg. For the other age groups, refer
to Appendix B. In the U.S. the minimum adult requirement is 4 mg α-TE or 6 IU per day. Alpha-
tocopherol equivalents should be converted to milligrams of alpha-tocopherol. The natural form
of vitamin E is D-tocopherol. The synthetic version is a “mirror image” version called L-
tocopherol, and has about 74% of the activity of the natural vitamin.

Deficiency and Toxicity

Deficiencies are rare and are usually associated with diseases of fat malabsorption such as
cystic fibrosis and in individuals consuming very low-fat diets for a prolonged period. A
continual diet of processed convenience foods over a long period may contribute to vitamin E
deficiency.

When blood concentration of vitamin E is in severe deficiency state, the red blood cells tend to
break open. A prolonged deficiency state can cause neuromuscular dysfunction with loss of
muscle coordination and impaired vision. If untreated, the conditions may become permanent.

Extremely high doses of vitamin E may interfere with blood clotting and enhance the effects of
drugs used to oppose blood clotting, such as aspirin, or anticoagulant. Large amounts (more
than 400 to 800 IU a day) may cause upset stomach and dizziness. Persons vulnerable to
toxicity are the hypertensives and those with chronic rheumatic heart disease.

Food Sources and Cooking/Processing Stability

Vitamin E is predominantly found in vegetable and seed oils, nuts and seeds, green and leafy
vegetables and some fruits. Alpha-tocopherol is the main source found in supplements and in
the European diet while gamma-tocopherol is the most common form in the American diet.

Best sources of vitamin E are wheat germ oil, sunflower seeds, filberts, sunflower seed oil,
safflower oil, cottonseed oil, peanuts and peanut butter, almonds turkey liver, cod liver oil, palm
oil, soybean oil, corn oil, canola oil, wheat germ, other nuts, and selected fruits and vegetables.

Because oil is a major ingredient of margarines and salad dressings, many of these products
contain some vitamin E as well.

Excellent sources of the gamma tocopherol form of vitamin E include palm oil, soybean oil,
rapeseed oil (canola), tofu, and several nuts (almonds, cashews, pumpkin seeds, and walnuts).

Tocotrienols are only minor components in plants, although several sources with relatively high
levels include palm oil, cereal grains and rice bran.

Vitamin E is fairly stable at regular cooking temperatures, but high frying temperatures will
destroy more of the vitamin. It is not stable to alkalis.

The milling of whole grains into flour takes out a high percentage of vitamin E, and the
bleaching of flour eliminates any vitamin E remaining. If a person ingests mineral oil, it will
absorb vitamin E and carry it unused out of the body.

4.3.4. Vitamin K (Napthoquinone- Phylloquinone, Menaquinone, Menadione)

Vitamin K is a family of structurally similar fat-soluble 2-methyl- 1, 4-napthoquinones,

including phylloquinone (vitamin K1), menaquinones (vitamin K2), and menadione (vitamin K3).

All members of the vitamin K family possess the identical napthoquinone skeleton with various
side chains that distinguish them.

The best-known member of the vitamin K family is phylloquinone, also known as phytonadione
because of its intimate relationship with photosynthesis in plant leaves. Phylloquinone is the
naturally occurring form found in many higher plants as well as algae, with the highest
concentrations in green leafy vegetables.

Menaquinone is less active compared to phylloquinone. It is the form synthesized in the colon
by bacteria.

Menadione and other synthetic vitamin K are water-soluble. Injected Vitamin K has to be
soluble in the blood. An example is menadiol sodium diphosphate.

Vitamin K is unique in that bacteria in the GI tract can synthesize it. Bacterial production alone
is not enough to meet the body’s total need, however, so it is important that the body gets
adequate of amounts of vitamin K from the diet.
Fat-soluble vitamins are dependent on the presence of other fat-soluble vitamins in order to
function. For example, three of the four fat-soluble vitamins (A, D, K) play important roles in
bone remodeling; Vitamin K helps in the synthesis of a specific bone protein, and vitamin D
regulates the synthesis.

Vitamin K functions

The K comes from the Danish word for coagulation, spelled koagulation. Vitamin K is a part of
the synthesis of blood clotting proteins and a protein that regulates blood calcium. To make
blood clot, it takes 13 different proteins plus calcium.

Vitamin K is essential for the synthesis prothrombin and at least five other clotting factors to
produce fibrin, the protein structure of blood clots. Blood clots are needed to prevent the
effects of injuries and the normal wear and tear that causes small rips in blood vessels.

This vitamin is also important for the synthesis of other proteins in the bone, plasma, and
kidney. Long-term studies revealed the role of vitamin K in bone formation by activating three
different proteins needed to form new bone cells (Framingham, MA).

Vitamin K has been linked also to two of the most important health issues, bone health and
cardiovascular health. This action specifically centers on calcium utilization – implying that there
is concurrent arterial calcification and bone loss when metabolism of dietary calcium is
inadequate. This is called the Calcium Paradox. Vitamin K dependent proteins called the Gla
proteins, including osteocalcin and matrix Gla protein, specifically address the calcium paradox
by promoting bone density, inhibiting bone loss and inhibiting vascular calcification.

Natural Vitamin K2 has been shown in laboratory experiments, population based studies and
clinical trials to be much more effective than K1 in preventing bone loss, promoting bone
integrity, significantly reducing the incidence of arterial calcification and promoting
cardiovascular health.

Measurement and Recommended Intake

The Philippine RENI for vitamin K is 59 µg for male adults (19 years and over) 51 µg for female
adults (19 years old); 13-35 µg/day for children (1-12 years) and 49-50-140 µg/day for
adolescents (13-18 years). The greatest need for vitamin K may be during the time immediately
after birth.

The recommended nutrient intake in the United States and the United Kingdom is based 1
mcg/kg body weight with adults intakes estimated at 80-300 mcg/day.

Deficiency and Toxicity

Vitamin K deficiency is seldom seen except in an unusual combination of circumstances.

Prolonged antibiotic drug therapy, especially sulfa drugs, can kill intestinal bacteria that make
vitamin K, thereby causing a deficiency. Deficiencies may also occur whenever fat absorption is
impaired, such as in diarrhea or when bile production is faulty.
 The only major sign of Vitamin K deficiency is that the blood cannot clot, coagulation is lacking,
resulting in hemorrhagic disease. However, vitamin K deficiency is not the only cause of
hemorrhagic disease, because there are other factors involved with normal blood clotting as
well.

Because the body can store this vitamin, deficiency is unlikely; the body can rely on its stores
when dietary intake is low.

Newborn infants have a sterile digestive tract at birth, and vitamin K in breast milk is minimal;
therefore, newborns may be susceptible to vitamin K deficiency, which may be seen as
hemorrhages. Most babies born in hospitals are given an injection of vitamin K at birth to
protect them from possible deficiencies. Infant formulas are fortified with vitamin K for this
reason.

