Function:
Niacin (vitamin B3) functions as an important coenzyme involved in tissue respiration and fatty acid synthesis. The term niacin refers both to nicotinic acid and nicotinamide.

Recommended Dietary Allowance:
16 mg per day for men and 14 mg per day for women.

Deficiency:
Pellagra is the disease of niacin deficiency most frequently seen in populations eating a diet primarily derived from corn. It is characterized by diarrhea or constipation, weakness, insomnia, numbness, red painful mouth, pigmented skin rash, dementia, and ultimately death.

Sources:
Fish, poultry, red meat, legumes, and cereals are good food sources.

Toxicity and UL:
There is no toxicity from niacin contained in foods in the diet.

Niacin taken to lower blood cholesterol and triglyceride levels produces flushing as the first sign of excess. Prolonged use of very high levels (3 to 9 Grams per day) can result in liver damage and abnormal glucose metabolism.

The UL is 35 mg per day.

Recommendation:
Supplementation in someone with a well-rounded diet is not necessary.

In high doses nicotinic acid has been shown to favorably influence the level of blood cholesterol. The side effects from this treatment, however, limit it and should not be undertaken without the supervision of a physician.

For more information visit:
http://osu.orst.edu/dept/lpi/infocenter/vitamins/niacin/