Niacin (B3)

Niacin, also known as nicotinic acid and nicotinamide, is needed for the metabolism of food, the maintenance of healthy skin, nerves and the gastrointestinal tract. Niacin is also used in those all-important oxidation reduction reactions. A deficiency of niacin causes the disease, pellagra. In the past, this disease was often associated with the very poor and was also a major cause of mental illness. The symptoms of pellagra are sometimes referred to as the "three D's" -- diarrhea, dermatitis and dementia -- ultimately resulting in a fourth "D", death. The mouth is also affected by pellagra, which can cause the inside of the cheeks and tongue to become red and painful. Fortunately, high doses of niacin (150-300 mg.) can reverse the effects of this disease.

Niacin is found in protein-rich food such as meats, fish, brewer's yeast, milk, eggs, legumes, potatoes and peanuts. Niacin can also be prescribed in higher doses as a drug to help lower cholesterol (see How Cholesterol Works), but can cause side effects. The main side effects of high doses of niacin include flushing of the skin (due to dilating blood vessels), itching, headaches, cramps, nausea and skin eruptions.