Over the past few years, antioxidants—found in brightly colored fruits and vegetables, as well as legumes and grains—have landed on everyone's must-eat list. They're praised for mopping up potentially dangerous molecules in our bodies called free radicals, and research suggests that eating antioxidant-rich foods can improve memory, lower the risk of some cancers and even help keep you young. But the science on these good-for-you substances isn't so clear. Here's what you need to know:

The health benefits of antioxidants aren't as clear-cut as they sound. You've doubtless heard that blueberries are full of antioxidants that may protect against heart disease. But what does that really mean? It's true that one cup of blueberries contains more than 800 milligrams of polyphenols (antioxidants found in plants). But no one knows exactly how much of that amount our bodies absorb. No large-scale clinical trial has shown that people who eat blueberries are less likely to develop or die from any chronic disease. (It's incredibly hard to isolate cause and effect for one food with accuracy.) Instead, claims are many times pulled from smaller studies, like a recent blood pressure trial that found that consuming the equivalent of one cup of blueberries a day for eight weeks lowered BP by about 5 percent in postmenopausal women with prehypertension or hypertension. From data like this, people will then extrapolate that blueberries might be good for the heart.

Superfoods aren't necessarily the answer. Many people don't realize that the term superfood has no legal or regulated definition, and as a result is often used as a marketing ploy. Manufacturers and stores will label products as superfoods to indicate that they're full of nutrients, but they're not necessarily foods rich in antioxidants. A few that are: walnuts, kidney beans and dark leafy greens like kale.

Organic fruits and veggies don't contain more antioxidants. In a report published in the American Journal of Clinical Nutrition, scientists analyzed 46 studies that had measured nutrient levels in organically and conventionally grown produce. "We found no important differences in nutritional composition, including antioxidant content," says study coauthor Alan Dangour, PhD. Even with all the complicated research, the best nutritional advice is simple: Eat a diversity of produce, organic or otherwise. That's the best way to ensure you're getting a good mix of nutrients in your diet.

Some antioxidants may not be as beneficial as we initially thought. Continuing research indicates that we should tout their benefits with caution. Take, for instance, coenzyme Q10. A new McGill University animal study suggests that CoQ10 may not neutralize free radicals in the body. "Also, we may absorb little if any of the antioxidant from CoQ10-rich foods," says study coauthor and biologist Siegfried Hekimi, PhD. Bottom line: While many antioxidants still do the body good, it's best not to put all your health hopes in one blueberry—or Swiss chard or pomegranate—basket.

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