Vitamins are organic compounds necessary in small doses for good health. They are also very useful for energy, growth and for various physiological processes.
Scientists first discovered very small amounts of essential substances in 1914. They felt that these essential substances belonged to a chemical group known as "amines". Since they also felt that they were vital to health, they called them "vital-amines" or, for short, "vitamines". Soon further examination proved them different to the amine group, and the "e" was dropped from the end, making them "vitamins".
At first only three vitamins were known, A, B, and C. Subsequently many more were found. Some vitamins are fat-soluble and some water-soluble. The fat-soluble vitamins like A and D can be stored more easily in the body than the water-soluble group.
Taking a normal diet usually provides all the necessary vitamins. However, under periods of stress, after recovering from serious sickness or even after a rigorous course of dieting, deficiency is frequent. Vitamin deficiencecies are found more often in children and infants.
Vitamin A (retinal)
This is the most important vitamin as far as the eyes are concerned. Vitamin A is carried in the blood plasma so as to be immediately available to the eye when required.
Which foods are rich in Vitamin A? From which foods can the body directly absorb vitamin A and from which foods does it have to make it indirectly?
Absorption of vitamin A takes place directly from:
(a) Fat of fish liver. Cod liver oil and halibut liver oil have the highest proportion.
(b) Egg, milk.
Vitamin A is indirectly absorbed as a substance called carotene which is converted to vitamin A in the liver. It is present in:
(a) Carrots, spinach leaves, green vegetables.
(b) Orange and yellow fruits.
However, it must be remembered that when the indirect mode is used larger, quantities of the food have to be ingested to provide adequate vitamin A. In deficiency states, the indirect forms are usually not sufficient to provide enough vitamin A to serve any purpose.
Copyright 2009
Healthguidance.org. All rights reserved.
E-mail. DISCLAIMER: By printing,
downloading, or using you agree to our full terms. Review the full terms at
the following URL:
http://www.healthguidance.org/pages/Terms-of-Service. If you do not agree to the
full terms, do not use the information. We are only publishers of this
material, not authors. Information may have errors or be outdated. The
information on this website is not intended to replace a one-on-one
relationship with a qualified health care professional and is not intended as
medical advice. Statements made pertaining to the properties or functions of
nutritional supplements have not been evaluated by the Food and Drug
Administration. If you have a medical problem or symptoms, consult your
physician. User assumes all risk of use, damage, or injury. You agree that we
have no liability for any damages. We are not liable for any consequential,
incidental, indirect, or special damages. You indemnify us for claims caused
by you.
Advertisements
