Fish Oil and Alzheimer's Disease, Dementia

Consumption of Omega-3 Fatty Acids Were Not Associated With Impairments

ROTTERDAM, THE NETHERLANDS. Dutch researchers report an intriguing association between diet and the extent and rate of cognitive impairment in older men. Their study, part of the Zutphen Elderly Study, involved almost 1000 men born between 1900 and 1920. The men's intake of various food components was assessed (by personal interviews) in 1985 and 1990 and their cognitive function was evaluated in 1990 and 1993 using the Mini-Mental State Examination scale. The MMSE scale includes questions on orientation to time and place, registration, attention and calculation, recall, language, and visual construction. The researchers examined intake of linoleic acid, omega-3 fatty acids, beta-carotene, flavonoids, and vitamins C and E.

The researchers found that men with the highest intake of linoleic acid (mainly from margarine, butter, baking fats, sauces, and cheeses) had a 76% higher degree of cognitive impairment than did men with the lowest intake. This association held true even after adjusting for age, level of education, cigarette smoking, alcohol consumption, and calorie intake. The intake of omega-3 fatty acids, on the other hand, was not associated with any degree of impairment. Men with a high fish intake were less likely to be cognitively impaired than men with a low intake and their rate of decline over the period 1990-93 was half that of men rarely consuming fish. (Recall that fish, as well as fish oil, contain omega-3 fatty acids.) The intake of beta-carotene, flavonoids, and vitamins C and E was not associated with a greater or lesser degree of impairment. However, there was a clear correlation between a high vitamin C intake and a decline in cognitive function over the period 1990-93. Men with a high vitamin C intake were twice as likely to have experienced a decline as were men with a low intake. The researchers speculate that vitamin C may act as a pro-oxidant in the presence of free iron in the brain.
Kalmijn, S., et al. Polyunsaturated fatty acids, antioxidants, and cognitive function in very old men. American Journal of Epidemiology, Vol. 145, January 1, 1997, pp. 33-41

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