Up Close and Edible: Yogurt

If milk does a body good, yogurt may do a body better. "It's one of the most perfect foods," says nutritionist Amy Jamieson-Petonic, a spokesperson for the American Dietetic Association. "It's a great source of calcium and of protein, and early research is pointing to some incredible health benefits."

Yogurt has a long and storied history—it's been eaten for thousands of years in Greece, where it has a reputation as a healthy staple and an aphrodisiac. But it wasn't until the start of the 20th century that yogurt was studied to determine its biological effects. The first to research yogurt was Nobel-prize-winning biologist Elie Metchnikov, who believed that lactobacilli—a strain of bacteria used in cultured milk—could ease gastrointestinal ills and help with longevity. Since then, numerous studies have suggested that yogurt and its so-called friendly bacteria, also known as probiotics, may actually enhance the immune system, have anticancer properties, help with allergies and yeast infections, lower cholesterol and even help you manage weight.

Probiotics are simply live bacteria that we eat, explains immunologist Gary Huffnagle of the University of Michigan Medical Center and one of the country's leading authorities on the study of these microbes. That's where yogurt comes in. The two microbes used in yogurt are Lactobacillus bulgaricus and Streptococcus thermophilus. These live organisms convert pasteurized milk to yogurt during the fermentation process, and they give yogurt its texture and taste.

Make sure you read the label before you eat: according to the National Yogurt Association, not all yogurts contain Lactobacillus acidophilus. Studies show that Lactobacillus is helpful in preventing antibiotic-associated diarrhea, says Huffnagle. And it also helps some women from contracting yeast infections. A study published in the Annals of Internal Medicine found that eating 8 ounces of yogurt containing L. acidophilus on a daily basis decreases the colonization of the organisms, leading to very common vaginal infection. To make sure the yogurt you buy has these cultures (some products do not contain live cultures), look for the yogurt association's Live & Active Cultures seal on the packaging.

Because this science is still in its early stages, the jury is out on yogurt's other potential health benefits. But nutritionists can still extol its virtues. An average eight-ounce serving of live and active culture yogurt contains approximately 30 percent of the Food and Drug Administration's Daily Recommended Value for calcium (about 100 more milligrams than 8 ounces of milk) and 20 percent of the Daily Value for protein. It's so protein-dense that yogurt is now considered a meat alternate by the U.S. Department of Agriculture. If you're lactose intolerant, don't despair. Because of its unique properties, many folks who suffer from cramping, bloating and diarrhea after consuming dairy products have no trouble with yogurt.

Your best bet is to stick with nonfat yogurt, which only has 100 calories, compared to about 140 for a full-fat variety. Though it's just fine to eat any one of the numerous flavor concoctions, Petonic recommends buying plain yogurt, and adding fruit, nuts or flaxseeds, for an extra boost. Now that's a carton of goodness.