“It’s easy to make small shifts in your life that would allow your indigenous organisms to not be harmed by things that are most likely unnecessary.”
Mazmanian said he also supports his microbiome by eating as our ancient ancestors did: organic foods, mostly plant-based, and meat only occasionally.
Some foods, like greens, oats, barley, beans, and artichokes naturally spur the growth of good bacteria, said Floch, of Yale, who has led a national effort to systematically gather information on probiotics.
Yogurt is the most frequently cited probiotic, and Floch, Xavier, and Lynch said they regularly eat yogurt, in part for its probiotic benefits. Mazmanian said he doesn’t eat much dairy because humans didn’t begin raising cattle until relatively recently in evolutionary history.
Most cultures have developed fermented foods that promote probiotic activity, including German sauerkraut, Korean kimchi, and French cheeses, said Dr. Marc Micozzi, of Rockport, a physician and anthropologist who wrote the medical school textbook “Fundamentals of Complementary and Alternative Medicine.” Beer and wine are probiotics, too, said Micozzi.
“They’ve been around for thousands of years,” he said, and “are part of our dietary history.”
Micozzi and others said they’re skeptical of the probiotic supplements sold at many natural food and grocery stores.
Most of the organisms in probiotic supplements come from dairy products, Mazmanian said, and most were chosen mainly because they have a long shelf life or for other reasons having nothing to do with effectiveness.
“There is exceedingly little evidence that anything on the shelves today, that there’s any benefit from them,” Mazmanian said.
Luckily, he and others said, there’s also “no evidence they do any harm,” particularly to people with healthy immune systems.
A few individual bacteria have been identified as helpful for particular diseases. There is good evidence, for example, that lactobacillus reuteri can be helpful against childhood diarrhea, according to research Floch published last year.
Science is nowhere near the point yet, though, of being able to prescribe specific bacteria to treat or prevent specific illnesses. That’s why most researchers suggest that the best approach for now is for each person to promote the health of his or her own microbial ecosystem.
“You have to think like an ecologist,” Micozzi said.
Karen Weintraub can be reached at firstname.lastname@example.org.