Vitamin may guard against mental decline.

The B vitamin niacin may protect people against Alzheimer's disease and other forms of mental decline, new research suggests. Lean meats, legumes, milk, coffee, and tea are some natural sources of niacin, and flour and cereals are fortified with the nutrient. Earlier studies had suggested that several other B vitamins counter dementia (SN: 3/2/02, p. 141).

A severe dietary shortage of niacin, or vitamin [B.sub.3], can lead to pellagra, a potentially fatal illness marked by rashes, diarrhea, confusion, and psychosis. Now rare, pellagra was epidemic in the southern United States in the early 20th century.

Looking for the mental effects of the vitamin on elderly people, Martha C. Morris of the Rush Institute for Healthy Aging in Chicago and her colleagues questioned 815 men and women, all at least 65 years old, to estimate their niacin intakes. None of the volunteers had Alzheimer's disease initially, but 131 developed it during an average study participation of 4 years.

People who consumed the least niacin--14.1 milligrams per day on average--were about three times as likely to develop Alzheimer's disease as were people who consumed at least 17 mg/day. The U.S. Department of Agriculture considers 14 mg and 16 mg adequate daily intakes of niacin for women and men, respectively.

In a larger group of volunteers, the researchers found that regardless of Alzheimer's, people consuming the most niacin experienced slower mental declines with age than did people consuming the least amount of the vitamin. The studies' results appear in the August Journal of Neurology, Neurosurgery, and Psychiatry.