Yogurt: The Curds and Whey to Health? : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 3)

Hilton authored a small study published in the March 1 issue of the Annals of Internal Medicine that showed eating yogurt containing Lactobacillus acidophilus reduced the incidence of vaginal infections. She plans to follow it up with a larger study using more patients and a variety of flavors and types of yogurt.

Until more proof is available, however, many doctors remain skeptical.

"Eating the yogurt doesn't do a whole heck of a lot" to treat yeast infections, says Michael Spence, M.D., the American College of Obstetricians and Gynecologists' expert on vaginitis and professor of obstetrics and gynecology at the Hahnemann University School of Medicine in Philadelphia.

Spence says even douching with plain yogurt, which puts the yogurt cultures in direct contact with the vagina, doesn't help.

"It's not going to do any harm, it's just going to prolong the agony," Spence says. "I've tried a lot of different [remedies] with my patients, including yogurt. It just doesn't work."

Other scientists have explored whether yogurt can reduce blood cholesterol levels. Several studies conducted on Maasai warriors in East Africa found that when they ate large quantities of yogurt, their cholesterol levels went down even though they gained weight.

The American Heart Association, however, discounts these results.

"I would not agree with those studies," says Margo Denke, M.D., who does research on nutrition and cardiovascular disease and serves on the AHA nutrition committee.

"The key to lowering cholesterol is to reduce saturated fat in the diet," she says. "There's some evidence that calcium can reduce saturated fat absorption, but it's only a small amount, a couple of grams."

Researchers have also explored yogurt's effects on cancer in rats. A few studies conducted in the early 1980s reported that yogurt decreased colon cancer tumors in rats, but those effects have not been duplicated in humans.

"There have been some interesting leads, but nothing has crystallized out of it," says Anthony Hitchins, an FDA microbiologist who formerly conducted and reviewed yogurt research at USDA's Human Nutrition Research Center.

Enthusiasm and research about yogurt's anti-tumor effects have fizzled, Hitchins says. "If something really exciting had come out of it, we would have heard about it."

Even if scientists have found no magical cures in yogurt, curds and whey still offer a nutritious snack. Consumers should be aware, however, that many different types of yogurt line dairy store shelves.

Preserved by Nature

"I would caution people that yogurts are not all the same," says Denke. If you're sticking to a low-fat diet, she recommends reading labels carefully.

Yogurt may contain significant levels of fat or have little at all. It may be swimming with live bacteria or it may have none at all. It may be plain or sweetened with natural or artificial flavors.

In any case, FDA requires all of these facts to appear on the label, and all yogurt products must meet certain FDA "standards of identity" requirements before they can be labeled with standardized terms.

The standards of identity require that yogurt products be cultured with L. bulgaricus and S. thermophilus bacteria. Certain other cultures may be present as well.

Yogurt has been made basically the same way for centuries. First, cow's milk (in many countries, it's goat's or sheep's milk) is pasteurized to kill unwanted bacteria. Then it's cooled to about 45 degrees Celsius (113 degrees Fahrenheit), and the yogurt bacteria are added.

The mixture is kept lukewarm for a number of hours, then chilled, allowing time for the bacteria to grow until the mixture becomes a tart, acidic gel.

Some 85 percent of yogurt sold in the United States is sweetened with fruit (strawberry heads the list) or flavored with other ingredients like coffee and vanilla. Some brands have the fruit already mixed in, while others require the consumer to stir it up before eating. (See "Yogurt Lingo.")

The fat in yogurt made from whole milk makes it creamy, while the low-fat and nonfat yogurts often contain ingredients such as milk solids or gelatin to produce a creamy consistency. Eight ounces of yogurt provides between 110 and 300 calories, depending on the milk-fat content and flavorings.

To make their products last longer on store shelves, manufacturers may heat-treat their yogurts after fermentation. While this doesn't affect the calcium content of the yogurt, it does kill the live cultures, the very ingredient many people expect in a yogurt.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.