A randomized, double-blind, placebo-controlled clinical trial published in eBioMedicine (a journal of The Lancet) found that high-dose omega-3 supplements did not improve memory, cognition, or prevent brain cell loss in older adults without dementia but with risk factors for the condition.
Study Design and Participants
The two-year trial, conducted by researchers at Keck Medicine of USC (University of Southern California), included 365 participants aged 55 to 80. All participants had low baseline omega-3 levels and at least one dementia risk factor (such as obesity, a sedentary lifestyle, or hypertension). Additionally, nearly half (47%) carried at least one copy of the APOE4 gene, a known genetic risk factor for Alzheimer's disease.
Participants were divided into two groups:
- Treatment group: Received 2,000 milligrams per day of docosahexaenoic acid (DHA) derived from algae.
- Control group: Received a placebo.
- Both groups were also given a vitamin B complex.
Key Findings
- Biomarker Confirmation: After six months, DHA levels in the cerebrospinal fluid of the treatment group had risen by an average of 17%, confirming that the supplement was reaching the brain.
- Cognitive and Structural Outcomes: Over the 24-month period, no statistically significant improvements in cognitive performance, memory, or hippocampal volume were observed in the treatment group compared to the placebo group.
"Omega-3 supplements as a blunt instrument do not work." – Dr. Hussein Yassine, lead author
Statements from Researchers
Lead author Dr. Hussein Yassine (University of Southern California) stated that omega-3s from food may be more beneficial when consumed as part of a healthy lifestyle, including exercise and a Mediterranean diet.
Dr. Richard Isaacson (Institute for Neurodegenerative Diseases of Florida) commented that while omega-3s are critical for brain health, the study suggests they do not work in individuals with unhealthy lifestyles.
Researchers indicated they are investigating why omega-3s reached the brain without improving brain health, with a focus on factors such as health status, diet, genetics, and age.
Background and Context
Omega-3 fatty acids (EPA, DHA, and ALA) are essential for brain and heart health, but the human body does not produce them. They are obtained from fatty fish, nuts, seeds, and supplements.
The study challenges prior messaging that fish oil supplements protect against dementia and Alzheimer's disease.
The researchers emphasized that maintaining overall health through exercise, sleep, and a balanced diet remains important for reducing Alzheimer's risk. The study was funded by the National Institutes of Health and other sources.