The main results of the OPAL study were published in the American Journal of Clinical Nutrition in April 2010.
The study enrolled 867 participants aged 70-80 years from General Practice clinics in England and Wales.
Trial participants who all had good cognitive health at the start of the study were randomly assigned into two groups, one of which received fish oil capsules while the other group received a placebo for two years. Cognitive function was assessed at the start and end of the study by trained research nurses using a series of paper and pencil tests of memory and concentration.
After two years, those participants receiving fish oil capsules had significantly higher levels of omega-3 fatty acids in their blood than those participants receiving placebo capsules. However, cognitive function did not change over the course of the study in either group of participants and there was no evidence that the consumption of omega-3 fatty acids had a benefit for cognitive function in older people.
Dr. Alan Dangour the OPAL study lead researcher urged caution in interpreting these results:
From the data we have collected in the OPAL study there is no evidence of an important benefit for memory or concentration of increased omega-3 fatty acid consumption over a two year period among older people with good cognitive health.
However, it is important to keep in mind that poor cognitive function can take many years to develop and although this is the longest trial of its kind ever conducted -
- it may be that it was not long enough for any true beneficial effects to be detected among this healthy cohort of older people
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