Fish oil supplements are a popular choice for those looking to protect their memory as they age. But a new two-year study suggests the capsules may not deliver the brain benefits that many consumers expect. Even when omega-3 fatty acids reached the brain, researchers found they did not enhance memory or prevent Alzheimer’s disease-related changes.
The clinical trial, led by researchers at the University of Southern California and published in eBioMedicine, involved 365 adults aged 55 to 80 years old. They rarely ate fish and had at least one risk factor for dementia. Researchers randomly assigned them to take either 2,000 milligrams of DHA daily, an omega-3 fatty acid found in fish oil, or a placebo.
The researchers saw no major differences in cognitive performance between the groups after two years. The brain scans also revealed that the supplements did not stop the hippocampus, a region that plays a role in learning and memory and is susceptible to changes associated with Alzheimer’s, from shrinking.
The results raise questions about the usefulness of taking high-dose fish oil supplements to prevent cognitive decline. But they don’t prove that omega-3 fatty acids are useless or that eating fish is bad for your health.
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Fish Oil Made It to the Brain, But Memory Didn’t Get Better
One of the most interesting findings of the study was that the supplements were successful in increasing DHA levels in the central nervous system. Researchers measured DHA in the cerebrospinal fluid of participants, the fluid that surrounds the brain and spinal cord. Participants who took the supplements saw DHA levels rise 17% on average over six months.
But the boost did not translate into higher test scores for memory and thinking after two years. The supplements didn’t protect against shrinkage in the hippocampus, either. The results suggest that more DHA in the brain does not necessarily translate into measurable cognitive benefits.
Almost half of the participants carried the APOE4 variant of a gene linked to higher risk of Alzheimer’s disease. The study did include people with this risk factor, but it did not determine whether certain subgroups might benefit from omega-3 supplements under certain circumstances.
Now researchers want to know if eating omega-3s in food leads to different results. A Mediterranean-style diet – high in fish, vegetables, fruits, whole grains, nuts and olive oil – has also been shown to be beneficial, as well as providing a wider range of nutrients than a single supplement. However, this trial did not compare the diet with fish oil capsules directly.
The message to consumers is clear: Don’t believe fish oil is a proven means of preventing Alzheimer’s or keeping your memory sharp. The researchers also note that other habits such as regular physical activity, quality sleep and a well-rounded diet are important parts of overall health.
The results are for a particular dose and a group of older adults at high risk of dementia, so they don’t answer every question about omega-3 supplements or their other potential uses. Anyone taking fish oil for a medical reason should consult a healthcare professional before altering their regimen.
