Reduced risk of Alzheimer’s disease with high folate intake: the Baltimore Longitudinal Study of Aging
MM Corrada, CH Kawas, J Hallfrish, D Muller and R Brookmeyer;
Commented by , 21 Sep 2005
Aim of the Study
Examine whether total (diet plus supplements) intake of vitamins (E,C, carotenoids, folate, B6, B12) is associated with a reduced risk of AD.
Method
579 non-demented participants age 49 to 93 from the Baltimore Longitudinal Study of Aging completed dietary diaries and recorded supplement intakes for a 7-day period. The relative risk (RR) of AD in relation to total vitamin intake above or below recommended dietary allowance (RDA) was calculated using Cox regression.
Results
57 participants developed AD after a mean follow-up of 9.3 years. Higher intake of folate (RR, 0.41; 95% confidence interval [CI] 0.22 to 0.76), vitamin E (RR, 0.56; 95% CI, 0.30 to 1.06), vitamin B6 (RR, 0.41; 95% CI, 0.20 to 0.84) were associated individually with a decreased risk of AD after adjusting for age, gender, education, caloric intake. When analyzed together, only total intake of folate at or above the RDA (RR, 0.45; 95% CI, 0.21 to 0.97) was significant.
Professor Gauthier's comments
These epidemiological findings suggest that total (diet and supplements) intake of folate at or above RDA is associated with a reduced risk of AD in an elderly population.
A potential mechanism for this protection is the reduction of homocysteine levels. Homocysteine has been linked to vascular disease through direct effects on vascular endothelial cells, and to AD through impairing DNA repair in neurons or by direct toxicity to neuronal cells.
Interestingly, the USA and many other countries have initiated mandatory folate fortification of grain products in order to reduce neural tube defects. This public health decision aimed at pregnant women may be helpful to aging adults, although it is likely that additional supplementation would be required to reach RDA and protection against AD.
A randomized clinical trial would be required to prove benefit and safety of folate supplementation against AD.
This publication is from a new journal, Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, with Dr Zaven Khatchaturian as Editor-in-Chief.
Readers interested in other aspects of nutrition and aging can read the Journal of Nutrition, Health & Aging, with Dr Bruno Vellas as Editor-in-Chief.