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Few of us go to the lengths of biohacker Bryan Johnson, who reportedly takes hundreds of supplements a day.
But many people do take at least one, whether to support their immune system or protect their bones, in the hope it pays off down the line.
However, a new study shows that one common supplement taken by millions actually has much less effect than we think.
Omega-3 has long been marketed for its purported ability to sharpen cognitive function and protect the brain as we age.
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But a new study from Keck Medicine of the University of Southern California found that taking omega-3 levels supplements appears to do little to protect brain health.
The research tracked 365 adults between the ages of 55 and 80 who rarely ate fish - the most natural dietary source of omega-3 fatty acids - and were at elevated risk of developing Alzheimer's disease.
47 percent carried the APOE4 gene, widely recognised as the strongest known genetic risk factor for late-onset Alzheimer's.
In the double-blind trial, participants were randomly assigned to take either a daily fish oil supplement or a placebo. The supplement delivered 2,000 mg of docosahexaenoic acid (DHA), an omega-3 fatty acid closely tied to brain function.
Before assessing any cognitive impact, researchers first confirmed the nutrient was actually reaching its target. By measuring DHA levels in cerebrospinal fluid, the fluid surrounding the brain and spinal cord, they recorded an average 17% increase after six months, proving the supplement was being absorbed where it needed to be.
However, two years on, researchers found no improvement in memory or cognitive performance, and no evidence that the supplements slowed the loss of brain cells in regions linked to the disease.
“We all wish there was a silver bullet for preventing Alzheimer’s, but our findings showed that fish oil supplements do not appear to protect brain health,” said Hussein Naji Yassine, MD, director of the USC Center for Personalized Brain Health and lead investigator of the study. "While omega-3s play an important role in forming brain cell connections needed for cognition, our results do not support fish oil supplements as a preventive measure against Alzheimer’s.”
The scientists are now turning their attention to why omega-3s can successfully reach the brain without delivering associated benefits. One theory under investigation is that omega-3s may work more effectively when consumed naturally as part of a Mediterranean-style diet, which is rich in these fatty acids and has previously been associated with lower rates of Alzheimer's disease.
“We’re focused on better understanding how the brain processes omega-3s and whether factors, such as poor health, dietary pattern, genetic risk and age, may change the brain’s ability to effectively absorb and use omega-3s,” added Yassine. “We are working to develop medications that may help the brain better utilise these nutrients to preserve cognitive function.”
Outside of the study, the team argues that lifestyle factors remain the most effective way to protect brain health.
“Staying healthy throughout life remains the most powerful tool we have for reducing Alzheimer’s risk, including regular exercise, quality sleep and a balanced diet,” explained Yassine. “The brain is more likely to lose greater function if health issues in other parts of the body go unaddressed, in the same way that car engines stop working if regular maintenance is skipped.”
