Back-and-Forth Foods

On some days, they are hailed for their edible health virtues; on others, their culinary curse. Some studies boast of their abundance of life-extending antioxidants, while others warn of the poisons, fats, or other dangers they also contain.

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They are those "back-and-forth" foods and drinks that keep making news for different reasons -- adding to a recipe for confusion when it comes to their real role in your health.

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There's chocolate, which has been found to promote heart health -- while also clogging its arteries. Wine that dulls the senses but may also keep the mind sharp. Coffee that can cause nervousness, hand trembling, and rapid heartbeat while exciting researchers for apparently lowering risk of diabetes, Parkinson's disease, colon cancer, and even cavities. Wild salmon are known to be swimming with heart-healthy fatty acids -- and possibly, cancer-causing toxins, as well.

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Why these conflicting findings?

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"Science is evolutionary -- not revolutionary," says dietitian Kathleen Zelman, MPH, RD, director of nutrition for WebMD's Weight Loss Clinic, who also runs a private practice in Atlanta. "Generally, one study does not make a difference in the grand scheme of a certain food's role in your diet. But that doesn't stop it from making headlines."

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Especially when the latest findings suggest there are healthful properties in some of the most notorious vices in your kitchen, or possible dangers in foods that are generally praised for their nutritional gold.

Read Between the Headlines

So how do you know the real story behind the headlines to better determine how they should rate on your plate?

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"A lot depends on how, where, and with whom the study was conducted," says Marilyn Tanner, RD, spokeswoman for the American Dietetic Association and pediatric dietary study coordinator at Washington University School of Medicine in St. Louis. When you hear the latest health finding about these or any foods, she suggests you note these factors:

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• Where it's published. Bigger medical journals tend to publish better quality studies. "If it's published in the big journals -- TheJournal of the American Medical Association, TheNew England Journal of Medicine or the Journal of the American Dietetic Association -- it means something, and you should weigh those findings more than a study posted on a food manufacturer's web site," Tanner tells WebMD.

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• Where it was conducted. "Studies done in university settings are more likely to be trustworthy than those done at private labs or in the sponsoring companies' own lab," she says. "In multicenter studies, you've got different races, ethnic backgrounds, and populations, which can make food findings even more important. For instance, in the East and West Coasts, there is tons of fresh seafood, which would play a role in eating habits and health effects compared to doing a fish consumption study in the Midwest."

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• Its length and size. Generally, the larger and longer the study, the greater its credibility, and the more one can apply the results of the study to the general population.

Should You Have It or Not?

That said, here is the latest lowdown on some controversial cuisine: