Members of vitamin B-Complex: Chemistry, Functions And deficiency

vitamins are the substances that you need in your diet in small amounts to perform biological functions for maintaining normal health. During evolution the capacity to synthesis most of the vitamins was lost and hence humans need to obtain them from diet.

vitamins are widespread in occurrence including plants and animals. Normally all foodstuffs contain more than one vitamin in them. Plants can synthesis almost all vitamins but animals can synthesis only few. Human body can synthesis vitamin-A from its precursor carotene and vitamin-D from UV light irradiation of ergosterol and 7- dehydrocholesterol. All cells of the body store vitamins to some extent and they carryout functions in very low concentration hence daily requirement is low. They are most effective when taken orally. Now vitamins are also synthesized artificially.

members of vitamin b complex

Vitamin B complex are water soluble vitamins. There are 8 members in the vitamin B complex family. They play crucial role in red blood cells synthesis. Even though the members are chemically distinct, they exist together in the same food.


It is a sulfur containing compound and partially heat labile. Presence of pyrimidine ring and thiazole ring joined is the prominent feature.

Vitamin B1 is found in outer coat of rice and wheat. Yeast is also one of the good source. Whole cereals, pulses, oil seeds and nuts are also one of the source.

It is essential for carbohydrate metabolism and convert them into energy. Thiamine pyrophosphate is the prosthetic group of enzyme participated in oxidative decarboxylation of keto acids. It is used in functions of muscle contraction and relaxation and nerve signal conduction.

deficiency in adults results in beriberi. The main symptom of this is insomnia. In Wet beriberi cardiovascular system is affected and in Dry beriberi Central nervous system is affected. In infants it causes infantile beriberi.

VITAMIN B2 ( RIBOFLAVIN) : Riboflavin contains isoalloxazine ring and rabitol- a sugar alcohol in its structure. It is stable to heat and acidic pH.

It helps in releasing energy from proteins. It acts as prosthetic groups in many enzymes. It is important in electron transport chain, acts as antioxidant. It is also helpful in vision improvement. treatment of acne, muscle cramps involves vitamin B2.

green leafy vegetables are the main source of this. pulses, egg, milk also contain this vitamin. Fruits and some vegetables contain it in moderate amount.

Deficiency of vitamin B2 in humans causes oral facial and ocular lesions. It also caused hyperemia, hair loss and reproductive problems. In experimental animals deficiency resulted in growth retardation, cataract and corneal problems.

VITAMIN B3 (NIACIN): Niacin is the derivative of two pyridine derivatives called nicotinic acid and nicotinamide. It is stable to heat and alkaline pH.

This is found in legumes ,yeast, fish, whole grains and meat are also good sources.

This also plays a role in converting carbohydrates into glucose. It also functions in fat metabolism. And functioning of nervous system.

deficiency causes pellagra. In this disorder skin, gastrointestinal tract and nervous system are affected. Glossitis and stomatitis are also symptoms of niacin deficiency.

VITAMIN B5 ( PANTOTHENIC ACID): Chemically it is amide of beta-alanine and dihydroxy dimethyl butyric acid. It is unstable to acid or alkali but stable to heat.

cereals, legumes, meat, liver, milk and eggs are the good source f vitamin B5.

It has a role in breakdown of fats and carbohydrates. It is important in red blood cell formation. It is a component of coenzyme A. It is required for the synthesis of phosphopantotheine of fatty acid synthase complex.

its deficiency is rare in humans. But sometimes its deficiency symptoms may include insomnia, tiredness depression vomiting and pain in stomach area.

VITAMIN B6 (PYRIDOXINE): Certain compounds derived from pyridine like pyridoxine, pyridoxal and pyridoxamine show vitamin B6 activity. These are stable to heat but sensitive to light and alkali.

pulses, liver, whole grains and yeast contain adequate amount of this vitamin. Leafy vegetables, milk and eggs also contain moderate amount.

Deficiency in children causes epileptic form convolutions. Growth retardation problems also seen. Skin lesions are found. Microlytic hypochromic anemia is also a deficiency symptom.

VITAMIN B7 (BIOTIN): It is a sulfur containing vitamin and consists of imidazole ring. It is stable to heat but sensitive to alkaline medium.

Green leafy vegetables like cabbage, spinach, mint leaves, pulses, eggs and liver are good sources. Milk and cereals also contain adequate amount.

Biotin is the prosthetic group of enzymes like pyruvate carboxylase, acetyl coA carboxylase etc. It is involved in carrying of carbon dioxide in carboxylation reduction. It promotes perfect functioning of nervous system. It is important for liver metabolism. Helps in strengthening of hair and nails.

deficiency causes dermities , depression, muscular pain and anemia.

VITAMIN B9 (FOLIC ACID): It consists of pteridine nucleus, para aminobenzoic acid and glutamate. It is sensitive to light and acid. But it is stable to heat.

This is found in green leafy vegetables, Bengal gram, black gram and eggs, Coconut contains adequate amount of folic acid.

It works with vitamin C in production of new proteins. It also helps in synthesis of DNA. It also acts as carrier of carbon units.

In humans deficiency causes megaloblastic anemia, particularly in pregnant women. Bone marrow and intestinal cells are affected. Leucopenia, diarrhea and weakness are also some of the symptoms.

VITAMIN B12 ( CYANOCOBALAMINE) : Cyanocobalamine is made made of tetrapyrrole ring system known as corrin ring with a central cobalt atom.

Animal sources like kidney, liver, brain, fish and eggs are the good source.

It helps in making DNA and blood cells. helps in the maintenance of body’s nervous system.

weakness shortness of breath is of common symptoms of deficiency. It can also cause anemia and nerve problems.

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