Dietary niacin (vitamin B3) may protect against age-related cognitive declines and development of Alzheimer’s disease in older people, according to an article in the August issue of the Journal of Neurology Neurosurgery and Psychiatry. Rich sources of niacin include lean meat, fish, legumes, nuts, dairy products, enriched grains and cereals, and coffee and tea.

The researchers based their findings on 3,718 people aged 65 years and older who did not have Alzheimer's disease at enrollment into the study. Participants completed a dietary questionnaire and were checked for any signs of cognitive decline three and six years after the start of the study.

At three years, a random sample of 815 people who had not initially had Alzheimer's disease was checked for clinical changes and their dietary niacin intake was assessed by means of food frequency questionnaires.

In the smaller group, 131 people were later diagnosed with Alzheimer's disease. After adjusting the results for age, gender, race, educational levels, and the ApoE gene - all important risk factors for the disease - people with the lowest food intake of niacin (an average of 12.6 mg/day) were 80 percent more likely to be diagnosed with Alzheimer's disease than those with the highest intake (22.4 mg/day).

An analysis of the larger group showed that the rate of cognitive decline among people with the highest niacin intake was almost half (44 percent) that of participants with the lowest intake.

Niacin has been prescribed for older people to prevent confusional states, but its role in Alzheimer's disease has not been thoroughly explored, according to the authors. They added that previous research has indicated that niacin has an important role in DNA synthesis and repair and neural cell signaling, and it acts as a potent antioxidant in brain cells.