A UK study has cast doubt on claims that eating oily fish can protect against dementia in old age.
Data from a trial of more than 800 older people initially showed that those who eat plenty of oily fish seem to have better cognitive function. But factors such as education and mood explained most of the link. Researchers need to clarify what, if any, benefits fish oil has on the ageing brain, they wrote in the Journal of Nutrition, Health and Ageing.
In recent years, there has been increasing interest in diet as a way of preventing dementia. Much focus has been on omega 3 fatty acids found in oily fish, such as salmon and mackerel. And there are biological reasons, backed by tests in the laboratory, why in theory, these fatty acids would be neuroprotective.
The latest study found a significant association between eating a couple of portions of fish a week and better scores on tests of cognitive function. But when the researchers, from the London School of Hygiene and Tropical Medicine, took into account education and psychological health the association almost disappeared.