Vitamin A: Vitamin A is retinol. Carotene compounds
(found, for example, in egg yolk, butter and cream) are gradually
converted by the body to vitamin A (retinol). A form of vitamin A
called retinal is responsible for transmitting light sensation in the
retina of the eye.
Deficiency of vitamin A leads to night
The word "vitamin" was coined in 1911 by the Warsaw-born
biochemist Casimir Funk (1884-1967). At the Lister Institute in
London, Funk isolated a substance that prevented nerve inflammation
(neuritis) in chickens raised on a diet deficient in that substance.
He named the substance "vitamine" because he believed it was
necessary to life and it was a chemical amine. The "e" at the end was
later removed when it was recognized that vitamins need not be
The letters (A, B, C and so on) were assigned to the vitamins in
the order of their discovery. The one exception
was vitamin K which was assigned its "K" from
"Koagulation" by the Danish researcher Henrik
Dam. The vitamins include:
- Beta carotene: An antioxidant which protects cells
against oxidation damage that can lead to cancer. Beta carotene is
converted, as needed, to vitamin A. Food sources of beta carotene
include vegetables such as carrots, sweet potatoes, spinach and other
leafy green vegetables; and fruit such as cantaloupes and apricots.
Excessive carotene in the diet can temporarily yellow the skin, a
condition called carotenemia, commonly seen in infants fed largely
- Vitamin B1: Thiamin, acts as a coenzyme in body
metabolism. Deficiency leads to beriberi, a disease of the heart and
- Vitamin B2: Riboflavin, essential for the reactions
of coenzymes. Deficiency causes inflammation of the lining of the
mouth and skin.
- Vitamin B3: Niacin, an essential part of coenzymes
of body metabolism. Deficiency causes inflammation of the skin,
vagina, rectum and mouth, as well as mental slowing.
- Vitamin B6: Pyridoxine, a cofactor for enzymes.
Deficiency leads to inflammation of the skin and mouth, nausea,
vomiting, dizziness , weakness and anemia.
- Folate (folic acid): Folic acid is an important
factor in nucleic acid synthesis (the genetic material). Folate
deficiency leads to megaloblastic anemia.
- Vitamin B12: An essential factor in nucleic acid
synthesis (the genetic material of all cells). Deficiency leads to
megaloblastic anemia, as can be seen in pernicious anemia.
- Vitamin C: Ascorbic acid, important in the synthesis
of collagen, the framework protein for tissues of the body.
Deficiency leads to scurvy, characterized by fragile capillaries,
poor wound healing, and bone deformity in children.
- Vitamin D: A steroid vitamin which promotes
absorption and metabolism of calcium and phosphorus. Under normal
conditions of sunlight exposure, no dietary supplementation is
necessary because sunlight promotes adequate vitamin D synthesis in
the skin. Deficiency can lead to osteomalcia in adults and bone
deformity (rickets) in children.
- Vitamin E: Deficiency can lead to anemia.
- Vitamin K: An essential factor in the formation of
blood clotting factors. Deficiency can lead to abnormal
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