Functions
Niacin is another water-soluble vitamin of the B complex, usually present in the forms nicotinic acid and niacinamide, with some differences in activity and side effects (see below). It is made in the body from the amino acid tryptophan, and acts as the coenzymes nicotinamide adenine dinucleotide (NAD) and its phosphate form (NADP) in cell respiration. It is also important in the production of energy from carbohydrates, fats and proteins, and in maintaining a healthy brain and digestive system, as well as nerves and skin.
Sources
Food sources are yeast extract, dried brewer's yeast, wheat bran, nuts, chicken, soya flour, meat, fatty fish, whole grains, cheese and dried fruits.
Uses
- Alcohol addiction
- Arthritis
- Blood cholesterol reduction (nicotinic acid, not niacinamide)
- Childhood schizophrenia
- Tobacco addiction
Deficiency
A niacin deficiency results in pellagra, which earlier killed thousands of people. This condition is characterized by,
- Coarse, dry and scaly skin
- Depression and anxiety
- Inflamed mouth and digestive tract
- Insomnia and irritability
- Loss of appetite, nausea and vomiting
- Rashes
Safety
Diabetics, persons with peptic ulcers, gout and pregnant women should consult a competent health professional before taking niacin supplements. Nicotinic acid may produce a flash or itch, but which disappears after about an hour. Niacin deficiency may be caused by alcoholism, anti-leukemia drugs, cancer, chronic diarrhea, malabsorption, prolonged fever, and a deficiency of vitamin B6, which negatively affects the body's ability to turn tryptophan into niacin. Long use of high niacin supplements may cause problems with the liver, digestive tract, and body metabolism. Time release supplements of niacin are associated with liver damage. Large doses of niacin can interfere with the laboratory measurement of blood sugar, and of catecholamines such as dopamine, epinephrine and norepinephrine.