December 27/Perth, Australia/The West Australian -- American researchers say they can prove that the omega-3 fatty acids found in fish oil can prevent Alzheimers disease.

In a major breakthrough in their understanding of the debilitating dementia, the scientists said they had found that the omega-3 docosahexaenoic acid (DHA) increased the production of LR11, a protein which is lacking in people with Alzheimers disease and is known to destroy another protein that forms the plaques associated with the condition.

Alzheimers is a neurodegenerative disease which causes memory loss, dementia and personality changes. Until now, researchers have speculated that fish oil may have an anti-Alzheimers effect but have had little evidence and have been unsure why it might be protective.

University of California researchers said when they gave even low-dose fish oil to rats, it increased levels of LR11 in their brains and the results were the same when tested on human brain cells in the laboratory. High levels of DHA caused "abundant" amounts of LR11 which seemed to protect against Alzheimers disease.

The positive results have already prompted the National Institutes of Health in the U.S. to start a major clinical trial which will see them give DHA to patients who already have Alzheimers disease.

Writing in the Journal of Neuroscience, geriatric medicine researcher Greg Cole said fatty acids like DHA were considered "essential" fatty acids because the body could not make them from sources other than diet. They were known to be critical to brain development and studies had previously linked lower levels of them to oxidative stress in the brains of Alzheimers patients.

He said for people who already had established Alzheimers it might be too late for fish oil supplements to have a noticeable effect, and more research was needed to work out the ideal dose to prevent the disease. While people who ate Mediterranean-type diets were likely to be consuming some of the necessary DHA through fish in their diet, in countries where people ate little fish, a higher dose of supplement might be needed.

About 500,000 Australians have dementia, with another 1000 diagnosed each year, and up to 70% of cases relate to Alzheimers disease. It is estimated that by 2050 almost 3% of the population will be affected by dementia.

From the January 7, 2008, Prepared Foods e-Flash