Toxicity is rare, but it may be possible to intake too much of the supplement form. Since
vitamin K is fat-soluble and stored in the liver, the body cannot excrete the excess. Excessive
doses can result in the clotting and breaking of blood cells. One of these symptoms of toxicity is
jaundice.

Food Sources and Cooking/Processing Stability

The best food sources are dark green vegetables (especially sili, amorgoso or ampalaya,
malunggay, mustasa leaves, kale, broccoli, spinach, and loose-leaf green lettuce). The word
“phyllo”-quinone signifies green plant sources for vitamin K1 or phylloquinone. Other
sources include eggs (the egg yolk), milk, strawberries, avocados, tomato sauces, and other
vegetables and fruit. See Figure 4.3.

Vitamin K is fairly stable, although sensitive to light and irradiation. Thus, clinical preparations
are kept in dark bottles.

4.4. The Water-soluble Vitamins

There are 10 (ten) water-soluble vitamins: ascorbic acid or vitamin C and nine B-complex
vitamins known to be essential for the human body. The B vitamins are thiamin (B 1), riboflavin
(B2), niacin (B3), pyridoxine (B6), folacin, pantothenic acid, cyanocobalamin (B 12) and biotin.
Choline was recently added to the list. Therefore, they must be included in the daily diet. A few
other vitamin-like compounds (e.g., inositol, carnitine, coenzyme Q), are required by animals,
but are still under study for human nutrition. Only the known essential water-soluble vitamins
for human nutrition will be discussed in this Chapter.

The general characteristics of water-soluble vitamins have been compared with those of fat-
soluble vitamins. Water-soluble vitamins do not have precursors. However, tryptophan, an
amino acid, can be converted to niacin. They are not stored significantly in the body. Any
excess is excreted via the kidneys. A deficiency disease is also specific when a water-soluble
vitamin supply is inadequate, but it develops faster and signs and symptoms appear faster than
for a fat-soluble vitamin.
All vitamins are organic micronutrients that do not supply energy. Only water-soluble vitamins
contain nitrogen in their chemical composition, but not as amino acids like in proteins.

Most authorities consider the emergence of vitamins as the beginning of nutrition as a distinct
science. Historically, the word vitamin was first called “vitamine” originated by Casimir Funk in
1912. He was searching for the constituent in rice bran that cured beriberi. The word “vita”
signified its vital role and “amine” indicated that the missing substance contained nitrogen.

Later years proved that all the “accessory food factors” (old term for substances needed in
minute quantities) that cured scurvy, rickets, and pellagra were not amines, thus the last “e”
was dropped. Thereafter, for over 100 years now, we have been using the word vitamins.

Vitamin B was first thought to be a single growth substance, but eventually it proved to be not
one, but several different, though functionally related, growth factors and coenzymes.
Consequently, the B-complex vitamins were numbered but naming them by its chemical
composition is preferred. Both nomenclatures are given in this chapter.

4.4.1. Vitamin C (Ascorbic Acid)

Vitamin C or ascorbic acid is a very reactive vitamin. It is convertible into different forms with L-
ascorbic acid and L-dehydroascorbic acid as the most state. Further oxidation of L-ascorbic acid
produces diketogulonic acid that has no biologic value.

Interestingly, the chemical structure of ascorbic acid is quite similar to glucose. Almost all plants
and animals can manufacture vitamin C from glucose, except human beings, guinea pigs,
monkeys, a rare fruit bat, and a rare bulbul bird. Man and the other 4 animals do not have the
enzyme that converts glucose to gulonic acid then to ascorbic acid. Hence, they must be
supplied daily in food.

Vitamin C Functions

Vitamin C is essential for the formation and maintenance of the protein collagen, the base
structure of all connective tissue in the body (blood vessel walls, scar tissue, matrix for bones
and teeth, etc.). Bones and teeth continually need vitamin C to repair connective tissues. It
keeps capillaries and other blood vessels strong, thus preventing anemia and capillary
hemorrhages

Vitamin C is necessary in the metabolism of proteins (e.g., phenylalanine and tyrosine) and for
the synthesis of hormones and neurotransmitters. It aids in the production of the hormones:
epinephrine and norepinephrine, insulin and thyroxin. These last two hormones regulate
metabolism.

Vitamin C builds the body’s resistance to infections. As a major antioxidant, it strengthens

resistance to infections and counters the adverse effects of free radicals. Vitamin C serves as a
“bodyguard” by becoming oxidized first to protect other substances and nutrients (e.g.,
vitamins A, E, folate) from a similar fate. It is sometimes added to food products (i.e., an
intentional food additive) to protect them from oxidation or discolorations, as well as to improve
overall nutritional value.
It helps in coping with severe stress by facilitating the production of steroid hormones,
especially the adrenocorticohormones.

Vitamin C is necessary for the healing of bone fractures, wounds, cuts, burns and lesions in the
mouth and gums.

It enhances absorption of iron from foods.

Measurement and Recommended Intake

The unit of measurement for vitamin C is in terms of milligrams (mg).

In general, males need more vitamin C than females. Physiological stresses (e.g., pregnancy,
lactation) and other stress factors like surgery, illness, infection, shock and injuries increase the
need for vitamin C.

The Philippine RENI (Appendix B) for vitamin C in mg/day are as follows:

Adults (19 year and over)

Males 75 Boys:
Females 70 10-12 yrs. 45
Pregnancy 105 13-15 yrs. 65
Lactation 120 16-18 yrs. 75
(1st 6 mos.) 105 Girls:
(2nd 6 mos.) 100 10-12 yrs. 45
Children: 1-3 yrs. 30 13-15 yrs. 65
4-6 yrs. 30 16-18 yrs. 70
7-9 yrs. 35 Infants (6-11 mos.) 30

Deficiency and Toxicity

A severe deficiency can result in scurvy, which is how the vitamin was eventually discovered
and named. The name ascorbic acid was derived from the anti-scorbutic (anti-scurvy) factor.

Because vitamin C is the major antioxidant present in the airway surface of the lungs, higher
intake of vitamin C appears to offer protection for smokers, persons exposed to environmental
oxidants (pollution), and adults with symptoms of asthma.

There is no evidence of harm for persons who take regular supplemental doses of 500 to 1,000
mg a day (or 1 gram). On the other hand, proven benefits above 100 mg a day are not
obvious.

Massive doses of vitamin C may conflict with anti-clotting medications, may interfere with some
tests used to determine diabetes, and are a problem for persons with iron overload
(hemochromatosis) because vitamin C enhances iron intake. Megadoses of vitamin C at 2,000
mg or more a day interfere with vitamin B12 utilization.
Food Sources and Cooking/Processing Stability

It is important to emphasize at this point that vitamin C is the “vitamin of freshness”, i.e.,
natural food sources in its freshest state has higher vitamin C content than after exposing it to
air, heat, light and alkali. Vitamin C is more readily destroyed than the other vitamins. It is table
in growing plants, but when they are cut or bruised, an enzyme is activated that destroys the
vitamin. Blanching vegetables inactivate the enzyme. Vitamin C is also easily destroyed by
exposure to air, heat, iron and copper pans, and will leach easily into cooking water.

