Download Vitamins are organic substances that cannot be produced by the

REVIEW
MULTIVITAMINS
By
Ronelle van der Merwe (B.Pharm)
Amayeza Information Centre
Information on vitamins
Vitamins are organic substances that cannot be produced by the human body. The only way of getting all of the vitamins the
body needs is to ingest them, in small quantities, through the diet. Vitamins are essential for normal cell function, growth and
development. There are 13 essential vitamins, which the body needs to function. They can be divided into two groups, fatsoluble or water-soluble.
Fat-soluble vitamins include vitamins A,D,E and K. The body stores small amounts of these for use as needed. The water-soluble
vitamins are the B vitamins and vitamin C. These vitamins are easily absorbed by the body, which normally doesn't store large
amounts. The kidneys remove excess water-soluble vitamins ingested, which are excreted in the urine.
The recommended daily allowance (RDA) is the amount of each vitamin that the average person needs to remain healthy. A
person who consumes too little or too much of a certain vitamin is at risk of developing a nutritional disorder.
Although many of the vitamin deficiency diseases, such as rickets and scurvy, have been largely eliminated from developed
countries, many western diets are poor in nutritional value. There is currently great debate around whether or not vitamin
supplementation can prevent many of the diseases that plague western culture.
Similarly, ingesting too much of a certain vitamin can have negative consequences for a person’s health. When taken in daily
doses that are more than 10 times the recommended daily allowance, vitamins A and D are toxic but not vitamins E and K. Even
though high doses of vitamins E and K may not be toxic, they may still cause unpleasant side effects, for example, nausea and
headaches. High doses of the water-soluble vitamins, on the other hand, will simply be excreted from the body and
supplementation in excess of the RDA would simply be a waste.
Only two of the fat-soluble vitamins (A and E) are stored in the body to any extent. Depending on the body’s requirements,
vitamin C is stored in the smallest amounts and vitamin B12 in the largest amounts. It is estimated that it would require about
seven years to deplete the body’s reserves of vitamin B12.
Ensuring an adequate vitamin intake
To ensure sufficient vitamin intake it is important to consume a variety of nutrient-dense foods and beverages within the basic food
groups. At the same time, choose foods that limit the intake of saturated and trans-fats, cholesterol, added sugars, salt and
alcohol. Ideally, vitamins should be obtained in sufficient quantities from the diet. Vitamin needs should be met primarily
through consuming foods, with supplementation suggested for certain sensitive populations, such as:

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
People with certain health problems (e.g. people who are chronically ill, alcoholics)
People following a vegetarian or vegan diet
Women who are pregnant or breastfeeding
Whole foods are the best source of vitamins and minerals. Some of the benefits they offer over vitamin supplements are;

Greater nutrition. Whole foods usually contain a variety of the micronutrients the body needs. An
orange, for example, provides vitamin C but also beta carotene, calcium and other nutrients.

Essential fibre. Whole foods provide the essential fibre the body needs for effective digestion. It may
even help prevent certain diseases, for example diabetes and heart disease.

Protective substances. Whole foods also contain other substances recognised as essential for good
health. Fruits and vegetables, for example, contain phytochemicals. These are naturally occurring food
substances that may help protect against certain diseases for example cancer, diabetes and heart disease.
Whole foods are also sources of antioxidants – substances that slow down oxidation – a natural process
that leads to cell and tissue damage.
Table 1. Sources, needs and RDA’s of fat- and water-soluble vitamins
Vitamin
Principal source
Fat-soluble vitamins
Vitamin A
Liver, whole milk,
fortified dairy
products, eggs,
carrots,
dark leafy
vegetables, dark
yellow squashes,
sweet potato,
pumpkin
Vitamin D
Vitamin E
Vitamin K
Fortified dairy
products, egg yolks
Vegetable oil,
margarine, wheat
germ, nuts, green
leafy vegetables,
sunflower seeds
Green leafy
vegetables, broccoli,
brussels sprouts,
cabbage, lettuce,
soybean oil, canola
oil
Water-soluble vitamins
Vitamin B1
Enriched, fortified
(Thiamine)
or whole-grain
products, brewer's
yeast, organ meats,
pork, legumes,
seeds, nuts
Vitamin B2
Organ meats, dairy
(Riboflavin)
products, enriched
or fortified grain
products
Niacin
(Nicotinic acid)
Vitamin B6
(Pyridoxine)
Principal importance
Effects of deficiency
Effects of excess
RDA (SA
recomme
adults)



