The quest for a sharper mind as we age has fueled a booming market for brain-health supplements, from fish-oil capsules to postbiotics. But the evidence supporting these products is more complicated than it seems. A study found that omega-3 supplements were associated with faster cognitive decline in older adults, while another study suggested that multivitamins might slow biological aging. These findings raise questions about the effectiveness of supplements in improving brain health.
One approach to assessing these products is to examine whether people perform better on cognitive tests after taking a supplement. However, cognitive tests can be blunt instruments, particularly when studying healthy adults who are already functioning well. Stable performance may sometimes reflect the brain's ability to adapt or compensate.
Our ongoing better brain trial is designed to explore whether supplements and other nutrition-based products can change the way the brain supports cognitive performance, even when improvements are not immediately visible on a standard test. The findings are still being analyzed and have not yet been published in a peer-reviewed journal.
Nutrition affects the whole body, and the body communicates with the brain through metabolism, inflammation, blood vessels, hormones, and the gut-brain axis. Metabolomics, a technique that measures small molecules in biological samples, may help researchers explore whether people respond differently to the same intervention.
However, a cognitive-test score can only show whether a person completed a task more quickly or accurately. EEG can provide information about the brain activity associated with that performance, while metabolomics can reveal changes elsewhere in the body. Each method captures part of the picture, and a supplement should not be marketed as supporting memory simply because it changes a biomarker.
For consumers, caution is key. Supplements should not be treated as a shortcut to brain health. Evidence reviewed by the 2024 Lancet Commission on dementia prevention supports the importance of physical activity, social contact, and management of long-term health risks such as high blood pressure. In a market where claims can easily run ahead of evidence, measuring more does not remove uncertainty, but it can help researchers ask better questions and explain their findings more honestly.
