Is Yogurt Really Good for You?

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Probiotics in yogurt do have limited positive effects. (Image credit: Arturo Osorno | Dreamstime)

The yogurt section in the grocery store has gotten pretty complicated. Instead of just choosing between regular and light, or fruit on the bottom versus premixed varieties, customers can now select what kind of bacteria they wish to devour with each cold spoonful.

Yogurt manufacturers have long marketed the "live, active cultures" in their products, but Dannon, Yoplait and other industry giants have recently introduced new brands of specialized yogurts containing trademarked microbial strains. Scientists continue to conduct research into how these microbes may contribute to healthy living. A study published in the British Medical Journal last year supported the medicinal benefits of yogurt, though in a limited setting. It showed that geriatric hospital patients who drank a probiotic yogurt beverage were less likely to suffer from diarrhea caused by ongoing antibiotic treatment. But some nutritionists remain skeptical about the potential advantages that probiotics can offer most people.

Despite its narrow range of participants, the study confirmed that probiotic yogurt aided many of those involved. "We have shown that simply giving a probiotic drink to elderly patients who are prescribed antibiotics reduces their risk of getting diarrhea," says Mary Hickson, a research dietician at Imperial College in London and the lead author of the study.

Gastrointestinal illness is a common side effect in an antibiotic’s battle against bacterial infection. Antibiotics don’t just go after the bad guys — they also kill some of the beneficial or neutral place-holding flora in our digestive tracts. This collateral damage allows deleterious organisms to establish themselves, often inflicting abdominal distress and discomfort as a result. Yogurt, like other "probiotic" foods, helps to promotes the growth of favorable bacteria in our digestive tracts. These microorganisms assist us in absorbing nutrients from our food and also occupy valuable real estate so that pathogens cannot proliferate and make us sick.

The British study monitored 113 patients taking antibiotics predominantly for respiratory ailments or prophylactic reasons before or after surgery. During antibiotic treatment, subjects consumed two daily servings of a Dannon probiotic yogurt drink called Actimel. Half of the participants drank a sterile milkshake as a placebo instead. Stool samples were analyzed for solidarity and for the presence of a particularly harmful bacterium, Clostridium difficile. This opportunistic microbe afflicts about one in five hospital patients on antibiotics.

The study found that just over one in 10 of those patients ingesting the probiotic product was stricken with diarrhea, but none caught C. difficile. In contrast, a third of those on the placebo had diarrhea, and 17 percent came down with a case of C. difficile.

"This is exciting research as it provides evidence for a new treatment that can be put into practice now and could save the health service money," says Hickson.

Her paper refers to a previous study led by Lorraine Kyne of University College Dublin in Ireland, which indicated that hospital patients with bouts of C. difficileincur almost $3,700 each in additional expenses. Increased hospital stays and antibiotic reinforcements to eradicate the infection lead to these higher bills, but fortunately for sufferers, insurance picks up the tab. All told though, Kyne’s paper conservatively estimates the annual cost overruns related to C. difficile as $1.1 billion in the United States alone. Comparatively, a full course of the Actimel supplements in Hickson’s study that help ward off the malignant microbe only costs about $100.

For the Dannon Company, the growing buzz about probiotics has translated into impressive sales figures for Actimel, which is sold under the name DanActive in the United States. In 2007, the product raked in approximately $1.8 billion in worldwide sales. As Dannon unveils new probiotic lines of yogurt, Michael Neuwirth, the senior director of public relations at the company, points to 30 published scientific studies that bolster the health benefits of DanActive and other probiotic foods.

But some consider Dannon’s claims to be dubious at best, and the impact of the British study as rather limited in scope. "It’s good news if you’re over 70 and so sick you need to be hospitalized and prescribed antibiotics," says David Schardt, senior nutritionist at the Center for Science in the Public Interest, a nutrition advocacy group based in Washington, D.C. Schardt also states in an e-mail that contrary to Dannon’s position, no studies conclusively show that DanActive "will help the people depicted in their commercials and on their Web site — harried mothers, active grandparents, busy kids — keep from getting sick."

Others have also taken issue with Dannon’s marketing strategies. In January, a Los Angeles firm served Dannon with a class-action lawsuit alleging that the company intentionally hyped its probiotic wares and made millions based on false claims.

Nonetheless, Roberta Lee, the medical director at the Continuum Center for Health and Healing, a holistic service center run by Beth Israel Medical Center in New York City, is convinced that probiotics are beneficial, especially when used in concert with other treatments. She says that probiotics have appeared in clinical settings in the past and their prevalence is on the rise.

"Seventy percent of our immune response is directed toward catching foreign invaders introduced through our guts," says Lee. As probiotics may offer a helping hand in tamping down unwelcome bodily invaders, Lee states: "I would be happy to recommend yogurt to a patient."

This answer is provided by Scienceline, a project of New York University's Science, Health and Environmental Reporting Program.

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