Function Of Fat-Soluble Vitamins
Vitamin are essential.
Vitamins, although they are
required in minute amounts, are essential for growth
and reproduction; formation of antibodies;
coagulation of the blood; resistance to infection;
formation of intercellular substances; and integrity
of bones, teeth, skin, blood, and nervous tissue.
They also function as coenzymes for innumerable
chemical reactions concerned with the metabolism of
food, on which the nutrition of the body depends.
Fat-soluble vitamins and their functions.
The fat-soluble vitamins are A, D, E, and K. They are
called fat-soluble because they dissolve in fats and
excesses are stored in fatty tissues.
Vitamin A is particularly important for normal
growth, normal vision in dim light, healthy skin,
and it also helps keep the inner linings of the body
(epithelial tissue) healthy and resistant to
infection. True vitamin A is found only in foods of
animal origin, such as liver, eggs and butter.
Provitamin-A or carotene, which can be converted to
true vitamin A by the body, is found in dark green
and yellow vegetables and fruits, such as spinach,
winter squash, peaches, and cantaloupe. Vitamin A is
one of the nutrients most commonly lacking in the
average diet.Vitamin D
is important for bone development and is essential
for the utilization of calcium.
It is called the "sunshine vitamin" because it can
be formed in the skin by the action of sunlight.
Few foods contain much vitamin D. Best sources are
sardines, salmon, herring, and tuna. However, milk
and margarine are commonly fortified with Vitamin D.Vitamin E
is an antioxidant, which means that it prevents
rancidity caused by oxidation. It offers protection
to the red blood cells in the presence of blood
destroying agents and protects vegetables, whole
grain foods, and vegetable oils, contain small
amounts of vitamin E. To characterize the vitamin,
the word "Tocopherol" was coined. While at least
four tocopherols have been isolated and named Alpha,
Beta, Gamma, and Delta, Alpha is the most potent and
is considered synonymous with vitamin E. Natural
vitamin E, which is extracted from soya bean oil, Is
designated D-Alpha, while synthetic vitamin E is
designated DL-Alpha.Vitamin K
is a blood clotting factor. In fact, it was
originally named Koagulations-vitamin, which was
later shortened to vitamin K. The best sources are
alfalfa and other green leafy materials.
Since vitamin K can be synthesized by intestinal
flora, supplementation is rarely needed. Thus,
vitamin K is rarely included in dietary supplements.