Citrus fruits (oranges, suha or pomelo, tangerine, calamansi, dayap, lemons) are well-known as
best sources for vitamin C. Other excellent fruit sources include guava, papaya, passion fruit,
kiwi, cantaloupe and other melons, mangos, bananas, guyabano, duhat and berries. See Figure
4.4.

Vegetable sources include fresh raw leafy vegetables, tomatoes, red peppers and green
peppers, dark-green vegetables of all kinds, like the leaves of ampalaya, malunggay, sili,
saluyot, camote, spinach or kulitis, kangkong, alugbati, and gabi leaves. When cooked properly,
vitamin C contents of the vegetables will still be retained in amounts that will contribute to the
total vitamin C daily requirement.
Dark green leaves are more nutritious than pale leaves. For example, dark green lettuce leaves
and Romaine lettuce or interior of a Baguio lettuce head. Quick freezing retains more vitamin C
than canning or cooking in syrups or water. Use minimum amount of water, or steaming is
preferred to boiling. Microwave ovens may be used for steaming.

Poor sources are dairy products, grains and grains products, nuts, meats, cooked dried beans
and peas. Many luncheon meats use a form of vitamin C as preservative, but it is not a form
that is bioavailable to humans.

Vitamin C is most stable in acid fruits (they don’t have the destroying enzyme). Refrigerated
citrus fruit juices stored in a sealed container with a small airspace will refrain most of their
vitamin C; however in the presence of air (oxygen), juices will retain less vitamin C. Loss of
flavor usually parallels loss of nutrients. To reduce oxidation and conserve nutritive value, foods
high in vitamin C should be used promptly kept refrigerated or frozen, and cooked quickly in
small amounts of liquid or by steaming. Cut up fruits and vegetables when ready to cook.

4.4.2 Thiamin (Vitamin B1)

Thiamin (no letter e at the end) is essential for helping cells convert carbohydrate into energy
and necessary for healthy nerve cell, brain, and heart function. Thus, the other names for
thiamin are: the “morale” vitamin, antineuritic vitamin, and anti-beriberi factor.

Thiamin is absorbed from the small intestine. Any excess is excreted in the urine because
thiamin is water-soluble and is not stored to any degree.

Thiamin Functions

Thiamin is essential for making the energy in food available to the body as an integral part of
the coenzyme factor TPP (thiamine pyrophosphate). It works with other “B” vitamins in the
many stages of metabolism to convert carbohydrate into a usable form of energy (glucose). In
this role, it is pivotal in providing fuel to the brain, heart, nerves, and other body cells.

More thiamin is needed if you are very active and consume a high calorie diet, or if a high
percentage of your calories come from carbohydrates.

Thiamin also plays an important, but less understood role in regulating normal nerve
transmissions. Reflexes and numbness of extremities are impaired with lack of thiamin. It helps
maintain good appetite and good muscle tone especially of the gastrointestinal tract.

Measurement and Recommended Intake

Thiamin is measured either in milligrams (mg) or micrograms (mcg). Because thiamin is

essential to the metabolism of energy (calories), the recommended amount of thiamin is
indexed to the calories consumed at 0.5 mg thiamin/1000 kcal/day with a 1 mg/day minimum.

The Philippine RENI for thiamin measured in mg/day are as follows:

Adult Men, 19 years & over 1.2

Adult Women, 19 years & over 1.1
Pregnant 1.4
Breastfeeding 1.5
Adolescents See RENI Appendix B

The recommended intake values are estimates for healthy individuals. Amounts may increase
for individuals who are very athletic and active, and those persons with certain health
conditions, such as those being treated with dialysis individuals with malabsorption syndrome,
women carrying more than one fetus, or those who are nursing more than one infant, and
persons with chemical dependency or drug addictions.

Deficiency and Toxicity

Because the brain and nervous system rely on glucose for energy, they are sensitive to a
shortfall of this vitamin.
Mild deficiencies result in the inability to concentrate, poor coordination, irritability, depression,
and muscle weakness. Major deficiencies produce far more severe symptoms: edema, atrophy
of leg muscles, motor weakness, peripheral nerve changes, paralysis, and heart failure.
The clinical condition of severe, prolonged deficiency, called beriberi, led to the discovery of this
vitamin. Infantile beriberi occurs in infants two to five months of age whose main food is milk
from a mother’s breast suffering from beriberi. The baby has edema especially of the legs, and
shows cyanosis (bluish discoloration), loss of voice, and difficulty of breathing. Life is
threatened and severe cases result in death.

Thiamin is needed to metabolize alcohol, and concurrently, alcohol decreases the absorption of
thiamin. Also at risk are those who consume large quantities of polished white rice that is not
enriched or baked goods made with refined flours and cereals lacking in thiamin and are not
enriched. Deficiencies may be created with a continual and prolonged diet for only dry snacks
(such as corn chips and pretzels that are not made with enriched flour), or a continual diet of
soft drinks and candy (a low-nutrient, high calorie diet).

There have been no reported cases of thiamin toxicity from foods. Thiamin toxicity is not a
problem because renal clearance of the vitamin is rapid.

Thiamin supplementation for beriberi under a physician’s care shows dramatic results.
Adults with mild case respond to 10 mg of thiamin taken orally three times a day. A daily dose
of 50 to 100 mg per day shows dramatic recovery: Edema is reduced or disappears within 72
hours, numbness and neurological signs within 24 hours, and cardiac symptoms within 48
hours. Thiamin therapy for infants and children will vary with age and severity of beriberi as
prescribed by the pediatrician.

Because there is teamwork among the B complex vitamins in metabolism, and most patients
suffer from multiple deficiency diseases, B-complex vitamin preparations may be prescribed by
some physicians.

Food Sources and Cooking/Processing Stability

Excellent sources of thiamin include liver and other glandular organs, lean pork and ham, egg
yolk, shellfish, enriched grain products (breads, pasta, and fortified breakfast cereals), whole
grains (found in the bran and germ), most nuts, soy and soy products, cooked dried beans
especially munggo, patani, and kadyos.

Various leguminous vegetables like bataw, sitsaro, habitsuelas, and some fruits also contribute
some thiamin. Check your food consumption tables for details.

Thiamin is not heat-stable and, therefore, is one of the vitamins most easily destroyed by
cooking or by the milling of grains. It is a water-soluble vitamin and will dissolve into the
cooking liquid. If the liquid or stock is used, there should be fairly complete retention.

