Eating any type of fish just once a week increases brain health, a study has revealed.
Just one fillet – grilled or baked – boosts grey matter, regardless of how much omega-3 fatty acid it contains.
Experts have previously said the anti-oxidant effect of omega-3 fatty acids – found in high amounts in fish, seeds, nuts and certain oils – are associated with improved brain health.
But the new study hints that eating any fish has health benefits.
The new research reveals that people who eat a diet including fish have larger brain volumes in areas associated with memory and cognition.
The findings add to growing evidence that lifestyle factors, such as diet, contribute to brain health later in life.
‘Our study shows that people who ate a diet that included baked or broiled (grilled), but not fried, fish have larger brain volumes in regions associated with memory and cognition,’ said Dr James Becker, professor of psychiatry at the University of Pittsburgh School of Medicine.
‘We did not find a relationship between omega-3 levels and these brain changes, which surprised us a little.
‘It led us to conclude that we were tapping into a more general set of lifestyle factors that were affecting brain health of which diet is just one part.’
Dr Cyrus Raji and the research team analysed data from 260 people who provided information on their dietary intake and had high-resolution brain MRI scans.
They were all found to be ‘cognitively normal’ at two time points during their participation in the 10 year health study that began in 1989 to identify risk factors for heart disease in people over 65.
Dr Raji said: ‘Participants answered questionnaires about their eating habits, such as how much fish did they eat and how was it prepared.
‘Baked or broiled (grilled) fish contains higher levels of omega-3s than fried fish because the fatty acids are destroyed in the high heat of frying, so we took that into consideration when we examined their brain scans.’
The researchers found that people who ate baked or grilled fish at least once a week had greater grey matter brain volumes in areas of the brain responsible for memory – by four per cent – and cognition at 14 per cent.
However, no association was found between the brain differences and blood levels of omega-3s, according to the study, which was published in the American Journal of Preventive Medicine.
Dr Becker explained: ‘This suggests that lifestyle factors, in this case eating fish, rather than biological factors contribute to structural changes in the brain.
‘A confluence of lifestyle factors likely are responsible for better brain health, and this reserve might prevent or delay cognitive problems that can develop later in life.’
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