Editor's note: The following is an excerpt from the new book Coffee Is Good for You: From Vitamin C and Organic Foods to Low-Carb and Detox Diets, the Truth About Diet and Nutrition Claims (Perigee, 2012), by Robert J. Davis, who teaches the Emory University's Rollins School of Public Health.

Trying to make sense of the seemingly endless stream of food and nutrition claims can be overwhelming. Remembering the following 10 rules will make the task easier and allow you to stay focused on what's really important:

1. Don't fixate on particular foods. Be wary of lists of miraculous "superfoods" you must eat or "toxic" foods you should never touch. Rather than worrying about squeezing one food or another into your diet, focus on your overall eating patterns, which should include plenty of vegetables, fruits, whole grains, fish, legumes, and good fats, and limited amounts of refined carbohydrates, junk food, red meat, and trans fats.

2. Look beyond narrow categories like carbs and calories. Many diet books and seals of approval on foods emphasize one or two factors, such as the calorie or carbohydrate count, while giving short shrift to other important things, like fiber, sodium, or trans fat. The fact that a hamburger is lower in calories than a salad doesn't necessarily make it a better option. Likewise, just because fruit punch or cereal has added vitamins doesn't mean it's healthful. What's important is the overall nutritional profile. You can get this from comprehensive food-scoring systems such as NuVal, which ranks the healthfulness of foods based on more than 30 factors.

3. Forget about fad diets. A plethora of weight-loss plans promise to melt away pounds quickly and easily. But in the long run, they rarely work. About 95 percent of dieters eventually regain lost weight. Instead of searching for the secret to skinniness, which doesn't exist, try to eat more healthfully and be mindful of how much you're consuming. Combined with exercise, this approach can prevent weight gain and, over time, lead to weight loss. And unlike dieting, it's something you can stick with long term.

4. Recognize the limits of vitamin pills. While vitamin and mineral supplements can help make up for deficiencies of nutrients, they generally don't live up to their billing when it comes to preventing disease, boosting energy, or improving your overall health. Supplements pack far less nutritional punch than food, which contains multiple nutrients that interact with one another and with other foods in a variety of complex ways. As a result, vitamin pills can't compensate for an unhealthful diet. And they can cause harm if you take too much of certain nutrients.

5. Ignore health claims on food packages and in ads. A few such claims, such as those related to sodium and high blood pressure, are officially approved by the FDA, but most aren't. They fall under a loophole that allows companies to use sneaky language like "helps maintain healthy cholesterol levels" or "helps support a healthy immune system." Because these phrases don't explicitly say that the food prevents or treats disease—even though that's what any normal person would infer—manufacturers don't have to provide any evidence. What's more, there are no strict definitions for frequently used terms such as all natural, low sugar, and made with whole grains or real fruit. Because it's virtually impossible to distinguish between legitimate and misleading claims by manufacturers, the best approach is to disregard them all and get your information from the Nutrition Facts panel on the package.

6. Don't be swayed by celebrities. A number of entertainers have authored books pushing particular diet regimens, and the media often report on celebrities' dietary "secrets." It can be tempting to believe people we admire who are thin, glamorous, and beautiful. But their fame and looks don't make them authorities on nutrition and health. Though celebrities may cite studies and so-called experts to make their case, their approaches can be scientifically baseless and even potentially harmful. Just as you wouldn't look to nutrition experts for entertainment, you shouldn't look to entertainers for nutrition advice.

7. Verify emails before forwarding them. The vast majority of emails about food and nutrition are half truths or outright hoaxes. If someone forwards you an email claiming, for example, that canola oil is toxic or that asparagus cures cancer, assume it's not true, no matter how scientific it sounds. Check it out with a reputable source like Snopes.com or Urbanlegends.about.com. Forwarding unconfirmed claims only adds to the hype, misinformation, and confusion.

8. Don't be influenced by just one study. When you encounter news reports about the latest study, don't jump to conclusions based on that alone. Remember that it's just one piece of a puzzle. What matters is the big picture—what scientists call the totality of the evidence. For a credible overview of the science, check out online sources such as the Nutrition Source from Harvard School of Public Health, or newsletters such as Nutrition Action Health letter, the Tufts Health & Nutrition Letter, and the Berkeley Wellness Letter. Or go to www.pubmed.gov and look up the research yourself.

9. Learn to live with ambiguity and change. We all want black and white answers. But that's not always possible when it comes to diet and health. We have to deal with, and distinguish among, various shades of gray. Understanding how different types of studies are conducted makes this much easier. Also, recognize that scientific information isn't set in stone; it's always evolving. This means advice will sometimes change as scientists learn more. Don't let that frustrate you. Instead, embrace the change and alter your eating habits accordingly.

10. Enjoy eating! As I said at the beginning of this book, all the admonitions about which foods we should and shouldn't consume can make eating a stressful chore. But it doesn't have to be that way. Using science as your guide, focus on the claims with the greatest credibility and relevance, and tune out the rest. That way, you'll feel less overwhelmed. While following sound nutrition advice is important for good health, it need not spoil your dinner. Bon appétit!


Reprinted from Coffee Is Good for You, by Robert J. Davis, by arrangement with Perigee, a member of Penguin Group (USA) Inc. Copyright © 2012 by Robert J. Davis.