Yogurt, the Cultured Way to Eat Beneficial Bacteria

Written by: Geneva Collins

With antibacterial products all the rage and food poisoning scares dished up regularly in the media, it's refreshing to remember that not all microbes are harmful. Many brands of yogurt are teeming with a family of beneficial bacteria, dubbed probiotics, that have excited researchers about their potential as cancer preventives, cholesterol reducers, diarrhea cures and more.

Many of these claims are still more scintillating theory than proven science, but yogurt is an indisputably primo source of calcium, protein, B-12, riboflavin, potassium, magnesium and zinc.

You probably know that yogurt is fermented milk, but you may not understand how that creamy smooth treat in a cup differs from the sour smelling half-gallon that sat in your refrigerator too long.

In the United States, yogurt can't be called yogurt unless the milk has been inoculated with two bacteria: Lactobacillus bulgaricus and Streptococcus thermophilus. These live cultures convert some of the lactose in milk into lactic acid, which gives yogurt its tart taste. People who are lactose intolerant can usually eat yogurt because the bacteria can help digest lactose remaining in the yogurt even after it's been eaten.

In addition to the two required bacteria, however, many yogurt manufacturers add other cultures to the mix. These bacteria are generally referred to as probiotics, explains Mary Ellen Sanders, a research professor at California Polytechnic State University's Dairy Products Technology Center and a consultant with Dairy and Food Culture Technologies.

These bacteria, which include L. acidophilus, Bifidobacteria and L. casei, are native to the human digestive tract and are believed to provide health benefits by improving the mix of microflora in your gut. Unlike the two "required" bacteria strains, which are done in by strong stomach acids, many of the probiotic bacteria arrive in the intestines alive. According to Sanders, there's good evidence that probiotic cultures can relieve diarrhea caused by rotoviruses and antibiotics.

On the cancer front, research on animals suggests that different probiotic strains may decrease the level of tumors, but no human studies have been done yet. Alan Bakalinsky, Ph.D., associate professor of food science and technology at Oregon State University, and his colleagues have conducted experiments to see if yogurt bacteria and the compounds they produce can inactivate carcinogens in the colons of rats. "We started looking at this after [epidemiologic] reports showed that people who eat yogurt regularly get colon cancer less frequently than others," he said.

Elsewhere, scientists are investigating whether yogurt's beneficial bugs affect everything from immune system function to cholesterol levels to yeast infections to allergy symptoms. "There's simply not enough information from human studies to draw any definitive conclusions in these areas," says Sanders. "Even in areas where there have been lots of studies, effects are strain-and dose-specific."

In other words, scientists use specific strains and amounts of probiotic bacteria in their studies. Although most major brands of yogurt contain probiotic cultures, they may not be the exact strains tested or contain the high levels of bacteria used in scientific experiments.

Here are some ways to add more yogurt to your life that go beyond the usual smoothies and dips:

Yogurt as schmear. Pour a cup of plain yogurt into a paper coffee filter over a bowl and let it drain, refrigerated, for several hours. The resulting yogurt cheese, seasoned with herbs and scallions, makes a great bagel spread.
Yogurt as meal starter. For a classic cold soup for summer, grate two peeled and seeded cucumbers, then blend them with a quart of plain yogurt. Season with fresh parsley, mint, dill and garlic.
Yogurt as meat tenderizer. For terrific oven-fried chicken, peel the skin off 2-3 lbs. of chicken pieces, rub them all over with yogurt, and coat with seasoned cracker or cornflake crumbs. Bake in a 425-degree oven for about 40 minutes.

Geneva Collins, a food and health writer, has written extensively about nutrition topics for many consumer publications, including Nutrition Action Healthletter, The Female Patient and Atlantic Lifestyles, and has created healthy eating fact sheets for the National Institutes of Health.