4.4.3. Riboflavin (Vitamin B2)

Riboflavin is a water-soluble, yellow fluorescent compound. Its official and chemical name is
riboflavin indicating it has ribose (a pentose, a 5-carbon simple sugar) and flavonoid, a yellow
pigment. Old names include vitamin G, lactoflavin ovoflavin, hepatoflavin and verdoflavin. The
last four traditional names originated from the rich food sources of riboflavin: milk, eggs, liver,
and green vegetables, respectively.

Riboflavin is absorbed in the small intestine, with any excess excreted in the urine. The greatest
concentration of riboflavin occurs in the liver and kidneys, but body reserves are limited. Daily
food sources of riboflavin are needed because this is a water-soluble vitamin, which must be
replenished at frequent intervals.

Riboflavin Functions

As a component of several different enzymes, riboflavin is essential to many steps in the

metabolism of carbohydrates, fats and protein. It helps cells convert carbohydrates into energy
and is essential for cell growth, production of fed blood cells, and healthy skin and normal
vision.

It is necessary for building and maintaining body tissues, for making red blood cells, for helping
the body protect itself from common skin and eye disorders, and for synthesizing
corticosteroids. Riboflavin is needed to release the body’s stored energy for use. People who are
more active need more riboflavin. Riboflavin works with the other B vitamins and is essential for
the activation and functioning of vitamins B6, folate, niacin, and vitamin K.

Measurement and Recommended Intake

Riboflavin is measured in terms of milligrams (mg) and micrograms (mcg).

Riboflavin requirement is a function of protein intake. Growth, pregnancy and any protein
anabolism relate with riboflavin intake. An adequate allowance is 0.0025 mg riboflavin per gram
of protein intake. However, the FAO/WHO Expert Group and several Asian countries, including
the Philippines, express riboflavin requirement in terms of caloric intake.

The present RENI is 1.3 mg/day for young adults and older men and 1.1 mg/day for young
adults and older women. The 2002 RENI for riboflavin is as follows:

Adult Men, 19 years & over 1.3 mg/day

Adult Women, 19 years & over 1.1 mg/day
Pregnant 1.7 mg/day
Breast feeding 1.7 mg/day
Adolescents See RENI Appendix
B.

Deficiency and Toxicity

Riboflavin deficiency most often occurs in combination with a deficiency of other B vitamins.
Symptoms include an inflamed mouth with cracks in the corners (cheilosis), scaly, dry facial
skin, confusion, and poor wound healing. Rapidly growing tissues such as skin and mucous
membranes lining the eyes, mouth, tongue are first to be affected. The tongue becomes
magenta red and swollen (glossitis).

Riboflavin toxicity is not a problem because of limited intestinal absorption.

Food Sources and Cooking/Processing Stability

The best food sources for riboflavin are organ meats (liver, kidney, heart), shellfish (oysters,
clams), milk, yogurt and cheeses, meats, poultry (especially the dark meat), eggs (in the yolk),
enriched breads, fortified breakfast cereals, and dark green vegetables like leafy greens,
broccoli, and green peppers, and seaweed. Good sources are soy beans, peanuts, almonds;
legumes like green munggo, patani or lima beans, and sweet potatoes.

Riboflavin is processed out of whole grain when it is milled into flour and out of rice when it is
polished. It is restored to white wheat flour and cornmeal through “enrichment”; therefore,
products made from enriched flour provide a good source of riboflavin. In other countries (e.g.,
USA), riboflavin is required in enriching flours and cereals.

Guidelines in Cooking/Processing. Riboflavin is light sensitive, however. Ever wondered

why milk is seldom sold in clear glass bottles? Fifty percent of the riboflavin in a clear bottle is
destroyed in 2 hours if exposed to direct sunlight, and approximately 20% is destroyed on an
overcast day. With modern packaging of liquid milk in cartons or cans, loss from sunlight is no
longer a problem.

Light and alkalis will inactivate riboflavin in foods, but acids, air, and heat do not affect it.
Riboflavin is water-soluble and fairly heat-stable. Small amounts of riboflavin will leach into
cooking water because it is water-soluble, but if the cooking water is used, there should be
fairly complete retention.

Conserve riboflavin by cooking foods in small amounts of water and by using any drippings or
liquids. Steaming and microwaving are preferred to boiling and simmering in water.

4.4.4. Niacin (Vitamin B3, Nicotinic Acid, Nicotinamide, and Niacinamide)

The two forms of niacin that are biologically active are niacin and nicotinic acid or its –amide
form, nicotinamide or niacinamide. The historical and obsolete name is antipellagra factor or
PPF (pellagra-preventive factor) because niacin prevents and cures the deficiency disease
pellagra.

Niacin is absorbed in the intestinal tract, and any excess is eliminated by the kidneys. Little is
stored in the body; hence an adequate intake of niacin from food sources should be eaten daily.
Niacin is found in the tissues largely as part of the coenzymes NAD or coenzyme I and NADP or
coenzyme II.

Niacin Functions

Niacin is central to the release of energy from foods, and helps maintain healthy skin, nerves,
and digestive tract.

Niacin is essential to almost every biochemical link in the metabolism of carbohydrates,

proteins, and fats for energy. If there is a shortfall, the energy reactions are blocked. As a
result, the amount of niacin needed is generally proportional to the calories eaten.

Niacin is a constituent of two important co-enzymes, which assist in the breakdown of sugar to
release energy, in fat synthesis, and in tissue respiration. This essential vitamin helps keep the
skin, mouth, tongue, and digestive tract in healthy condition. It has a role in the proper
functioning of the nervous system.

Niacin protects the skin, nervous tissues, and the digestive tract from disorders. It also aids in
calcium mobilization and is required in DNA repair.
Large doses of niacin have been shown to lower blood cholesterol levels, lower blood
triglycerides and lower the low-density lipoproteins (LDLs), while raising HDLs ( the good
cholesterol).

Therapeutic use of niacin should be conducted under a doctor’s supervision, because at high
dosages niacin is no longer acting as a vitamin but is considered a drug. Read the effects of
megadoses of niacin under HIGHLIGHTS.

Measurement and Recommended Intake

There are several forms of niacin, and niacin reported in food composition tables represents the
niacin already available in foods. However, there is also a precursor – the amino acid
tryptophan. About 60 mg can be converted to 1 mg of niacin.

The recommendations assume sources of niacin from both preformed niacin and the amount
that can be converted from tryptophan. The combined measure is called niacin equivalents
(NEs). Studies with human requirements indicated a minimum level of 4.4 mg/1000 kcal. Age,
growth, body size, illness, lactation, surgery and increased physical activity, which are all
functions of energy requirement, also increase niacin needs.

Niacin allowance for Filipino adults ranges from 14 to 18 mg niacin equivalent (mg NE) per
day.

