Organic compound required in small amounts in the diet to maintain normal metabolic functions.
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| Vitamin foods |
The term vitamine (1911) was changed to vitamin when it was realized that not all vitamins are amines (i.e., not all contain nitrogen).
Many vitamins act as or are converted to coenzymes. They neither provide energy nor are incorporated into tissues.
Water-soluble vitamins (vitamin B complex, vitamin C) are excreted quickly.
Fat-soluble vitamins (vitamin A, vitamin D, vitamin E, and vitamin K) require bile salts for absorption and are stored in the body.
The normal functions of many vitamins are known.
Deficiency of specific vitamins can lead to diseases (including beriberi, neural tube defect, pernicious anemia, rickets, and scurvy).
Excess amounts, especially of fat-soluble vitamins, can also be dangerous:
e.g., too much vitamin A causes liver damage, an effect not seen with beta-carotene, which the body converts into vitamin A.
Several vitamins are now known to support the immune system. Most vitamins are adequately supplied by a balanced diet, but people with higher requirements may need supplements.
Vitamin A also called Retinol
Fat-soluble alcohol, most abundant in fatty fish and especially in fish-liver oils.
It is not found in plants, but many vegetables and fruits contain beta-carotene (see carotene), which is readily converted in the body to vitamin A.
It functions directly in vision, especially night vision.
A derivative, retinaldehyde, is a component of the visual pigments, including rhodopsin, in the retina. Humans require vitamin A in very small amounts.
Unlike carotenes, it is toxic in large amounts and is readily destroyed by exposure to heat, light, or air.
Vitamin B complex
Water-soluble organic compounds with loosely similar properties, distribution in natural sources, and physiological functions.
Most are coenzymes, and all appear essential to the metabolic processes of all animal life.
They include thiamin (B1), Riboflavin (B2), niacin, vitamin B6, pantothenic acid, folic acid, biotin, and vitamin B12 (cobalamin);
some authorities also include choline, carnitine, lipoic acid, inositol, and para-aminobenzoic acid.
Vitamin B6 is needed for metabolism of amino acids and prevention of skin and nerve disorders.
Vitamin B12 prevents pernicious anemia and is involved in nucleic-acid synthesis, fat metabolism, and conversion of carbohydrate to fat.
The B complex vitamins are particularly abundant in cereal grains, meats, nuts, and some fruits and vegetables.
Thiamin or vitamin B1
Organic compound, part of the vitamin B complex, necessary in carbohydrate metabolism.
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| vitamin B1 |
It carries out these functions in its active form, as a component of the coenzyme thiamin pyrophosphate.
Its molecular structure includes a substituted pyridine ring and a thiazole ring.
Thiamin is found most abundantly in whole cereal grains and certain other seeds. Deficiency leads to beriberi.
Riboflavin or vitamin B2
Yellow, water-soluble organic compound, abundant in whey and egg white.
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Vitamin B2 |
It has a complex structure incorporating three rings.
Green plants and most microorganisms can synthesize it; animals need to acquire it in their diet.
It exists in combined forms as coenzymes and functions in the metabolism of carbohydrates and amino acids.
A syndrome resembling pellagra is thought to result from riboflavin deficiency. See also flavin.
Niacin or nicotinic acid vitamin B3
Water-soluble vitamin of the vitamin B complex, essential to growth and health in animals, including humans.
It is found in the body only in combined form as a coenzyme, nicotinamide adenine dinucleotide (NAD), which is involved in the metabolism of carbohydrates and the oxidation of sugar derivatives and other substances.
One of the most stable vitamins, it survives most cooking and most preserving processes.
It is widely found in dietary sources, especially lean meat.
Deficiency causes pellagra. It is used as a drug to reduce high cholesterol levels in the blood.
Vitamin B12-Cynocobalamin
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| Vitamin B12 |
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins. It is normally involved in the metabolism of every cell of the human body, especially affecting DNA synthesis and regulation, but also fatty acid synthesis and energy production. As the largest and most structurally complicated vitamin, it can be produced industrially only through bacterial fermentation-synthesis.
Vitamin B12 consists of a class of chemically-related compounds (vitamers), all of which have vitamin activity. It contains the biochemically rare element cobalt. Biosynthesis of the basic structure of the vitamin in nature is only accomplished by simple organisms such as some bacteria and algae, but conversion between different forms of the vitamin can be accomplished in the human body. A common synthetic form of the vitamin, cyanocobalamin, does not occur in nature, but is used in many pharmaceuticals and supplements, and as a food additive, because of its stability and lower cost. In the body it is converted to the physiological forms, methylcobalamin and adenosylcobalamin, leaving behind the cyanide, albeit in minimal concentration. More recently, hydroxocobalamin (a form produced by bacteria), methylcobalamin, and adenosylcobalamin can also be found in more expensive pharmacological products and food supplements. The extra utility of these is currently debated.
