SYDNEY, 2 FEB, 2010: Australian scientists at Melbourne's Deakin University have discovered the reason a diet rich in Omega-3 fatty acids can protect the brain from developing Alzheimers disease, reported China's Xinhua news agency on Tuesday.

Its protective powers stem from an ability to regulate the brain's natural level of zinc, which can prove toxic at elevated levels, cellular biologist and project leader Professor Leigh Ackland said.

She said previous research had shown a reduced incidence of neurodegenerative diseases in populations with a diet rich in Omega-3 fatty acids.

Ackland and her colleagues looked specifically at the relationship between one of these acids, docosahexaenoic acid (DHA) and zinc in neuronal cells which are responsible for transmitting signals in the brain.

"We found that when the level of DHA in neuronal cells drops, the level of zinc rises," she said.

"The higher levels of zinc can be toxic, resulting in cell death ... a key feature of neurodegenerative diseases, including Alzheimers.

"We believe that having omega-3 fatty acids in the diet helps keep the levels of zinc in the brain in balance and helps prevents the increase in levels that triggers cell death."

DHA is found most commonly in cold water fatty fish while a vegetarian source can be derived from seaweed.