The Philippine RENI (see Appendix B) for niacin measured as mg NE/day, are as follows:

Males (13 yrs. & over) =16 Infants, 6 to 11 mos. =4

Females (13 yrs. & over) =14 Children, 1 to 9 yrs. =6-9
Pregnant women = plus 4 or 18 Children, 10 to 12 yrs.=12
Lactating women = plus 3 or 17

Additional niacin intake may be required for persons on dialysis, those with malabsorption
syndrome, pregnant women bearing multiple fetuses, women breast feeding more than one
infant, alcoholics and drug addicts.

Deficiency and Toxicity

Early stages of niacin deficiencies include symptoms such as fatigue, decreased appetite,
indigestion, diarrhea, nervous irritability, and sometimes a swollen, red sore tongue (glossitis).
Pigmented rashes may develop symmetrically in areas of the skin exposed to sunlight known as
symmetrical dermatitis.

Prolonged niacin deficiency results in mental symptoms that include irritability, headaches, and
loss of memory, emotional instability, psychosis and delirium. Children with a niacin deficiency
can be weak and show poor growth and development.

Symptoms of a severe deficiency include skin and gastrointestinal lesions, inflammation of the
mucous membranes, and mental disorders leading to dementia and death. This condition is
called pellagra and is sometimes described with its classical 4 Ds: dermatitis, diarrhea, dementia
and finally death. Clinical pellagra may also represent the combined deficiency of niacin and
riboflavin.

Toxic effects have been observed at prolonged, very high niacin intakes of the nicotinic acid
form. The first noticed side effect is usually flushing; the intakes can be readily adjusted to a
lower amount. Flushing is the result of a release of histamine and can cause reddening of the
face, arms, and chest and a burning, tingling, or itching sensation in the hands and feet.
Adverse effects of niacin toxicity occur faster for those who have a liver dysfunction or a history
of liver disease, diabetes, active peptic ulcer disease, gout, cardiac arrhythmia, migraine
headaches, alcoholism, or inflammatory bowel disease.

Other reported symptoms of toxicity from niacin include nausea, diarrhea, high blood uric acid
levels, high blood sugar, and heart arrhythmia. The nicotinamide form does not cause these
toxic effects, but it also does not reduce blood lipid levels.

Food Sources and Cooking/Processing Stability

The best niacin sources are organ meats such as liver, fish, poultry, peanuts, beef, lamb, goat,
veal, lean pork and ham, peanut butter, enriched rice and breads, fortified breakfast cereals,
tofu or tokwa and other soybean products, enriched pasta, almonds, shrimp, sunflower seeds,
soybeans, potatoes, mushrooms, tomato sauces, sweet potatoes, green peas, corn, and
munggo. See Figure 4.5.

Other foods are good sources when the availability of the niacin precursor tryptophan is
considered. Milk products, legumes, more vegetables, and some fruits also become excellent
sources. IN rank order, they are cheeses (most of them), tokwa and soymilk, cooked dried
beans, green peas, mangos, corn, yogurt, eggs, dark green vegetables, broccoli, prune juice,
orange juice, raisins, and berries.

Niacin in meats is in different form and appears to be more available. Niacin in cooked mature
beans, liver, and in fortified foods in the free form is highly available.

Guidelines in cooking and processing to retain niacin in foods:

 Niacin is the most stable of the B-vitamins. It is fairly stable in food preparation and
storage; however, as a water-soluble vitamin, some will dissolve into cooking liquid. If
the liquid is retained and consumed, losses are minimized.
 Avoid washing enriched rice or save the rice washings (hugas-bigas) and use as a stock
or broth starter.
 Prolonged treatment with the drug Isoniazid will reduce the conversion of tryptophan to
niacin, but will not interfere with preformed niacin.

4.4.5. Vitamin B6 (Pyridoxal, Pyridoxol, Pyridoxamine, and Pyridoxal Phosphate)

Pyridoxine is the group name for vitamin B 6, which includes: pyridoxal (an aldehyde from),
pyridoxol (an alcohol form), and pyridoxamine (anamine form).
Pyridoxine is easily absorbed in the intestines and is circulated in the blood as the active
coenzyme, pyridoxal phosphate. Storage in the liver and muscle tissues are limited, hence this
vitamin must be supplied in the daily diet adequately for its multiple functions described in the
next sections.

Vitamin B6 Functions

Vitamin B6 is a vital part in more than 100 enzymes and coenzymes involved in amino acid and
glycogen metabolism. It is necessary for brain function and formation of red blood cells, help
convert tryptophan to niacin, is involved in the immune function and steroid hormone activity,
and reduces risk of atherosclerosis.

If there is an increase in protein in the diet, the need for B 6 increases to convert extra protein
into energy. It also releases energy by converting body stores of glycogen into glucose.

Vitamin B6 is required for building some amino acids and for converting others to hormones,
e.g., in the synthesis of niacin from tryptophan.

It is necessary in the production of red blood cells and white blood cells, and the proper
functioning of nerve tissues.

It is also involved with the metabolism of polyunsaturated fats.

Vitamin B6 has been reported as a useful treatment for carpal tunnel syndrome, in which
pressure on the nerves of the hands causes weakness and pain.

Short-term supplemental doses of vitamin B 6 are also used to treat PMS (premenstrual
syndrome), depression, and muscular fatigue. However, the use of contraceptives reduces the
utilization of pyridoxine, thus increasing the need for the vitamin.

Measurement and Recommended Intake

Pyridoxine intake should parallel protein requirement as explained under Functions. Research
however, does not support claims that large doses of vitamin B 6 enhance muscle strength or
physical endurance.

The Philippine RENI (see Appendix B) for pyridoxine measured as mg/day are as follows:

Males (10-49 yrs.) 1.3 Infants, 6 to 11 mos. 0.3

Males (50 yrs. & over) 1.7 Children, 1 to 3 yrs. 0.9
Females (10-18 yrs.) 1.2 Children, 4 to 6 yrs. 1.0
Females (19-49 yrs.) 1.3 Pregnancy 19.0
Females (50 yrs. & over) 1.5 Lactation 20.0

Deficiency and Toxicity

Deficiencies rarely occur alone, and are most likely to be seen in people who are deficient in
several B-complex vitamins.
Vitamin B6 deficiency results in disorders of the eyes, skin, tongue and mouth. Later signs are
small-cell type anemia, insulin sensitivity, nervousness, and convulsions. Neurologic symptoms
can include weakness, tingling and pain in the hands and arms, depression, headaches,
confusion, and seizures. Deficiencies of vitamin B6 along with folate and vitamin B 12 can result
in elevated blood vessels of hemocysteine, which are associated with atherosclerosis and heart
disease.

Vitamin B6 is a water-soluble vitamin, but unlike other water-soluble vitamins, excesses

apparently are not completely excreted from the body. Toxicity cannot occur with food sources.
Toxicity can result from taking very large doses of supplements or from prescribed doses over
extended periods to treat pre-menstrual syndrome (PMS), carpal tunnel syndrome mental, or
other disorders. Reported consequences can vary from permanent nerve damage to reversal of
the symptoms when the overdoses are eliminated.

