Vitamins are organic compounds that organisms require in limited amounts but cannot synthesize themselves. They are classified based on their biological activity rather than their structure. Vitamins serve diverse biochemical functions as regulators, antioxidants, and precursors to enzyme cofactors involved in metabolism. There are two types of vitamins - water soluble vitamins like the B vitamins and vitamin C, and fat soluble vitamins A, D, E, and K. Vitamins play critical roles in many processes in the body like energy production, cell growth, immune function, and more. Deficiencies can lead to diseases, so obtaining vitamins through a balanced diet is important.

1. INTRODUCTION
Vitamin is an organic compound and a vital nutrient that an organism requires in
limited amounts. An organic chemical compound is called a vitamin when the organism
cannot synthesize the compound in sufficient quantities, and must be obtained through
the diet; thus, the term "vitamin" is conditional upon the circumstances and the
particular organism.
Vitamins are classified by their biological and chemical activity, not their
structure. Thus, each "vitamin" refers to a number of vitamer compounds that all show
the biological activity associated with a particular vitamin. Such a set of chemicals is
grouped under an alphabetized vitamin "generic descriptor" title, such as "vitamin A",
which includes the compounds retinal, retinol, and four known carotenoids.
Vitamins have diverse biochemical functions. Some, such as vitamin D, have
hormone-like functions as regulators of mineral metabolism, or regulators of cell and
tissue growth and differentiation (such as some forms of vitamin A). Others function
as antioxidants . The largest number of vitamins, the B complex vitamins, function as
precursors for enzyme cofactors, that help enzymes in their work
as catalysts in metabolism. In this role, vitamins may be tightly bound to enzymes as part
of prosthetic groups. They may also be less tightly bound to enzyme catalysts
as coenzymes, detachable molecules that function to carry chemical groups or electrons
between molecules Although these roles in assisting enzyme-substrate reactions are
vitamins' best-known function, the other vitamin functions are equally important.

2. WATER SOLUBLE VITAMINS
Eight of the water-soluble vitamins are known as the vitamin B-complex
group: thiamin (vitamin B1), riboflavin (vitamin B2), niacin
(vitamin B3), vitamin B6 (pyridoxine), folate (folic acid), vitamin
B12, biotin and pantothenic acid. The B vitamins are widely
distributed in foods, and their influence is felt in many parts of the
body. They function as coenzymes that help the body obtain energy
from food. The B vitamins are also important for normal appetite,
good vision, and healthy skin, nervous system, and red blood cell
formation.
Fat-Soluble Vitamins: A, D, E, and K
The fat-soluble vitamins, A, D, E, and K, are stored in the body for
long periods of time and generally pose a greater risk for toxicity
when consumed in excess than water-soluble vitamins. Eating a
normal, well-balanced diet will not lead to toxicity in otherwise
healthy individuals. However, taking vitamin supplements that
contain mega doses of vitamins A, D, E and K may lead to toxicity.
The body only needs small amounts of any vitamin.