Vitamin B12 was discovered from its relationship to the disease pernicious anemia, which is an autoimmune disease in which parietal cells of the stomach responsible for secreting intrinsic factor are destroyed. Intrinsic factor is crucial for the normal absorption of B12, so a lack of intrinsic factor, as seen in pernicious anemia, causes a vitamin B12 deficiency. Many other subtler kinds of vitamin B12 deficiency and their biochemical effects have since been elucidated.
Biotin-vitamin B7
Biotin is a water-soluble B-complex vitamin (vitamin B7) discovered by Bateman in 1916[chronology citation needed]. It is composed of a ureido (tetrahydroimidizalone) ring fused with a tetrahydrothiophene ring.
A valeric acid substituent is attached to one of the carbon atoms of the tetrahydrothiophene ring. Biotin is a coenzyme in the metabolism of fatty acids and leucine, and it plays a role in gluconeogenesis.Organic compound, part of the vitamin B complex, essential for growth and well-being in animals and some microorganisms.
A carboxylic acid with two rings in its structure, it includes nitrogen and sulfur atoms as well as carbon, hydrogen, and oxygen. It functions in the formation and metabolism of fats and carbohydrates.
It is widely distributed in nature and is especially abundant in egg yolk, beef liver, and yeast.
A biotin deficiency can be induced by consuming large amounts of raw egg white, which contains a protein (avidin) that combines with biotin and makes it unavailable. Biotin is needed to synthesize fatty acids and convert amino acids to glucose in the body.
Folic acid or folate-Vitamin B9
Folic acid (also known as vitamin B9, vitamin Bc or (folacin) and folate (the naturally occurring form), as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acidare forms of the water-soluble vitamin B9.
Folic acid is itself not biologically active, but its biological importance is due to tetrahydrofolate and other derivatives after its conversion to dihydrofolic acid in the liver.
Vitamin B9 (folic acid and folate inclusive) is essential to numerous bodily functions.
The human body needs folate to synthesize DNA, repair DNA, and methylate DNA as well as to act as a cofactor in biological reactions involving folate.
It is especially important in aiding rapid cell division and growth, such as in infancy and pregnancy. Children and adults both require folic acid to produce healthy red blood cells and prevent anemia.
Folate and folic acid derive their names from the Latin word folium (which means "leaf"). Leafy vegetables are a principal source, although in Western diets fortified cereals and bread may be a larger dietary source.
Vitamin C or ascorbic acid
Water-soluble organic compound important in animal metabolism.
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| Orange and Citrus Fruits |
Most animals produce it in their bodies, but humans, other primates, and guinea pigs need it in the diet to prevent scurvy.
It is essential in collagen synthesis, wound healing, blood-vessel maintenance, and immunity.
Some studies have found a moderate benefit of vitamin C in reducing the duration and severity of the common cold.
It works as an antioxidant in the body and is used as a preservative. It is easily destroyed by oxygen.
Excellent sources are citrus fruits and fresh vegetables.
Vitamin D -Cholecalciferol
Any of a group of fat-soluble alcohols important in calcium metabolism in animals to form strong bones and teeth and prevent rickets and osteoporosis.
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It is formed by ultraviolet radiation (sunlight) of sterols (see steroid) present in the skin.
The most important of these sterols are 7-dehydrocholesterol, formed by metabolic processes in animals, and ergosterol, present in vegetable oils.
The action of sunlight on the skin converts these two compounds, respectively, to cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2).
Vitamin D is added to margarine, milk, and cereals for the benefit of those who may not get enough sunlight in winter.
As little as 5 micrograms each day appear adequate for children. Because the body cannot excrete it, prolonged high intake can cause a toxic reaction including fatigue, nausea, and abnormal calcium accumulation.
Vitamin E or Tocopherol
Fat-soluble organic compound found principally in certain plant oils and leaves of green vegetables.
Vitamin E acts as an antioxidant in body tissues and may prolong life by slowing oxidative destruction of membranes.
Certain rodents require it for normal reproduction. Besides uses in foods and in nutritional research and supplements,
it is used to retard rancidity in fats, especially vegetable oils.
Vitamin K -phylloquinone
Any of several fat-soluble compounds essential for the clotting of blood.
A deficiency of vitamin K in the body leads to an increase in clotting time.
In 1929 a previously unrecognized fat-soluble substance present in green leafy vegetables was found to be required for coagulation of the blood; its letter name comes from the Danish word koagulation.
A pure form was isolated and analyzed structurally in 1939; several related compounds having vitamin-K activity have since been isolated and synthesized.
The form of vitamin K that is important in mammalian tissue is of microbial origin.
A synthetic vitamin K precursor called menadione is used as a vitamin supplement.
Source: Britannica encyclcopedia
Vitamin D (Calcitriol) |
Vitamin D (Calcitriol) |
