University of Aberdeen researchers, jointly funded by the Alzheimer’s Research Trust and the Wellcome Trust, found that people who eat fish oils retained better mental ability in late adulthood compared to those that eat very little or none at all.
Importantly the researchers found that the benefit from fish oils was much greater in the majority of the population who lack one gene that is a specific risk factor for Alzheimer’s disease, compared to those who do have the risk gene.
The findings, reported in this month’s edition of the American Journal of Clinical Nutrition, show that genes and diet must be taken into account when measuring the effects of fish oils on mental ability.
Professor Lawrence Whalley, the lead researcher said, "The message here is that fish oil is good for 75% of the population but don’t expect to see any mental ability benefit if you carry a genetic risk factor which makes you more susceptible to Alzheimer’s disease.
"Twenty-five per cent of the population carries this risk factor. Our findings add to the body of research that suggests that a diet high in fish oils can reduce the risk of developing Alzheimer’s.
"Our research is also evidence for the interaction between genes and the environment in the ageing brain."
Previous population studies have shown that fish oil protects against Alzheimer’s disease but in this study the researchers showed this effect at a molecular level by measuring the amount of fatty acid, mainly derived from fish oils, present in red blood cells.
Rebecca Wood, Chief Executive of the Alzheimer’s Research Trust said, "Diet is an important risk factor of this devastating disease. Professor Whalley’s exciting research adds weight to a growing body of evidence showing that eating fish can reduce the risk of dementia.
"Further research is needed to confirm these findings are true in a larger population. If proven correct, dietary changes could one day become a readily available, effective weapon in the fight against Alzheimer’s."
Further findings in this area are expected later this year with the publication of a report from the London School of Hygiene and Tropical Medicine, commissioned by the Food Standards Agency, on fish oil supplementation and cognitive function in older people.
