Lead researcher Greg Cole and colleagues at the David Geffen School of Medicine at the University of California, Los Angeles said the fish oil's omega-3 fatty acid -- docosahexaenoic acid, or DHA -- increases the production of a protein -- LR11 -- known to destroy the protein that forms the beta amyloids thought to be toxic to brain neurons and associated with Alzheimer's disease.

"We found that even low doses of DHA increased the levels of LR11 in rat neurons, while dietary DHA increased LR11 in brains of rats or older mice that had been genetically altered to develop Alzheimer's disease," Cole said in a statement.

Cole said high levels of DHA leading to abundant LR11 seem to protect against Alzheimer's while low LR11 levels lead to formation of the amyloid plaques.

Fatty acids like DHA are considered "essential" fatty acids because the body cannot make them and must obtain the through diet.

The findings are published in the Journal of Neuroscience,