These days it seems that every yogurt container on the grocery store shelf touts that it's chock-full of healthful probiotics, or "friendly bacteria." But since the U.S. Food and Drug Administration classifies products containing probiotics under the umbrella of "foods", which aren't subject to the same regulatory process as pharmaceutical drugs, there's no guarantee that the microorganisms are alive or will be beneficial to your health.
To better understand the potential benefits of microbial species in yogurt, researchers conducted two separate experiments involving mice and human twins. During a four-month period, the mice and twins consumed a commercially available probiotic-cultured yogurt. Researchers analyzed the participants' gut composition and behavior patterns before, during and after consumption. Health Day reports:
The result: The bacterial species in the yogurt did not take up fresh residence in either the human or animal consumers. Thus, the bacterial environment found in the guts of both mouse and man was roughly the same before and after yogurt consumption.
However, a subsequent urine analysis among the "humanized" mice unearthed "significant changes" in the activity of enzymes involved in metabolism, the team said.
The most prominent changes, the team further noted, had to do with the breakdown of carbohydrates.
Further down in the article, Stanford microbiologist Justin Sonnenburg, PhD, calls the study "interesting, subtle and incredibly well-designed" but notes that more research is need to fully determine the effect of consuming probiotics on human health. He says:
The fact that they found that a probiotic preparation doesn't do incredibly profound things to your existing gut composition, but instead impacts its function, is a theme that is coming up over and over again. And that is, that it matters less what microbes are actually there, and more what they are actually doing ... [But] it's still way too preliminary to say whether this means that probiotics are good or bad.
The findings were published in the latest issue of Science Translational Medicine. Funding for the studies came from the National Institutes of Health and Danone Research, an arm of the company that sells Dannon probiotic yogurt Activia.