A diet high in fat and low in carbohydrates may slow the progression of Alzheimer’s disease, according to preliminary research.

A new study shows mice bred to develop Alzheimer’s disease showed less of the brain-clogging plaques associated with the disease when they were fed a high-fat, low-carbohydrate diet than mice fed a standard low-fat, high-carbohydrate diet.

Other studies in mice and in humans have suggested diets high in saturated fat and cholesterol may increase the risk of Alzheimer’s disease. But researchers say those studies did not examine the effects of a high-fat diet that is also low in carbohydrates, known as a ketogenic diet.

They say the results show that dietary approaches to treating Alzheimer’s disease should look at the interaction of various dietary elements on the formation of beta-amyloid plaques in the brain.

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Diet May Slow Alzheimer’s Disease

In the study, researchers analyzed the effects of a high-fat, low-carbohydrate diet in female mice bred to develop Alzheimer’s disease.

After 43 days on the ketogenic diet, researchers found beta-amyloid protein levels in the brain were reduced by 25 percent compared with a similar group of mice eating a standard low-fat and high-carb diet. Mice fed the ketogenic diet also lost weight.

However, despite these changes, mice on the high-fat, low-carb diet did not exhibit any changes in behavior in comparison with mice fed the standard low-fat, high-carbohydrate diet after 38 days.

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How Ketogenic Diets May Help

Researchers say the ketogenic diet’s effects on insulin and the related hormone, insulin-related growth factor-1 (IGF-1) may be responsible for the benefits found in this study.

"Insulin is often considered a storage hormone, since it promotes deposition of fat, but insulin may also work to encourage amyloid-beta production," says Richard Feinman, editor of the journal Nutrition and Metabolism, which published the study, in a news release.

In an accompanying editorial, Feinman says, "Although it is too early to tell how the results will fit into the treatment of [Alzheimer’s disease], the implication for diet in general is also important."

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By Jennifer Warner, reviewed by Louise Chang, MD

SOURCES: Van der Auwera, I. Nutrition and Metabolism, Oct. 16, 2005, online edition. News release, BioMed Central.