“Vitamins -Niacin: Vitamin B3, Nicotinamide, Nicotinic Acid – ” Biochemistry Notes for Class 12 Complete Notes for Class 12

Niacin: Vitamin B3, Nicotinamide, Nicotinic Acid


Niacin, or vitamin B3, is involved in energy production, normal enzyme function, digestion, promoting normal appetite, healthy skin, and nerves.

Food Sources for Niacin Sources include liver, fish, poultry, meat, peanuts, whole and enriched grain products.



Males: 16 mg/day; Females: 14 mg/day

Niacin Deficiency

Niacin deficiency is known to occur with alcoholism, protein malnourishment, low calorie diets, and diets high in refined carbohydrates. Pellagra is the disease state that occurs as a result of severe niacin deficiency. Symptoms include cramps, nausea, mental confusion, and skin problems.

Niacin toxicity

Consuming large doses of niacin supplements may cause flushed skin, rashes, or liver damage. Over consumption of niacin is not a problem if it is obtained through food.


Vitamin B6: Pyridoxine, Pyridoxal, Pyridoxamine

Vitamin B6, otherwise known as pyridoxine, pyridoxal or pyridoxamine, aids in protein metabolism and red blood cell formation. It is also involved in the body’s production of chemicals such as insulin and hemoglobin.


Food Sources for Vitamin B6

Sources include pork, meats, whole grains and cereals, legumes, and green, leafy vegetables. The RDA for vitamin B6 is 1.3 mg/day for adult males and females through age fifty.


Vitamin B6 Deficiency

Deficiency symptoms include skin disorders, dermatitis, cracks at corners of mouth, anemia, kidney stones, and nausea. A vitamin B6 deficiency in infants can cause mental confusion.


Too much Vitamin B6

Over consumption is rare, but excess doses of vitamin B6 over time have been known to result in nerve damage.


Folate: Folic Acid, Folacin

Folate, also known as folic acid or folacin, aids in protein metabolism, promoting red blood cell formation, and lowering the risk for neural tube birth defects. Folate may also play a role in controlling homocysteine levels, thus reducing the risk for coronary heart disease.


Food Sources for Folate

Sources of folate include liver, kidney, dark green leafy vegetables, meats, fish, whole grains, fortified grains and cereals, legumes, and citrus fruits. Not all whole grain products are fortified with folate..



The RDA for folate is 400 mcg/day for adult males and females. Pregnancy will increase the RDA for folate to 600 mcg/day.


Folate Deficiency

Folate deficiency affects cell growth and protein production, which can lead to overall impaired growth. Deficiency symptoms also include anemia and diarrhea. A folate deficiency in women who are pregnant or of child bearing age may result in the delivery of a baby with neural tube defects such as spina bifida.


Folate toxicity

Over consumption of folate offers no known benefits, and may mask B12 deficiency as well as interfere with some medications.


Vitamin B12: Cobalamin

Vitamin B12, also known as cobalamin, aids in the building of genetic material, production of normal red blood cells, and maintenance of the nervous system.


Food Sources for Vitamin B12

Vitamin B12 can only be found only in foods of animal origin such as meats, liver, kidney, fish, eggs, milk and milk products, oysters, shellfish. Some fortified foods may contain vitamin B12.



The Recommended Dietary Allowance (RDA) for vitamin B12 is 2.4 mcg/day for adult males and females Vitamin B12 Deficiency Vitamin B12 deficiency most commonly affects strict vegetarians (those who eat no animal products), infants of vegan mothers, and the elderly. Symptoms of deficiency include anemia, fatigue, neurological disorders, and degeneration of nerves resulting in numbness and tingling. In order to prevent vitamin B12 deficiency, a dietary supplement should be taken. Some people develop a B12 deficiency because they cannot absorb the vitamin through their stomach lining. This can be treated through vitamin B12 injections. Vitamin B12 toxicity No problems with overconsumption of vitamin B12 are known.

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