Dietary niacin, vitamin B3, may protect against the development of Alzheimer's disease (AD) and the cognitive decline associated with ageing in older people, according to researchers from Centers for Disease Control and Prevention, Atlanta and Rush University Medical Center, Chicago, USA.

Dietary niacin, vitamin B3, may protect against the development of Alzheimer's disease (AD) and the cognitive decline associated with ageing in older people, according to researchers from Centers for Disease Control and Prevention, Atlanta and Rush University Medical Center, Chicago, USA. The research is published in the Journal of Neurology, Neurosurgery and Psychiatry.

The researchers conducted the study in 1993-2002 in a Chicago, USA, community of 6158 residents aged 65 years and older. Nutrient intake was determined by a food frequency questionnaire. Four cognitive tests were administered to all study participants at 3 year intervals in a 6 year follow up. A total of 3718 participants had dietary data and at least two cognitive assessments for analyses of cognitive change over a median of 5.5 years. Clinical evaluations were performed on a stratified random sample of 815 participants initially unaffected by AD, and 131 participants were diagnosed with 4 year incident AD by standardised criteria.

The researchers found that after adjusting the results for age, gender, race, educational levels, and the ApoE gene, those with the lowest food intake of niacin (an average of 12.6 mg/day) were 80% more likely to be diagnosed with AD than those with the highest intake (22.4 mg/day). The rate of cognitive decline among those with the highest niacin intake was 44% that of those with the lowest intake.

'In this prospective study, we observed a protective association of niacin against the development of AD and cognitive decline within normal levels of dietary intake, which could have substantial public health implications for disease prevention if confirmed by further research,' concluded the researchers.

Niacin rich food include meats, legumes, nuts, enriched grains/cereals, coffee, and tea. In addition, niacin is synthesised endogenously through the conversion of tryptophan, an amino acid that constitutes about 1% of the protein in foods.

The paper, 'Dietary niacin and the risk of incident Alzheimer's disease and of cognitive decline,' by M. C. Morris, D. A. Evans, J. L. Bienias, P. A. Scherr, C. C. Tangney, L. E. Hebert, D. A. Bennett, R. S. Wilson and N. Aggarwal was published in Journal of Neurology, Neurosurgery and Psychiatry (2004) 75: 1093-1099.

Contact: Dr. M. C. Morris, Rush Institute for Healthy Aging, 1645 W. Jackson, Ste. 675, Chicago, Illinois, IL 60612, USA.
Email: martha_c_morris@rush.edu