The research by scientists at the University of Kuopio in Finland involved 3,660 people age 65 and older who were healthy.

At the start of the study the participants underwent brain scans to detect silent brain infarcts, or small lesions in the brain that can cause loss of thinking skills, stroke or dementia and were also given questionnaires regarding the amount of fish in their diets.

The scans were then carried again five years later on 2,313 of the participants and it was found that those who ate fish high in omega-3 fatty acids, three times or more per week had an almost 26% lower risk of having the silent brain lesions that can cause dementia and stroke.

The fish, such as grilled or baked tuna, even when eaten just once a week led to a 13 percent lower risk of stroke and dementia and the researchers say people who regularly ate these types of fish had fewer changes in the white matter in their brains.

Dr. Jyrki Virtanen says eating tuna and other types of fish seems to help protect against memory loss and stroke and these results were not found in people who regularly ate fried fish.

Dr. Virtanen says the omega-3 fatty acids EPA and DHA appear to play a major role but more research is needed as to why these types of fish may have protective effects.

Other fish which contains high levels of DHA and EPA nutrients include salmon, mackerel, herring, sardines, and anchovies.

Dr. Virtanen says other research has shown that fish and fish oil can help prevent stroke, but this is one of the only studies that looks at it's effect on silent brain infarcts in healthy, older people.

Silent brain infarcts, which are only detected by brain scans, are found in about 20 percent of otherwise healthy elderly people.

The study is published in the current issue of Neurology, the medical journal of the American Academy of Neurology.

Produce from the organically and conventionally grown crops were then fed to animals over a two year period and intake and excretion of various minerals and trace elements were measured. Once again, the results showed there was no difference in retention of the elements regardless of how the crops were grown.

Dr B gel says: 'No systematic differences between cultivation systems representing organic and conventional production methods were found across the five crops so the study does not support the belief that organically grown foodstuffs generally contain more major and trace elements than conventionally grown foodstuffs.'

Dr Alan Baylis, honorary secretary of SCI's Bioresources Group, adds: 'Modern crop protection chemicals to control weeds, pests and diseases are extensively tested and stringently regulated, and once in the soil, mineral nutrients from natural or artificial fertilisers are chemically identical. Organic crops are often lower yielding and eating them is a lifestyle choice for those who can afford it.'

This research was supported by the International Centre for Research in Organic Food Systems (ICROFS), Denmark.

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