What makes a superfood?

Salmon has at times been touted as a cancer preventive. Many nutritionists praise the health benefits of blueberries, kale and cinnamon bark. How does a food get elevated from the grocery aisle to superfood status? One expert, Phil Hagen, a preventive-medicine specialist at the Mayo Clinic's Healthy Living Program in Rochester, Minn., explains why there is more to food than a name.

Put a Label on It

The term superfood made its way into the popular lexicon about 15 years ago but there is no formal definition for it, says Dr. Hagen. "The term is often used to grab your attention or sell you something, so I would say, buyer beware," he says. "Even for foods that have been studied, the data is modest, slim or none at all."

The U.S. Centers for Disease Control and Prevention recently sought to classify "powerhouse" fruits and vegetables by their nutrient density—top billing went to watercress, followed by Chinese cabbage and chard. And while marketers are at liberty to label anything a superfood, Dr. Hagen doesn't believe any one food can be super. "There is not a food out there that has all 30 to 50 nutrients that we're supposed to consume regularly," he says.

Dr. Hagen recommends people eat as much nutrient-dense food as possible. "Fresh food is always better," he says.

Overlooking the Nutrients

There are about 40 substances the National Institutes of Health consider nutrients, mostly vitamins like A, B, D, K and E, along with trace minerals and certain fats and chemicals. "But this sidesteps this whole group of compounds that we've come to think of as health-protective, like the bioflavonoids and the polyphenols and other antioxidants, which show promise in preventing disease, but are not fully understood," says Dr. Hagen.

There is no recommended daily allowance for these compounds, so nutritionists can't put a number on how much people should consume. "Blueberries have gotten media attention because they have a lot of bioflavonoids in them, but I don't consider them any more super than strawberries," says Dr. Hagen. In fact, blueberries didn't even satisfy the CDC's new criteria for powerhouse foods, though strawberries did, Dr. Hagen says.

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