Fish oil (omega-3 fatty acid) supplements are sometimes used to help prevent heart disease, treat inflammatory conditions, and manage existing depression. But fish oil doesn’t prevent depression in healthy older adults, according to a randomized study led by Harvard psychiatrist Dr. Olivia Okereke and published online Dec. 21, 2021, by JAMA. Researchers studied about 18,000 depression-free adults (ages 50 or older) for five to seven years. About half were assigned to take a daily 1,000-miligram fish oil supplement. The other half took a placebo (an inactive pill). "This is the largest and longest randomized trial of fish oil in the prevention of depression. We found that it didn’t reduce depressive symptoms or boost mood in healthy older adults, and the supplements shouldn’t be used for this express purpose," says Dr. JoAnn Manson, the study’s senior author and chief of preventive medicine at Harvard-affiliated Brigham and Women’s Hospital. There may be other approaches that help stave off depression, such as getting enough sleep, exercising regularly, eating a plant-based diet, and staying socially connected — though we don’t have conclusive evidence any of these strategies work. "But we know a healthy lifestyle is tremendously important for preventing many chronic diseases, including heart disease, stroke, diabetes, and many forms of cancer," Manson says.
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