Fish oil supplements taken by millions to protect their brains from the ravages of age do nothing to slow natural mental decline, research suggests.
Scientists who monitored the progress of 4,000 study participants over five years found no evidence that omega-3 capsules kept them any sharper witted as they aged.
Other studies have associated regular fish consumption with lower rates of the eye condition age-related macular degeneration (AMD), heart disease, and dementia, as well as larger brain volumes.
It has been widely assumed that omega-3 fatty acids are behind the dietary benefits of fish. They are highly concentrated in the brain and appear to be important for the growth and repair of nerves.
But the new research indicates that fish oil supplements on their own are not enough to keep the brain young.
Emily Chew, from the US National Eye Institute – who led the Age-Related Eye Disease Study (Areds), said: “Contrary to popular belief, we didn’t see any benefit of omega-3 supplements for stopping cognitive decline.”
Contrary to popular belief, we didn’t see any benefit of omega-3 supplements for stopping cognitive decline
Earlier findings from the same study found that high doses of certain antioxidants and minerals could slow the progression of AMD, a leading cause of vision loss that results in damage to the retina of the eye with advancing age.
However, the scientists found that when additional omega-3 supplements were given to the participants, whose average age was around 73, it made no difference.
As well as investigating the AMD risk, the team also looked for signs of mental decline in the volunteers by giving them tests of memory, attention and thinking speed.
The cognition scores of all participants decreased by roughly the same amount over the five year period, irrespective of whether or not they had been taking omega-3 supplements.
Four groups of participants were given an inactive dummy pill, omega-3 on its own, two nutrients found in green leafy vegetables, or omega-3 plus the vegetable compounds.
The findings are published in the Journal of the American Medical Association.
Co-author Lenore Launer, from the US National Institute on Ageing, said: “The data add to our efforts to understand the relationship between dietary components and Alzheimer’s disease and cognitive decline.
“It may be, for example, that the timing of nutrients, or consuming them in a certain dietary pattern, has an impact. More research would be needed to see if dietary patterns or taking the supplements earlier in the development of diseases like Alzheimer’s would make a difference.”