High dose DHA reaches the brain
A new clinical trial found that a high dose omega 3 supplement increased levels of an important fatty acid in the brain, but did not improve memory, thinking ability or brain structure in older adults considered at risk for dementia.
The study, published in eBioMedicine, examined whether daily supplementation with docosahexaenoic acid, known as DHA, could support brain health in people with risk factors for cognitive decline.
Study followed 365 older adults
Researchers at the University of Southern California enrolled 365 adults between the ages of 55 and 80.
None of the participants had dementia, but all had at least one risk factor linked to future cognitive decline. These included obesity, high blood pressure, high cholesterol or physical inactivity.
Participants also reported low dietary intake of omega 3 fatty acids before entering the study.
Participants received DHA or placebo
The adults were randomly assigned to take either 2,000 milligrams of DHA each day or a placebo.
The trial lasted 24 months, allowing researchers to assess whether long term supplementation could produce measurable changes in cognition or brain structure.
DHA is commonly found in fish oil and has long been studied because of its potential role in brain function and neurological health.
APOE ε4 carriers were a key focus
The trial placed special attention on people carrying the APOE ε4 gene variant.
This genetic variant is associated with a higher risk of Alzheimer’s disease, and nearly half of the study participants carried it.
Researchers wanted to determine whether people with this elevated genetic risk might respond differently to high dose DHA supplementation.
DHA increased in cerebrospinal fluid
The supplement successfully raised DHA levels in cerebrospinal fluid, which indicates that the nutrient reached the central nervous system.
This increase was observed both in participants who carried the APOE ε4 variant and in those who did not.
The finding showed that the supplement was biologically active and able to reach the brain environment.
No measurable improvement in cognition
Despite the increase in brain DHA levels, the supplement did not lead to better performance on cognitive tests.
Participants taking DHA showed no meaningful improvement in memory or thinking skills compared with those who received the placebo.
The results suggest that simply increasing DHA levels in the brain may not be enough to improve cognitive outcomes over a two year period in this population.
Brain scans showed no structural benefit
Researchers also examined brain imaging results, focusing especially on the hippocampus.
The hippocampus is an important region for memory and is commonly affected in Alzheimer’s disease.
Brain scans found no significant difference in hippocampal size between the DHA group and the placebo group.
Findings address a key omega 3 question
The trial helps clarify a major question in omega 3 research.
Some earlier studies had raised the possibility that omega 3 supplements failed to improve cognition because they did not sufficiently reach the brain.
In this study, DHA clearly entered the central nervous system, but that did not translate into better memory, thinking scores or hippocampal structure during the 24 month trial.
No major safety concerns reported
The study did not identify major safety problems linked to DHA supplementation.
Adverse event rates were similar between the DHA and placebo groups.
No serious adverse events were attributed to the treatment, suggesting that the supplement was generally well tolerated in the study population.
