Yogurt: bacteria to basics.

Cancer, high cholesterol, diarrhea, infections. You name it, somebody says that yogurt can prevent or cure it.

Is there anything to yogurt's reputation? There sure is. But that's the easy part. Making sure that your yogurt can do what the yogurt used by researchers does is another story.

Bulgaricus & Friends. It's the two bacteria that turn milk into yogurt that provide yogurt's clearest health benefit.

Lactobacillus bulgaricus and Streptococcus thermophilus help digest lactose, the milk sugar that about a quarter of all American adults (especially Blacks, Asians, Native Americans, and people of Mediterranean heritage) have difficulty handling. The beneficial bacteria break down the lactose into glucose and galactose, two sugars that nearly everyone can absorb.

So if you suffer cramps, bloating, or diarrhea when you drink milk, give yogurt a try. That way, you'll be replacing a calcium-rich food you can't handle with one you can.

Some manufacturers, including Dannon and Yoplait--the two largest--are now adding another bacterium, Lactobacillus acidophilus, to their yogurts.

Though it may offer other health benefits, acidophilus "doesn't help with lactose digestion enough to make much difference," says yogurt expert Dennis Saviano of the University of Minnesota.

A Strain Wreck. Millions of people believe that yogurt can do a lot more than digest lactose. Here's the real scoop:

* Cancer: Several studies in Europe have found that populations that eat large amounts of yogurt or other fermented milk products seem to have a lower risk of developing breast cancer.[1]

While the evidence is preliminary, studies in animals and humans suggest why a link might make sense. In our large intestines, acidophilus can prevent certain bacteria from creating carcinogens from our food or from the bile that our bodies secrete to digest fat.

When researchers from the New England Medical Center in Boston gave 21 people milk with L. acidophilus every day for four weeks, the harmful bacteria in their stools were two to four times less active than when they were given milk without acidophilus for four weeks.[2]

And in Sweden, 11 volunteers who had been eating fried beef patties were given milk with acidophilus. After three days, they had half the number of potentially cancer-causing substances in their urine and stools than after three days on fried beef and milk with no acidophilus.[3]

* Yeast and Other Infections: Yeast infections often are accompanied by a decline in levels of L. acidophilus, which is a normal inhabitant of the vagina. Since there is preliminary evidence that acidophilus can fight the growth of Candida albicans, which is responsible for most vaginal yeast infections, some doctors recommend that patients use acidophilus to clear up the condition.

In a small study in 1992, researchers at the Long Island Jewish Medical Center found that women with Candida infections who consumed eight ounces of acidophilus-containing yogurt every day for six months had fewer recurrences than women with Candida infections who ate no yogurt.[4]

And this year, researchers in Israel found that applying two to three teaspoons of acidophilus-containing yogurt directly into the vagina each day produced an immediate and lasting improvement in 28 of 32 pregnant women suffering from non-yeast bacterial vaginal infections.[5]

* Cholesterol: Can yogurt lower cholesterol? "That's what we found--the first time we studied it," says Sherwood Gorbach of the Tufts University School of Medicine. "But we couldn't see it when we repeated the experiments."

Here's a case where the strain may make all the difference. Stan Gilliland of Oklahoma State University has found that some strains of acidophilus act like a sponge and avidly soak up cholesterol in the intestines, which prevents it from being absorbed by the body. Other strains don't soak up as much.[6]

Don't bother looking for Gilliland's organisms, though. They're not yet available commercially.

* Diarrhea: There is no good evidence that any yogurt available in the U.S. can help treat diarrhea, says Tufts' Gorbach.

But Gorbach has isolated a strain called Lactobacillus casei GG that has been used successfully to treat traveler's diarrhea[7] and diarrhea in infants[8] in Europe. Unfortunately, it's not available in the U.S. At least not yet.

"We were so impressed by the data for this strain that we would be adding it to our yogurt today if the European company that licenses it had offered more reasonable terms," says Samuel Kaymen of Stonyfield Farm.

