THE PROBLEM WITH PROBIOTICS

Lose weight. Cut cancer risk. Prevent colds. Those are just a few of the many health benefits ascribed to probiotics, the living microorganisms in the human digestive tract called the microbiome. But recent studies have begun to question these claims and even indicate that taking probiotic pills can be harmful in certain circumstances.

One study followed 46 melanoma patients through a course of immunotherapy. Almost half of them took probiotic supplements. These patients were 70 percent less likely to respond to the immunotherapy than those who did not take probiotics. And a systematic review of the research on probiotics found that there wasn’t enough evidence to prove a beneficial effect on anything other than diarrhea in children and a few other gastrointestinal issues.

The probiotics currently on the market may simply lack sufficient personalization. Evidence for that conclusion came from another recent study in which the microbiomes of participants who took a generic probiotic after a course of antibiotics took months to return to normal. Those treated with their own bacteria (collected before they took the antibiotics) bounced back within a few days.

In the future, researchers may be able to predict how different combinations of the hundreds of strains will behave within each person’s unique microbiome. Supplements today, though, contain only a few strains, so their helpfulness is limited.