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VITAMINS: Vitamin B-3 (Niacin or Nicotinic Acid)

Overview of Vitamins | Vitamin A (and Beta Carotene) | Biotin (Vitamin H) | Vitamin B-1 (Thiamin) | Vitamin B-2 (Riboflavin) | Vitamin B-3 (Niacin or Nicotinic Acid) | Vitamin B-5 (Pantothenic Acid) | Vitamin B-6 (Pyridoxine) | Vitamin B-12 (Cobalamin) | Vitamin C (Ascorbic Acid) | Vitamin D | Vitamin E | Folate (Folic Acid) | Inositol | Choline


Vitamin B-3 (Niacin or Nicotinic Acid)

Functions of Niacin

  • Improves circulation and reduces the cholesterol level in the blood.
  • Maintains the nervous system.
  • Helps metabolize protein, sugar & fat.
  • Reduces high blood pressure.
  • Increases energy through proper utilization of food.
  • Prevents pellagra.
  • Helps maintain a healthy skin, tongue & digestive system.

Deficiency of Niacin

Pellagra is the classic niacin deficiency disease, is characterized by bilateral dermatitis, diarrhea, and dementia. Others include headaches, fatigue, mental depression, vague aches & pains, irritability, loss of appetite, insomnia, skin disorders, muscular weakness, indigestion, bad breath, canker sores

People with an increased risk of Niacin deficiency

  • Drinkers.
  • Women on the pill.
  • People on sleeping pills.

Recommended dietary allowance for Niacin

See Recommended dietary allowances for vitamins.

Food sources of Niacin

Good sources Niacin are yeast, meats including liver, cereals, legumes, seeds, milk, green leafy vegetables, and fish.

Clinical uses of Niacin

  • Nicotinic acid (but not nicotinamide) given as a drug in doses of 1.5-3 g/d improves the blood cholesterol profile.
  • Nicotinamide acts as a tumor-specific radiosensitizer, possibly due to its effect on vasorelaxation and increased tumor oxygenation.

Toxicity of Niacin

Large doses of nicotinic acid given to lower cholesterol may produce flushing of the skin, hyperuricemia, and hepatic abnormalities. These effects are reversed if the drug is reduced in amount or discontinued. The 1998 Tolerable Upper Intake Level (UL) of niacin, based on flushing produced by nicotinic acid, is 35 mg/d for adults.