Eat fish or take a fish oil supplement? Research suggests eating fish regularly over a lifetime is good for the brain. But when it comes to staving off cognitive decline in seniors, fish oil supplements just don't cut it, a study finds. iStockphoto hide caption

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In a study of 4,000 pregnant women, fish accounted for only 7 percent of blood mercury levels. JackF/ hide caption

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If you eat fish, rather than take a fish-oil supplement, is there more likely to be a benefit? There's more than a suggestion that this is indeed the case. Verena J Matthew/iStockphoto hide caption

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