Food Sources and Cooking/Processing Stability

Vitamin B6 is available in large variety of unprocessed foods. Excellent sources are liver and
other glandular organs, poultry meat, fish and shellfish, nuts and seeds (especially hazelnuts
and sunflower seeds, peanuts and peanut butter), legumes (like munggo, black beans, soy
beans), whole grains, and bran cereals. See Figure 4.6.

Good sources include green leafy vegetables, tomatoes in various forms, squash, peppers,
potatoes, and many fruits like bananas, melons, and dried fruits. Fortunately, pyridoxine is
found in a wide variety of food sources. It is also found in cinnamon and cocoa.

Vitamin B6 from meats is more bioavailable than B6 from plant foods, although plant fiber does
not appear to affect absorption. In a mixed diet, approximately 75% is bioavailable.

Vitamin B6 is easily lost in cooking with water or liquid and prolonged heating. About 50 to 70%
can be lost in freezing fruits and vegetables and in processing luncheon meats. Processed and
refined foods often contain less than 50% of that found in the original unprocessed or
uncooked form, and exposure to sunlight (ultraviolet light) may reduce vitamin content even
more. Approximately 50 to 90% is lost in milling cereal grains. Currently, it is not added back
through enrichment.

4.4.6. Folate (Folacin, Folic Acid, and Pteroyl-monoglutamic Acid)

Folate is generally the term for all forms of this vitamin. The naturally occurring vitamin in food
is referred to as folate or folacin. The form used in fortification and vitamin supplements is
called folic acid (pteroyl-monoglutamic acid) and rarely occurs naturally in food. Its name
originated from the word “foliage” when it was first discovered to occur abundantly in fresh
green leafy vegetables.

Approximately 1/3 of folate is stored in the liver, and the rest is stored in body tissues.

Folate Functions
Folate is important in synthesis of DNA and RNA, new cell formation, protein metabolism, and
for normal growth. This function is especially important in tissues that have rapid cell
production and turnover, such as the bone marrow that produces blood cells, and the intestinal
tract where regeneration of some cells occurs every few days.

Folate is also required for the synthesis and breakdown the amino acids.

Adequate folate intake is essential before and during pregnancy for the growth of the fetus. A
deficiency can affect the nervous system and brain function. In the developing fetus, neural
tube defects, such as spina bifida and anencephaly may occur. Adequate intake reduces risk of
these birth defects.

Folate helps with normal formation of the red blood cells; deficiency signs include misshapen
red blood cells and anemia.

Folate, along with vitamins B 6 and B12, are protective against coronary heart disease and
atherosclerosis by reducing blood hemocysteine levels.

Higher intakes of folate are also associated with reduced incidence of colon cancer and cervical
cancer in women.

Measurement and Recommended Intake

Intakes for folate are measured in mcg of Dietary Folate Equivalents (DFE) or Folate Equivalent
(FE). This recognizes the different bioavailability of the folate used to enrich foods, which began
in 1998 in the U.S. Unfortunately analytical techniques for food can only measure total folate.
To date, no technique has been developed yet that can measure bioavailability. Therefore, food
data for folate will “understate” the actual (FE) available, especially if the person consumes
grain products fortified with folate in the United States and Canada.

In view of evidence linking folate intake with neural tube defects in the fetus, it is
recommended that all women capable of becoming pregnant consume 400 micrograms ((g) of
synthetic folic acid from fortified foods and/or supplements in addition to intake of food folate
from a varied diet.

The Philippine RENI is 400 µg DFE/day for older children (10-12 years), adolescents (13-18
years) and adults (19 years and above) while children 1-3 years need 160-300 µg DFE per day.
Growth, pregnancy, lactation, alcoholism and other stresses will need higher intake. The RENI
for pregnancy is 600 µg while that for lactation is 500 µg DFE.

Deficiency and Toxicity

Deficiencies can occur from alcohol abuse, poor food intake, and conditions that requires cell
production such as burns, blood loss, skin disease (measles, chicken fox), and pregnancies
especially those involving multiple births.

Those at risk of deficiency include pregnant women and premature infants, due to rapid cell
division and growth; the elderly, due to limited intake of high folate foods; alcoholics, because
alcohol inhibits folate absorption; and smokers, because smoke inactivates folate in the cells
lining the lungs.

Deficiencies of folate, vitamin B 6, and vitamin B12 can result in elevated blood homocysteine
levels, which can promote heart disease and atherosclerosis.

Homocysteine is an amino acid derived from the digestion of protein-rich foods. Normally,
several enzymes either turn homocysteine back into methionine (another amino acid), which
the body uses to build its own proteins, or they break it down for excretion in the urine. Folic
acid, vitamin B6 and vitamin B12 are necessary for metabolism of methionine. A number of genes
influence how the body uses folate, vitamins B 6 and B12, and can predispose a person to folate
deficiency, leading to high levels of homocysteine.

Other deficiency symptoms include poor growth, problems in nerve development and function,
diarrhea, inflammation of the tongue, mental conditions, and anemia. No adverse effects have
been observed associated with excess folate from foods. However, excessive intakes (from
supplements or fortified foods) may obscure and delay the diagnosis of vitamin B 12 deficiency.
This can result in risk of progressive unrecognized neurologic damage, in addition to pernicious
anemia.

Food Sources and Cooking/Processing Stability

Excellent food sources of folate are primarily found in liver, with, nuts, many dark green
vegetables, and many fruits, with lesser amounts in fish, eggs, and dairy foods. Except for
organ meats, meats are not rich sources.

Milk, green tea, and black tea have small amounts but if consumed in large quantities can
contribute to the dietary intake of folacin.

Natural folate is unstable and easily degraded by heat, oxidation, and sunlight, and as a result,
processing can drastically reduce folate content of foods.

It is estimated that 50 to 95% of the original folate in food can be lost in food preparation or
food processing. Normal household preparation can destroy as much as 50% in vegetables, and
re-heating destroys even more.

Food folate is approximately 50% bioavailable. Synthetic folate used in fortifying food is about
85% available when eaten as part of a meal. When taken as a supplement without any food,
folate is almost 100% available. Therefore, folic acid in fortified foods is about 1.7 times more
bioavailable than food folate.

4.4.7. Vitamin B12 (Cobalamin and Cyanocobalamin)

Vitamin B12 or cobalamin is a generic group of water-soluble vitamins with cobalt as an

important constituent; hence the chemical term is preferred by most biochemist and
nutritionists. There are several forms: cyanocobalamin, hydroxycobalamin, and
nitrosocobalamin. Cyanocobalamin is the most active biologically. However, the term vitamin B 12
still prevails because it identifies it as a member of the B-complex vitamins, hence it is the term
used here.

