Fish, Soy May Protect Against Alzheimer's

Dec. 7, 2004 -- Eating a diet high in fish and soy may help your brain fight the destructive plaque associated with Alzheimer's disease, according to new research.

The study showed that mice fed a diet rich in the omega-3 fatty acids found in fish and soy, produced more of a protein that helps eliminate the amyloid peptides that cause plaque in the brain.

The diet rich in omega-3 fatty acids stimulated production of the protein known as insulin-degrading enzyme or IDE, which may help protect the brain against Alzheimer's disease.

Researchers say the findings may also help explain why people with type 2 diabetes, who are resistant to the actions of insulin, are more likely to develop Alzheimer's disease due to their lack of this protein.

Protein Linked to Alzheimer's and Fat

In the study, researchers conducted two separate tests on the effects of IDE on the formation of amyloid plaque associated with Alzheimer's disease. The study appears in the Dec. 8 issue of The Journal of Neuroscience.

In the first, researchers tested human brain tissue taken from Alzheimer's patients and found that they had lower than normal levels of IDE protein. They also found that increasing insulin triggered an increase in IDE production in these tissue samples.

Next, researchers fed a group of mice a "bad" diet containing 6% total fat from safflower oil, which translates to about 15% of total calories from fat. Although that amount of fat is well below the 60% fat levels used in many other high-fat diet studies, researchers say the diet contained virtually no omega-3 fatty acids.

In contrast, another group of mice was fed a diet that was higher in fat (11% total fat) but also seven times higher in these fatty acids because it contained fish and soy.

Researchers found that mice fed the diet rich in soy and fish experienced an increase in the production of IDE, which may help destroy the amyloid peptides that cause destructive plaque in the brain. They say these diets may protect against Alzheimer's disease.

Although the study shows that eating a diet rich in omega-3 fatty acids may reduce the risk of Alzheimer's disease, researchers say more studies are needed to confirm the results.