Fat in Diet Linked With Alzheimer's
Good Fats Play Protective Role; Vitamins Don't Help at All
Feb. 18, 2003 -- Diet seems to be linked to Alzheimer's disease, especially fat, according to two new studies. Sticking to a diet high in "good fats" -- from nuts, fatty fish, vegetable oils -- seems to lower risk, while eating fried foods and other "bad fats" increases risk. However, antioxidant vitamins don't have much effect in preventing dementia and Alzheimer's.
The studies appear in this month's issue of Archives of Neurology. They add to a growing body of data pointing to diet as a factor in staying sharp in old age. A few animal studies -- and one large study of older adults -- have suggested that a diet high in total fat, saturated "bad" fat, and cholesterol is bad for the brain.
But the new data, using human subjects, do not show any significant risk of developing Alzheimer's from total fat intake or cholesterol. Only saturated fats take the blame.
In the first study, researchers asked 815 seniors -- all unaffected by Alzheimer's symptoms -- what foods they ate regularly. They gave the same group a similar questionnaire about two years later. Researchers then tracked the seniors' health for four more years and found that 131 had developed Alzheimer's.
The bad news: Those who reported eating more saturated and hydrogenated fats -- from red meat, fried foods, and packaged foods like cookies, cakes, and chips -- were twice as likely to develop Alzheimer's.
A diet rich in polyunsaturated and monounsaturated fats -- from vegetable oils, avocados, and fatty fish such as salmon and tuna -- carried less risk of dementia, writes lead researcher Martha Clare Morris, ScD, with the Rush Institute for Healthy Aging at Rush-Presbyterian/St. Luke's Medical Center in Chicago.
The second study looks at the popular belief that vitamins C and E and beta-carotene prevent Alzheimer's. Some researchers have theorized that damaging and unstable compounds called free radicals in the bloodstream may damage nerve cells, leading to dementia -- and that the antioxidant effects of C, E, and beta-carotene may reduce this cell damage.
Researchers tracked the eating habits of 980 elderly people -- all without dementia symptoms -- for about four years. They found that 242 people developed Alzheimer's during that time. However, their vitamin intake did not seem to be linked with their dementia.
"Neither dietary, supplemental, nor total intake of carotenes and vitamins C and E was associated with a decreased risk," writes lead researcher Jose A. Luchsinger, MD, with Columbia University in New York.
SOURCE: Archives of Neurology, February 2003.