Vitamin B12 Functions

Vitamin B12 is necessary for development of red blood cells. It is needed - along with folacin –
where new cell growth is required and to help manufacture red blood cells. Because folacin and
vitamin B12 work together for cell formation and growth, a deficiency in one impairs the function
of the other. It plays an important role in building and maintaining the sheath that protects the
nerve fibers, hence is essential for the integrity of the nervous system.

Vitamin B12 is required for several enzymatic reactions to synthesize certain amino acids, and to
protect against atherosclerosis by functioning as a coenzyme for converting homocysteine to
other forms.

Measurement and Recommended Intake

Vitamin B12 is measured in milligrams (mg) or micrograms (mcg).

Because some older people may not be able to absorb B 12 normally, it is advised that those over
50 years of age should consume foods fortified with B 12 or take a B12 containing supplement,
which is more bioavailable.

Individuals who are unstable to absorb B 12 (caused by lack of the intrinsic factor) require
medical treatment. Strict vegetarians (or vegans) who eat no animal food may need
supplements.

The Philippine RENI for vitamin B12 in microgram per day (µg/day) is 2.4 µg for male and
female 10 years and over. For pregnancy and lactation, an additional 0.2 and 0.4 µg/day
(respectively). See Appendix B for details.

Deficiency and Toxicity

Vitamin B12 deficiencies are more likely triggered by inadequate absorption rather than
inadequate intake. The absorption of vitamin B 12 requires a factor in the stomach called the
intrinsic factor. It attaches to B12 and facilitates the absorption in the intestine. If this intrinsic
factor is lacking (such as in pernicious anemia, and often in the elderly), malabsorption of B 12
results.

A strict long-term vegetarian diet may induce a deficiency because B 12 is not found in plant
foods. Deficiencies in B12 and/or folacin can cause a form for anemia, and can result in an
increasing paralysis of the muscles and nerves due to degeneration of myelin sheath that coats
the nerves, spinal cord, and brain. Since the early symptoms are not detectable from a blood
clot, and early detection is necessary to prevent damage, this type of “sneaky” deficiency
damage has earned the name pernicious anemia.

Symptoms of deficiency may include those of anemia (paleness of skin, diminished energy,
shortness of breath, and palpitations) and neurologic defects (tingling and numbness of
extremities [worse in the lower limb], motor disturbances, gait abnormalities, loss of
concentration, memory loss, and disorientation).

Deficiency of vitamin B12 along with vitamin B6 and folate can result in elevated blood levels of
homocysteine, which can promote coronary heart disease and atherosclerosis. Gastritis, and
iron and vitamin B6 deficiencies will decrease absorption of vitamin B 12.

No toxic effects have been observed with B 12 intakes up to 100 mcg daily. When high doses are
given orally, the body compensates and smaller percentages of B 12 are eventually absorbed.

Food Sources and Cooking/Processing Stability

Naturally occurring vitamin B12 is found only in animal sources: meats, fish and shellfish, eggs,
and dairy products. For those who are strict vegetarians (vegans), fortified breakfast cereals
and other fortified with vitamin B 12 are good sources. There is no vitamin B 12 in plant foods,
although some might be produced by bacteria if a food has been fermented. Nutritional yeast
and beer, for example, have small amounts.

To ensure adequacy, supplemental vitamin B12 may be prescribed by the physician, especially
for the persons at risk to poor vitamin B 12 intake and utilization.
Vitamin B12 is generally fairly stable in food; however, there can be small losses in coking and
processing. Up to 10% is lost in milk during pasteurization. Another 30% can be destroyed by
boiling for several minutes, and about 50% can be lost if boiled for 10 minutes. Canned
evaporated milk contains only about 25% of the B 12 of the whole fluid milk.

4.4.8. Pantothenic Acid

Pantothenic acid comes from a Greek word that means “from everywhere”, because it is
widespread in nature and is present in all living cells. Obsolete names are chick anti-dermatitis
factor and filtrate factor.

For humans, pantothenic acid is an essential B-vitamin mainly because it is as component of

coenzyme A and participates in the metabolism of carbohydrate, fat, and protein.

Pantothenic Acid Functions

Pantothenic acid is vital for the synthesis and maintenance of coenzyme A, which involved the
production of energy from carbohydrates, protein and fats.

It is involved in over 100 different steps in the synthesis of neurotransmitters, steroid

hormones, and hemoglobin.

It helps in the metabolism of fatty acids and in the synthesis fatty acids, phospholipids,
cholesterol, acetylcholine, vitamin A, vitamin D, and steroid hormones and for the formation of
certain other nerve-regulating substances.

Measurement and Recommended Intake

Pantothenic acid is measured in milligrams (mg) or micrograms (mcg). The Philippine RENI
does not include pantothenic acid levels. The U.S has set an adequate intake (AI) level of 5
mg/day for adults.

It is believed that at least 4.0 to 7.0 mg a day is sufficient for an adult. Daily mixed diets may
contain as much as 15 mg, which is more than adequate.

Deficiency and Toxicity

Dietary deficiencies are not known because of its presence in a wide variety of foods. A mixed
diet is most likely to provide adequate supply for pantothenic acid daily.

Experimentally induced deficiencies can create weakness and fatigue, sleep disturbances,
reduced antibody production, muscle cramps, and reduced adrenal function.

Toxicity is not a problem with pantothenic acid, as no adverse effects have been observed.

Food Sources and Cooking/Processing Stability

Excellent food sources of pantothenic acid include liver, nuts, yogurt, chicken and turkey
(Especially the dark meat), fish and shellfish, eggs, lean pork and ham, legumes, vegetables
(especially mushrooms, tomatoes potatoes, peas, sweet potatoes), whole grain products and
whole oats. Citrus fruits and juices, bananas, melons and other fruits and vegetables are good
sources.

Pantothenic acid is severely reduced in the processed foods. Fresh, unprocessed foods are best.
Whole-wheat pasta and breads have twice the vitamin of white pasta and breads, for example.
Milling destroys at least half the pantothenic acid in grains, and it is not replaced by enrichment.

Pantothnic acid is readily destroyed by heat, and canned and frozen fruits and vegetables show
average losses of 50% or more from the fresh or raw form.

4.4.9. Biotin

Biotin is a sulfur-containing B-complex vitamin. It used to be called anti-egg white injury factor
because it was first observed in rats that showed deficiency symptoms when rats were fed
experimentally with large amounts of raw egg whites. The amount ingested was not possible
with humans. True biotin deficiency has not even been observed because it is occurs widely in
both plant and animal foods. It is synthesized in the intestines by microorganisms.

Biotin Functions

Biotin is an integral part of coenzymes involved in reactions that depend on bicarbonate or

carbon dioxide fixation necessary in metabolizing protein, carbohydrates, and fats into energy.
It is needed to synthesize glycogen and certain fatty acids, as well as the breaking down of
certain fatty acids and protein to produce energy.
Thus, the enzyme system biotin participates in, are both anabolic and catabolic, reactions. The
fixation of carbon dioxide aided by biotin into chemical energy without radiant energy is
sometimes called “dark reaction photosynthesis.”

