Fish oil supplements may not protect memory, new study suggests
Although fish oil supplements increased levels of a healthy omega-3 fat in the brain, they did not improve memory, thinking skills, or slow changes in the.
Fish oil supplements alone may not prevent memory loss. (Photo: Magnific)
Fish oil supplements have long been promoted as a simple way to protect memory and lower the risk of dementia. Many people take them, believing they can help keep the brain healthy as they grow older. However, a new study suggests the supplements may not offer the brain‑protecting benefits many expect.
The study, published in the journal eBioMedicine, found that although fish oil supplements increased levels of a healthy omega‑3 fat in the brain, they did not improve memory, thinking skills, or slow changes linked to Alzheimer’s disease.
Researchers studied 365 adults aged between 55 and 80 who were considered at higher risk of developing Alzheimer’s. The participants rarely ate fish, one of the richest natural sources of omega‑3 fatty acids.
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Participants were randomly assigned to receive either a daily fish oil supplement containing docosahexaenoic acid (DHA), an important omega‑3 fat, or a placebo. After six months, those taking the supplement had a 17 per cent increase in DHA levels in the fluid surrounding the brain and spinal cord.
Despite this increase, the researchers found no meaningful differences between the two groups after two years. People who took the supplements did not perform better on memory and thinking tests than those who received the placebo.
Brain scans also showed no reduction in the shrinkage of the hippocampus, a part of the brain that plays a key role in learning and memory and is commonly affected by Alzheimer’s.
"One of the most interesting findings is that even though the omega‑3s successfully reached the brain, participants did not experience measurable cognitive benefits," the researchers stated.
Experts caution, however, that the findings do not necessarily mean omega‑3 fatty acids have no role in brain health. Some argue the study cannot determine whether supplements prevent cognitive decline because participants were mentally healthy at the start. During the two‑year follow‑up, even those on placebo showed little or no decline in memory or thinking ability.
Because there was no significant decline in either group, experts say it is difficult to tell whether supplements could have slowed memory loss if participants had already been experiencing cognitive decline.
Previous research has consistently linked regular fish consumption and higher long‑term omega‑3 intake with a lower risk of dementia and Alzheimer’s. Scientists believe these benefits may take years to develop because DHA remains in the brain for a long time.
"The study does not rule out the possibility that long‑term omega‑3 intake helps maintain brain health, nor does it erase evidence linking higher fish consumption with a lower risk of dementia," said Mélanie Plourde, a professor and omega‑3 researcher at the University of Sherbrooke.
Experts stress that people should not stop eating foods naturally rich in omega‑3 fatty acids. Fatty fish such as salmon, sardines, trout and tuna remain excellent sources, while walnuts, flaxseeds, chia seeds and soy products also provide beneficial omega‑3s.
They also emphasise that protecting brain health requires more than one supplement. Regular physical activity, quality sleep, controlling blood pressure, staying socially active, and following healthy eating patterns such as the Mediterranean or MIND diet are all linked to a lower risk of cognitive decline.
People taking fish oil supplements for medical reasons, including high triglycerides, pregnancy, or because they rarely eat fish, should continue following advice from their healthcare provider.
While the latest findings suggest fish oil supplements alone may not prevent memory loss, experts say healthy eating and an active lifestyle remain the most reliable ways to support brain health as people age.
The results align with several previous studies questioning whether fish oil supplements can protect memory or prevent dementia. In 2017, the Multidomain Alzheimer Preventive Trial (MAPT), published in The Lancet, followed more than 1,600 older adults for three years and found that omega‑3 supplements did not significantly slow cognitive decline compared with a placebo.
Similar findings came from the VITAL Cognitive Study, published in 2022, which tracked more than 4,000 healthy older adults. Researchers found that taking a daily omega‑3 supplement for up to three years did not improve memory, thinking skills, or overall cognitive function.
A Cochrane Review combining evidence from several high‑quality trials also concluded that omega‑3 supplements did not improve memory, daily functioning, or quality of life in people living with Alzheimer’s. Another Cochrane review found little evidence that omega‑3 supplements prevent cognitive decline in healthy older adults.
Despite these findings, researchers stress that omega‑3 fatty acids remain important for brain health. Long‑term observational studies consistently link regular fish consumption with a lower risk of dementia and Alzheimer’s, suggesting that eating fish as part of a healthy diet over many years may offer greater benefits than supplements alone.