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There has been conflicting evidence about whether or not B vitamins protect the brain, but a new study, published in the American Journal of Clinical Nutrition, sheds some light. For two years, researchers gave 168 elderly people who were experiencing mild mental decline either a placebo or daily B vitamins-800 mcg of folic acid, 20 mg of B6, and 500 mcg of B12. Brain scans showed that compared to the placebo, brain shrinkage was 40 percent less among those who took B vitamins and had high levels of omega-3 fatty acids, found in fish oil. B vitamins with low omega-3 levels did not produce improvement. Therapeutic amounts of fish oil generally start at 1,000 mg daily of a combination of EPA and DHA.