Study finds omega-3 supplements do not boost memory

A high dose of the omega-3 fat DHA made its way into the fluid around the brain, but it did not improve memory or thinking over two years in a trial of adults at elevated risk of dementia. Brain scans likewise showed no obvious benefit for people who took the supplement.

The findings address a problem that has long complicated earlier studies: when supplements do not sharpen thinking, researchers may not know whether the nutrient reached the brain or whether increasing its level simply had little effect.

Scientists at the University of Southern California reported the results in eBioMedicine. They studied 365 adults ages 55 to 80 who did not have dementia, consumed little omega-3 in their regular diets and had factors that increased their risk.

Nearly half of the participants carried APOE ε4, a hereditary gene variant linked to a higher likelihood of developing Alzheimer’s disease later in life. The team included people with and without the variant to see whether it changed the response to the supplement.

Volunteers were randomly assigned to receive either a daily capsule containing two grams of docosahexaenoic acid, or DHA, or a placebo. The study used DHA derived from algae, and both groups also received B vitamins.

Among participants who provided samples of the fluid surrounding the brain and spinal cord, DHA levels increased after six months of supplementation. The researchers found that the nutrient reached this fluid regardless of whether a participant carried the higher-risk gene variant.

Research into how Alzheimer’s risk genes affect brain circuits before memory loss has also highlighted the role of genetic differences.

However, the later cognitive testing told a different story. After two years, people who took DHA performed no better on memory and thinking tests than those given the comparison pill.

Brain imaging also found no clear difference in changes to the hippocampus, the brain region involved in forming memories. Together, the scans and cognitive tests provided no evidence of benefit, even though fluid measurements showed that DHA levels had changed.

About 38% of participants withdrew, mostly because of COVID-19-related disruptions. The two-year follow-up also limits what the study can say about a disease that often develops over a much longer period.

The trial focused on a standardized dose in adults with low omega-3 intake and at least one risk factor for dementia. It did not compare diets or examine what happens when people increase fish intake as part of broader dietary changes.

The results help point researchers toward the next question: how the brain uses DHA after it arrives, and whether that process matters more for thinking than the amount that reaches the surrounding fluid.

If you are interested in this topic, please read articles about Omega 3 Supplements Linked to Faster Cognitive Decline Study Finds, and A Simple Nutrient May Protect the Brain from Alzheimer’s Disease.

For more information, please see articles about How Mediterranean and Mind Diets Could Protect Against Alzheimer’s, and Study Finds Vitamin D May Help Memory but Slow the Brain in Older People.

Source: University of Southern California.