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

1000 mic

Normal vision
Healthy skin and
other surface tissues
Defence against
infections






Absorption of
calcium and
phosphorus from the
intestine
Bone mineralisation
Growth and repair

Antioxidant






Animal protein,

enriched, fortified or
whole-grain

products
Chicken, fish, pork, 
kidney, liver, bran,
potatoes and other

starchy vegetables,
Formation of blood
clotting factors
Normal blood clotting







Night blindness
Thickening of skin
around hair follicles
Drying of the whites
of the eyes and
cornea
Blindness
Spots on the whites
of the eyes
Risk of infection
Death
Abnormal bone
growth and repair
Rickets in children
Osteomalacia in
adults
Muscle spasms

Rupture of red blood
cells
Nerve damage

Bleeding












Headache
Peeling of the skin
Enlargement of the spleen and
kidneys
Bone thickening
Joint pains
Poor appetite
Nausea
Vomiting
Increased urination
Weakness
Nervousness
Thirst
Skin itching
Kidney failure
Calcium deposits throughout
the body
 Increase in vitamin K
requirement
5 microg
10 micro
65 micro
Carbohydrate
metabolism
Nerve and heart
function

Beriberi in infants
and adults, with
heart failure and
abnormal nerve and
brain function
1,4 mg
Carbohydrate
metabolism
Healthy mucous
membranes

Fissures and scaling
of the lips and
corners of the
mouth
Dermatitis
Pellagra
1,6 mg
Chemical reactions
in cells
Carbohydrate
metabolism
Amino acid and fatty
acid metabolism
Nervous system
function

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


Convulsions in
infants
Anaemias
Nerve and skin
18 mg
2 mg
non-citrus fruits,
disorders

Healthy skin
highly fortified
cereals
Biotin
Kidney, liver, milk,
 Carbohydrate and

Inflammation of the
egg yolk, fresh
fatty acid
skin and lips
vegetables, rolled
metabolism
oats
Vitamin B12
Animal and dairy

Maturation of red

Anaemias
(Cobalamin)
products, liver,
blood cells

Some psychiatric
beef, shellfish,

Nerve function
disorders
fortified ready-to
DNA synthesis

Poor vision
eat
cereals
Folic acid
Liver, yeast,

Maturation of red

Decrease in number
legumes, green leafy
blood cells,
and type of blood
vegetables, orange
cells

DNA and RNA
juice, fortified
synthesis
ready-to-eat cereals,
pasta, flour, bread
Pantothenic acid
Animal products,

Carbohydrate and fat 
Neurologic disease
whole-grain cereals,
metabolism

Burning feet
legumes
Vitamin C
Green and red

Bone and connective

Scurvy (bleeding
peppers, broccoli,
tissue growth
loose teeth,
spinach, tomatoes,
inflammation of the

Wound repair
potatoes,
gums)

Function of blood
strawberries, citrus
vessels
fruit, guavas

Antioxidants
1. RE = Retinol Equivalent
2. One RE = 1 microgram of retinol = 3.33 IU of vitamin A activity = 6 micrograms of beta-carotene.
3. Vitamin D is expressed as cholecalciferol. One microgram of cholecalciferol = 40 IU of vitamin D.
4. Alpha-TE = alpha-tocopherol equivalent.
5. One alpha –TE = 1 mg of d-alpha-tocopherol=1.49 IU of vitamin E activity. 1 IU=1 mg of dl-alpha-tocopheryl acetate.
In summary
Vitamins are important for the normal functioning of the body. The best source of vitamins is a balanced diet. It is important to
remember that multivitamin supplements are not a substitute for a healthy diet. Where vitamin supplementation is concerned it is
simply not a case of “if some is good, a lot is better.” High doses of certain vitamins can be toxic. The best way to get all of the
vitamins and other nutrients the body needs is through ingesting a variety of nutrient dense foods and beverages.
References
1. Up to Date. Version 15.3, 2008.
2. Micromedex Healthcare Series. 2007. Thomson Micromedex, Greenwood Village, Colorado.
3. http://www.fda.gov/consumer/updates/vitamins
4. http://www.mayoclinic.com/print/supplements
5. http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/vitamins
6. Berkow R. The Merck Manual of Medical Information. Home Edition. 1997. USA: Merck & Co, Inc.
100 micr
1 microg
200 micr
6 microg
60mg