3. Thiamin : Vitamin B1
Thiamin helps to release energy from foods, promotes normal appetite, and is important in maintaining
proper nervous system function. Sources -peas, pork, liver, and legumes, bread, pasta, rice, and tortillas.
thiamin deficiency : mental confusion, muscle weakness, wasting, water retention , impaired growth, and
beriberi.
Riboflavin: Vitamin B2
release energy from foods, promotes good vision, and healthy skin. Sources liver, eggs, dark green
vegetables, legumes, whole and milk. deficiency cracks at the corners of the mouth, dermatitis on nose and
lips, light sensitivity, cataracts, and a sore, red tongue.
Niacin: Vitamin B3, Nicotinamide, Nicotinic Acid.
energy production, normal enzyme function, digestion, promoting normal appetite, healthy skin, and nerves.
Sources include liver, fish, poultry, meat, peanuts, whole and enriched grain products. niacin deficiency -
Pellagra.
Vitamin B6: Pyridoxine, Pyridoxal, Pyridoxamine
protein metabolism and red blood cell formation. Sources pork, meats, whole grains and cereals, legumes,
and green, leafy vegetables. Deficiency symptoms skin disorders, dermatitis, cracks at corners of mouth,
anemia, kidney stones, and nausea.
Vitamin B12: Cobalamin
building of genetic material, production of normal red blood cells, and maintenance of the nervous
system. Meats, liver, kidney, fish, eggs, milk and milk products, oysters, shellfish. Anemia, fatigue,
neurological disorders, and degeneration of nerves and tingling.
Biotin
metabolism of fats, proteins and carbohydrates from food. Liver, kidney, egg yolk, milk, most fresh
vegetables, yeast breads and cereals. fatigue, loss of appetite, nausea, vomiting, depression, muscle pains,
heart abnormalities and anemia
Pantothenic Acid
Pantothenic Acid is involved in energy production, and aids in the formation of hormones and the
metabolism of fats, proteins, and carbohydrates from food. Sources liver, kidney, meats, egg yolk, whole
grains, and legumes.

5. Vitamin C: Ascorbic Acid, Ascorbate
vitamin C, also known as ascorbic acid or ascorbate, to remain in proper
working condition. Vitamin C benefits the body by holding cells together
through collagen synthesis; collagen is a connective tissue that holds muscles,
bones, and other tissues together. Vitamin C also aids in wound healing, bone
and tooth formation, strengthening blood vessel walls, improving immune
system function, increasing absorption and utilization of iron, and acting as an
antioxidant. best sources are citrus fruits. C deficiency may result in the
disease known as scurvy. vitamin C requirements are 1. Environmental stress,
such as air and noise pollution 2. Use of certain drugs, such as oral
contraceptives 3. Tissue healing of wounds 4. Growth (children from 0- 12
months, and pregnant women)
5. Fever and infection 6. Smoking.

7. Vitamin A: Retinol
Vitamin A, also called retinol, has many functions in the body. In addition to helping the
eyes adjust to light changes, vitamin A plays an important role in bone growth, tooth
development, reproduction, cell division, gene expression, and regulation of the immune
system. The skin, eyes, and mucous membranes of the mouth, nose, throat and lungs depend
on vitamin A to remain moist. Vitamin A is also an important antioxidant that may play a
role in the prevention of certain cancers.
Sources - dairy products, fish and liver. carrots, pumpkin, winter squash, dark green leafy
vegetables and apricots
Deficiency - xerophthalmia, Night blindness, decreased resistance to infections, faulty tooth
development, and slower bone growth.
Vitamin D
Vitamin D plays a critical role in the body’s use of calcium and phosphorous. It works
by increasing the amount of calcium absorbed from the small intestine, helping to form
and maintain bones. Vitamin D benefits the body by playing a role in immunity and
controlling cell growth. Children especially need adequate amounts of vitamin D to
develop strong bones and healthy teeth.
Sources - Milk , other dairy products , sunlight
Deficiency - rickets , osteomalacia , common cancers, autoimmune diseases,
hypertension, and infectious disease.

9. Vitamin E: Tocopherol
Vitamin E benefits the body by acting as an antioxidant, and protecting vitamins A andC, red
blood cells, and essential fatty acids from destruction. Might help prevent heart disease and
cancer. . Many studies show a link between regularly eating an antioxidant rich diet full of
fruits and vegetables, and a lower risk for heart disease, cancer, and several other diseases.
Sources - Vegetable oil, fruits and vegetables, grains, nuts, seeds, fortified cereals.
Deficiency - Premature infants
Vitamin K
Vitamin K is naturally produced by the bacteria in the intestines, and plays an essential
role in normal blood clotting, promoting bone health, and helping to produce proteins for
blood, bones, and kidneys.
Sources - Green, turnip greens, spinach, cauliflower, cabbage, soybean oil, cottonseed oil,
canola oil and olive oil.
Deficiency - Chronic diarrhea