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- A new study found that fish oil supplements did not preserve cognition or brain volume in older adults at risk of Alzheimer’s disease.
- Brain health depends on a combination of factors, and omega-3 supplements alone may not be enough to prevent Alzheimer’s.
- Fish oil supplements may offer other benefits, but exercise, sleep, and a nutritious diet remain the foundation of brain health.
If you regularly take fish oil supplements hoping they’ll keep your memory sharp as you age, you may want to reconsider. New research suggests they may not help prevent the memory and brain changes associated with Alzheimer’s disease.
Testing Fish Oil for Alzheimer’s Prevention
Omega-3 fatty acids are known to support brain health in several ways, including reducing inflammation and supporting communication between brain cells.
Higher intake of omega-3s—from food or supplements—has been associated with a lower risk of dementia, leading scientists to believe that fish oil supplements may help prevent Alzheimer’s. But larger clinical trials haven’t been able to back that up, finding little or no improvement in memory or cognition from omega-3 supplements.
Researchers behind the new study, published in eBioMedicine, wanted to look deeper into this to find out whether the omega-3s from supplements actually reach the brain, or if they do, but provide no benefit.
They followed 365 adults ages 55 to 80 who were at elevated risk for Alzheimer’s and ate little omega-3-rich foods. About half also carried the APOE4 gene, the strongest genetic risk factor for Alzheimer’s disease.
Participants took either supplements with a high dose of docosahexaenoic acid (DHA)—the key omega-3 involved in brain function—or placebo pills every day for two years. Before the study began, they underwent MRI scans and tests to measure their memory and cognitive abilities.
After six months, participants taking fish oil supplements had a 17% average increase in DHA levels in their cerebrospinal fluid, the liquid that surrounds the brain and spinal cord, suggesting that the omega-3s had crossed into the central nervous system.
But after two years, follow-up cognitive tests showed no significant difference between the supplement and placebo groups. The fish oil supplements also didn’t appear to slow loss of volume in the hippocampus—a marker associated with Alzheimer’s disease.
Why the Supplements May Have Fallen Short
According to the study authors, fish oil supplements may simply not be enough to protect the brain from Alzheimer’s, which is influenced by a complex mix of age-related brain changes, genetics, lifestyle choices, and environmental factors.
One possible explanation is that supplements don’t provide the broader mix of nutrients and compounds found in foods, which may work together to support brain health.
“We think the lack of benefit reflects the need for a more holistic approach,” said study author Hussein Naji Yassine, MD, director of the USC Center for Personalized Brain Health. “These results suggest that we should focus less on single-supplement approaches and more on overall brain-healthy lifestyles.”
It’s worth noting that the study was able to demonstrate that omega-3s from supplements reached the area around the brain, and Yassine told Health that future research should explore the brain’s ability to absorb and use omega-3s.
Should You Keep Taking Fish Oil Supplements?
Based on existing research, experts said they wouldn’t recommend fish oil supplements solely to prevent Alzheimer’s disease or preserve cognition.
“What actually protects the brain isn’t a capsule,” Richard G. Stefanacci, DO, medical director of Inspira Living Independently for Elders (LIFE), told Health. “It’s exercise, sleep, blood pressure control, meaningful engagement, and the Mediterranean diet.”
Fish oil supplements may offer other health benefits, with the strongest evidence behind their ability to lower triglyceride levels, said Maggie Moon, MS, RD, a Los Angeles-based dietitian, brain health nutrition specialist, and author of The MIND Diet. But the findings for many other outcomes have been mixed.
Instead, experts recommend eating more foods rich in omega-3s, such as fatty fish, chia seeds, and walnuts. Fish is the best source of DHA, so a supplement may be beneficial for people who rarely or never eat fish, depending on individual needs. Ultimately, a healthcare provider can help determine if an omega-3 supplement is right for you.
