A recent study in The Journal of the American Medical Association found that seniors got no mental boost from taking daily omega-3 fatty acid supplements and antioxidant vitamins for four years. On the other hand, that doesn't mean eating a nutritious diet throughout life doesn't promote healthy aging.
The clinical trial involved more than 3,500 people, average age 73. Researchers were primarily testing the ability of daily nutritional supplements to prevent vision loss from age-related macular degeneration (AMD), which damages the light-sensing retina in the back of the eye. Participants also had tests of their mental function every other year in addition to annual eye exams.
The "eye vitamins" used in the study included 650 milligrams (mg) of omega-3 fatty acids, with or without 10 mg lutein and 2 mg zeaxanthin (nutrients commonly found in green leafy vegetables). Participants took either the dietary supplements or identical placebo pills. After five years, there was no difference in the overall rate of decline between the supplement and placebo groups.
The results may seem disappointing to those looking for nutritional support for healthy brain aging, but it isn't over yet. People in this study were already eating relatively nutritious diets when they started, so taking extra in a supplement was less likely to have an effect on them. It's also possible that taking omega-3 supplements in your 70s is too late to make a big difference, or that the dose used in this study was too low.