Measurement and Recommended Intake

Biotin is measured in micrograms (mcg) only. Very minute amounts are needed, hence has
been called sometimes as “the micro-micronutrient.”

The Philippine RDA does not include biotin levels. The U.S. adequate intake (AI) level is 30
mcg/day for adults.

Deficiency and Toxicity

Biotin is water-soluble, and what the body does not need is excreted in the urine. Deficiencies
can occur with the use of certain anticonvulsants, and for individuals with malabsorption
syndrome. Deficiency symptoms include thinning of hair, sometimes loss of hair color, nausea,
rashes, depression, lethargy, hallucinations and other neurologic symptoms, like the tingling in
extremities.

Raw egg white contain a substance (avidin) that binds biotin and prevents absorption. This
effect does not occur with cooked egg whites.

Toxicity is not a problem because of the limited intestinal absorption of biotin. There is
insufficient data on which to base an upper limit for biotin. Toxicity has not been reported in
patients treated for biotin deficiency with daily doses up to 200 mg orally up to 30 mg
intravenously.

Food Sources and Cooking/Processing Stability

Excellent food sources of biotin are liver and other glandular organs, meats, cooked egg yolks
or whole eggs, milk and cheese. Good sources are fish, nuts, legumes, sweet potatoes, green
leafy vegetables, and bananas. All other whole grains, fruits and vegetables contain some
biotin.

The uptake of biotin by the body varies in foods; however, people who consume a variety of
foods will obtain sufficient biotin in their diet. It is more stable during cooking and processing
compared to other B-vitamins.

4.4.10. Choline

Choline is a constituent of many substances in the body that are essential for the structural
integrity of cell membranes. Undoubtedly, it is essential to life. The demand for choline is also
interdependent on the presence of folic acid, vitamin B 12, pyridoxine, and methionine (an amino
acid). With such close relationships, it is difficult to measure needs for choline without
considering the other nutrients.

Choline Functions
Choline is the last B-vitamin to be added as an essential nutrient for humans. Its main function
is for the metabolism of the methyl- radical (mehylation reactions) that is important in
cholinergenic neurotransmissions, lipid and cholesterol transport, and in the production of
acetylcholine and phospholipids.

Choline accelerates the production and release of acetylcholine and is therefore involved in
memory storage, muscle control, and many other functions.

As a precursor for the synthesis of phospholipids, it is important for the structure and function
of membranes, intracellular message, export of very low-density lipoproteins, and a platelet-
activating factor.

Choline is a precursor for betaine, which is required for kidney function and other body
processes.

Mesurement and Recommended Intake

Choline is measured in milligrams (mg). The Philippine RENI does not include choline levels.
The U.S. allows an adequate intake (AI) level of 550 mg/day for adult men and 425 mg/day for
adult women. The tolerable upper level (UL) in the USA for adults is 3.5 grams (3,500 mg) per
day.

The recommended amounts may be influenced by the availability of methionine, folate, and
vitamin B12 in the diet.

Deficiency and Toxicity

Choline deficiency in humans has not been observed, but in experimental animals, fatty liver,
cirrhosis and hemorrhagic degeneration of the kidneys, lungs, heart and adrenals were the
main signs of choline deficiency.

High doses of choline have been associated with fishy body odor, vomiting, salivation,
hypotension, sweating and gastrointestinal effects

A pharmacologic dose of choline seemed to alleviate symptoms of Huntington’s disease and

tardive dyskinesia.

Food Sources

Choline is widely distributed in foods. Especially rich sources include milk, liver, cauliflower,
iceberg lettuce, and peanuts. Lecithin added during food processing may also contribute added
amounts.

4.5. Highlights
It has been pointed out in previous discussions that toxic effects of excessive intake for water-
soluble vitamins are not serious as those for fat-soluble vitamins. However, there have been
clinical observations when megadoses of some water-soluble vitamins are quite deleterious, as
summarized below:

Vitamin C 1,000 mg or higher may cause upset stomach, diarrhea, or constipation.

Niacin Megadoses are sometimes prescribed to lower cholesterol levels. However, some
patients have side effects from doses higher than the RDA. It could raise the production of liver
enzymes and blood levels of sugar and uric acid, leading to liver damage and an increased risk
of diabetes and gout.

Vitamin B6 Continued use of 50 mg or more a day may damage nerve in arms, legs, hands
and feet. Some experts say the damage is likely to be temporary; other say that it may be
permanent.

Choline Very high doses (14 to 37 times the adequate amount) have been linked to
vomiting, salivation, sweating, low blood pressure and fishy body odor.

4.6. Highlights

After reading this chapter, do you agree that vitamins deserve to be called the “miracle
workers?”

Most water-soluble vitamins are generally found in the same groups of foods, namely whole
grains, leafy vegetables, legumes, meat and dairy products. Food sources of vitamin C (ascorbic
acid) are fresh fruit (and especially citrus fruit) and vegetables. Vitamin B 12 is synthesized by
micro-organisms and then becomes incorporated in animal tissues. This is why vegans, who
avoid animal products altogether, are at risk of developing B 12 deficiency.

As for the food sources of fat-soluble vitamins, they generally include leafy vegetables, seed
oils, meat and full-fat dairy products. More specifically, as far as vitamin A is concerned, it
should be noted that the term includes both retinol and provitamin A carotenoids. Liver, fortified
margarine and full-fat milk products are good dietary sources of retinol and bright orange fruits
and vegetables (e.g. carrots, pumpkins, sweet potatoes, ripe mangoes) and dark-green leafy
vegetables (e.g. peppers, spinach, broccoli, malunggay) are the best sources of carotenes.

The dietary sources of vitamin D, which are not as important as its endogenous synthesis on
the skin by the sunlight, however, are oily fish, eggs, liver, full-fat dairy products and fortified
milk. Oily fish and green leafy vegetables are also rich in vitamin E. Other good sources of
vitamin E are seeds, as well as nut oils and seed oils.

Of current interest are findings about vitamins as phytochemicals. Phyto is the Greek word
for plants; a phytochemical is simply a chemical form plants and the term is applicable to
vitamins. Colors such as beta-carotene, a deep yellow pigment in fruits and vegetables that
your body can convert to a form of vitamin A, is a phytochemical. Vitamins that act as
antioxidants, as described previously, ae phytochemicals.
Also, there are phytoestrogens, hormone-like chemicals, which are still undergoing further
research. A recent study supports that a diet high in phytoestrogens, such as the isoflavones
found in soybeans, may lower the risk of heart disease and reduce the incidence of
reproductive cancers (cancers of the breast, ovary, uterus and prostate. This topic of
phytochemicals and phytoestrogens need more studies establish nutritional facts.