Probiotics are a type of bacteria normally found in the human digestive tract that help with immunity and digestion. Now, we’ve all seen yogurts lining supermarket shelves boasting of "probiotics" — just how beneficial are they? Well, typically only a few strains of probiotic bacteria will have any health benefit at all, and product labeling isn’t always clear. It’s important to know which strains are in a product because each one yields a unique benefit.
As Gregor Reid, director of the Canadian Research and Development Center for Probiotics, puts it, "To say a product contains Lactobacillus is like saying you’re bringing George Clooney to a party. It may be the actor, or it may be an 85-year-old guy from Atlanta who just happens to be named George Clooney." So it's important to know which George Clooney you're eating. Dannon’s Lactobacillus casei DN114 001, for example, has been shown to reduce diarrhea. The common reasoning behind this is that consuming yogurt with probiotics like Dannon's strain helps re-establish a majority of "good bacteria" in the digestive tract.
But, according to Jeffrey Gordon, professor of pathology and immunology at the Washington University School of Medicine in St. Louis, that may not be the case. There are tens and tens of trillions of such organisms inside of us and a typical serving of yogurt contains only a few billion bacteria. So in relation to the number of bacteria already in your gut, it’s not a huge number. And so it's unlikely that consuming yogurt has any effect in substantially changing the makeup of bacteria in your digestive system. But, what he has discovered is that consumption of probiotics may aid in the digestion of certain polysaccharides, a type of complex sugar found in many fruits and vegetables such as apples, asparagus, carrots, oranges, and wheat. The caveat? With his subjects at least, the benefits began to wane after two weeks without consuming yogurt.
Gordon himself regularly consumes yogurt. Asked if he has noticed any health benefits, he says, "Not noticeable, but I enjoy the experience." Hmm.