Why an All-'Superfoods' Diet Is a Mistake

Blueberries, almonds, and salmon are all good, but you shouldn't limit yourself to them.

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Slide Show: 8 'Superfoods' and Their Alternatives

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We've all seen those lists of "superfoods"—certain fruits, nuts, and other foods that, advocates say, have health-boosting effects. But some people take those lists so seriously that they limit their food choices to what's on them. "They'll say, 'Every day I have Kashi with blueberries and almonds for breakfast, salmon on leafy greens with broccoli for lunch, and grilled chicken with sweet potato for dinner,'" says Mary Beth Augustine, a registered dietitian and senior integrative nutritionist for Beth Israel Continuum Center for Health and Healing in New York. The more educated they are and the more reading about health they've done, the more likely they are to strictly adhere to what they think is a perfect lineup of foods, she says.

[Slide show: Check out some alternatives to 8 superfoods.]

While that one-day menu is certainly healthful, getting into a rigid dietary routine isn't ideal, dieticians and nutrition scientists say. Many fruits and vegetables are chock full of nutrients. There are vitamins, minerals, and fiber, of course, but plants also have a host of special compounds they evolved to defend themselves from, for example, the sun's radiation, says Navindra Seeram, an assistant professor at the Bioactive Botanical Research Laboratory at the University of Rhode Island who studies the properties of berries. Those phytochemicals aren't essential for our own life and energy, but "research has shown that they may impart biological effects," says Seeram. (They're mostly studied for their beneficial effects, but some can have detrimental ones that we need to be aware of, such as grapefruit's interaction with some drugs.)

Certainly some foods have unique properties, says Seeram. Cranberry juice, for example, can protect against urinary tract infections. But researchers have identified only some of the thousands of active ingredients in fruits and vegetables (as well as other foods) and haven't begun to piece together all the ways they work together. There are some hints, however, that they do interrelate to have an impact on health. A study published in 2006 in the Journal of Nutrition compared two diets. Both provided eight to 10 servings of fruits and vegetables per day. But one diet included foods from 18 different botanical families; the other covered only five families. The researchers concluded that only the diverse diet "induced a significant reduction in DNA oxidation." (DNA oxidation, or oxidative damage, occurs when molecules called free radicals wreak havoc in the body. Antioxidants like some of the vitamins and phytochemicals found in plants are believed to reduce this damage.) In other words, as the researchers wrote, "smaller amounts of many phytochemicals may have greater beneficial effects than larger amounts of fewer phytochemicals."

Dawn Jackson Blatner, a Chicago-based dietitian and author of The Flexitarian Diet, agrees. "No one food is the superhighway to optimal health," she says. "The real magic happens when foods synergize and you get this great variety." Not only does variety give you wider exposure to the good stuff, it gives you less exposure to any detrimental phytochemicals or substances, such as the toxins in some mushrooms, says Augustine. To maximize the variety of fruits and veggies you get, dieticians advise people to "eat the rainbow," aiming to consume a variety of foods within each color group: red (including watermelon and tomatoes), red-purple (berries such as blueberries and blackberries, eggplant), orange (carrots and pumpkin), orange-yellow (citrus fruits, papaya), yellow-green (avocado and spinach), green (broccoli and cabbage), and white-green (garlic, onion, pears). (These categories are from UCLA scientist David Heber's What Color is Your Diet?)

"It's the same thing I teach kindergartners and preschoolers," Augustine says. The principle holds with nonplant foods, too. Eating a lot of the same kind of fish may expose you to possible contaminants, like mercury or PCBs, and deny you the benefits of many different species. At some point, says Seeram, science may be able to pinpoint ideal food pairings based on how their nutrients interact, but for now, the key is to simply aim for at least five servings of fruits and vegetables per day, across the color spectrum. Variety (within the confines of healthful foods, at least; being sure to take in Twinkies, Ho Hos, and Ding Dongs during a given week doesn't count) as a guiding force for eating? It doesn't boil down to an easy list, but yes, it can be that easy.