Nutrition and risk of dementia: overview and methodological issues.

After two decades of research on nutrition and dementia there is strong evidence for preventive effects of vitamin E, B vitamins, and n-3 fatty acids and deleterious effects of saturated fat on dementia. Among specific foods with evidence of neuroprotection are green leafy vegetables, other vegetables, berries, and seafood. A number of studies have examined dietary patterns, particularly the Mediterranean diet and DASH (Dietary Approaches to Stop Hypertension), neither of which is tailored to the specific foods and nutrients that have been identified as neuroprotective. A new diet called MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) incorporates many elements of the Mediterranean diet and DASH but with modifications that reflect current evidence for brain neuroprotection. The evidence in support of the relation of various nutrients and the Mediterranean diet to dementia has been inconsistent. The inconsistencies may be explained by inattention to nutrient/food intake levels in the interpretation of study findings and trial design, including a shifting metric among studies for scoring adherence to the Mediterranean diet. Future studies should pay particular attention to levels of intake in the design and analyses of nutritional studies.