Claims: Made with "real fruit and yogurt," has 100 percent of the daily requirement for vitamin C, and is a good source of calcium.

Fact: This product contains fruit and yogurt, 100 percent of the RDA for vitamin C and 100 milligrams of calcium. It has 80 calories, 1 gram of saturated fat and 10 milligrams of sodium per serving, so it's a low-fat, low-saturated-fat, low-sodium food.

Concerns: David Ludwig, author of "Ending the Food Fight" (Houghton Mifflin, 2007) and director of the Optimal Weight for Life clinic at Children's Hospital, Boston, calls this "fake food," saying it's a "highly processed product, chock full of factory-produced ingredients, bearing little resemblance to anything from nature. The first four ingredients are variants of sugar. The minor amount of actual yogurt present is heat-treated after culturing, so the potentially beneficial probiotics (yogurt bacteria) are destroyed. Then, to top it all off, they add a host of artificial flavors and colors. Thus, the healthful associations with fruit and yogurt in the title are totally misleading." His advice: Just say no.

Bottom line: Low-fat yogurt with "real" fruit is the better option. However, Dawn Jackson Blatner, a spokesperson for the American Dietetic Association, says because of the added vitamin C and calcium in Yogos Rollers, it could be the lesser of the evils when compared to other snacks.

Claims: This is a healthful, organic, low-fat snack.

Facts: These squeezes are only 60 calories per tube, and they even have 1 gram of fiber. Not bad. Compared with Yogos Rollers, "Stonyfield YoKids is what we call a 'real food.' The first ingredient is organic low-fat milk; added sugar is listed once and comprises well under half the total calories; live probiotic (yogurt) cultures are present; and all ingredients are natural. Since it's actually very low in total fat, top it off with a few nuts (pecans, walnuts, almonds) for a balanced, nutritious snack," says Ludwig.

Concerns: Not too many.

Bottom line: This is a good choice for a snack.

Claim: The concept is that Hellmann's mayonnaise is made with "simple ingredients" such as eggs, oil and vinegar, so it represents "real food," not the over-processed foods marketed today.

Facts: The recipe for traditional mayonnaise calls for eggs, vegetable oil, vinegar and seasonings. Hellmann's, also known as Best Foods, uses these ingredients, as do other brands of mayonnaise. Foods such as mayonnaise and vegetable oils are excellent sources of heart-healthy unsaturated fats as well as vitamin E and essential fatty aids. A good diet should have 20 percent to 35 percent of calories from fat, predominantly unsaturated fat, so mayonnaise is a healthful spread, says Joan Salge Blake, a nutrition professor at Boston University.

Concerns: A tablespoon of mayonnaise provides 90 to 105 calories — this is very calorie-dense stuff. "If you want some mayo on your turkey sandwich or to make tuna salad, 1 to 2 teaspoons is a good rule of thumb," says Elisa Zied, a New York City dietitian and author of "Feed Your Family Right!" (Wiley, 2007).

Bottom line: Real or not, mayonnaise is very high in calories.

Claims: You get half a serving of real fruit in every ounce, and this is a nutritious snack. "This is stretching," according to Lona Sandon, a professor of nutrition at the University of Texas Southwestern Medical Center at Dallas. "What is it being compared to? What criteria are being used?" Also, Frito-Lay seems to imply that this is an all-natural product. Just go to their Web site, and you'll see their products shown on a farm, an "all-natural" setting.

Facts: Baked potato chips are actually lower in calories at 120 calories per ounce (one handful) compared with 130 for Flat Earth chips. Plus, the Flat Earth chips have more fat. In fact, when you look at the ingredients for the Flat Earth chips and compare them to baked potato chips, the chips look better. At least the first ingredient for the chips is dehydrated potatoes, whereas the Flat Earth Fruit or Veggie Crisps have flour as their first ingredients.

Concerns: It's easy to believe you're purchasing a "better-for-you" food and be lulled into a false sense that eating Flat Earth Crisps is healthy.

Bottom line: Chips of any kind are not replacements for real fruits and vegetables. This is just another type of snack food, no better than any other.

Charles Stuart Platkin is a nutrition and public-health advocate, and author of "Breaking the FAT Pattern" (Plume, 2006). Sign up for the free Diet Detective newsletter at www.dietdetective.com.