* Antibiotic Antidote: Many people eat yogurt when they're taking antibiotics because they think it replenishes the good bacteria that are killed by the drugs. But the two major bacteria found in all yogurts can't even implant themselves in the large intestine.

While they may help other bacteria gain a foothold, you might have a better chance of replenishing good bacteria with a yogurt that contains L. acidophilus or Bifidobacteria, since both are normally found in the large intestine. Check the label. They're almost always listed.

Buying Bugs. Can you increase your odds of finding a yogurt that will do you some good? You bet.

For a start, look for the words "live cultures" or "active cultures" on the label. And avoid "heat-treated" products. Their bacteria have been destroyed.

The industry's National Yogurt Association recently introduced a new "live and active cultures" seal to help consumers recognize yogurts that deliver at least ten million bacteria per gram, even on the date of expiration.

But the program is voluntary, and it costs manufacturers thousands of dollars. So, while the presence of a seal is good, its absence isn't necessarily bad.

A Pain in the Acidophilus. If you're buying yogurt to which acidophilus has been added, there's no way to tell how much you're getting.

Dannon says that it doesn't measure how much acidophilus consumers end up with. Yoplait, citing "competitive reasons," wouldn't tell us how much it puts in its yogurt, either. As for Kraft, whose Light N' Lively is the third leading brand, the presence--or absence--of acidophilus is a "trade secret."

Making matters worse, says an executive of a large yogurt manufacturer who asked not to be identified, is that "some companies just dump some acidophilus into their products so they can tell consumers their yogurt has it, but they don't know what they are doing and they don't care."

What's more, L. acidophilus competes with the L. bulgaricus that's in all yogurts. Unless the manufacturer is careful, the multiplying bulgaricus will squeeze out the acidophilus after a few days. If the bulgaricus doesn't get it, the acidophilus could still die before the yogurt reaches its expiration date. (So don't let your yogurt linger too long in the fridge.)

And there's no standard for which of the 200-or-so acidophilus strains companies should use. Will it reach your large intestine alive? Will it absorb cholesterol? Not all strains do. (Just try getting a company to tell you which strain it uses. Some may not even know.)

Hit-or-Miss-a-dophilus. Don't like yogurt? No sweat. Just pick up one of the dozens of supplements that promise to deliver the benefits of good bacteria. You've probably seen them--products with names like Allerdophilus, Sensidophilus, and Mega Potency Acidophilus.

Unfortunately, you may not be getting what you pay for.

In 1977, researchers Stan Gilliland and M.L. Speck found that only three of seven products claiming to contain acidophilus actually did. And in 1990, researchers at the University of Washington found that only two of the 11 acidophilus powders, capsules, and tablets they analyzed contained any.

Here's a little supplement-buying guide, compliments of Robert Sellars of leading culture supplier Chr. Hansen's:

1. Stick to powders that are packaged in dark brown glass bottles and that need to be refrigerated in the store and at home. "Capsules and tablets may be okay for a while," says Sellars, "but even under the best conditions they'll lose their potency after six months at room temperature--even faster if they pick up any moisture."

2. Take your supplement during a meal, preferably near the end, when your stomach is less acidic.

3. Drink one or two glasses of milk every day, if you can tolerate them. That will provide the good bacteria with one of their favorite foods, lactose (milk sugar).

[1] Foods, Nutrition and Immunity 1: 77, 1992.

[2] American Journal of Clinical Nutrition 39: 756, 1984.

[3] Microbial Ecology in Health and Disease 5: 59, 1992.

[4] Annals of Internal Medicine 116: 353, 1992.

[5] Acta Obstetricia et Gynecologica Scandinavica 72:17, 1993.

[6] Journal of Dairy Science 73: 905, 1990.

[7] Annals of Medicine 22: 53, 1990.

[8] Pediatrics 88: 90, 1991.