Ask the doctor: Should I take a probiotic?

Ask the doctor

Q. I'm hearing a lot about probiotics lately. Are they good for everyone?

A. You ask a great question, but you are asking it too soon: there hasn't been enough research yet for definitive answers. However, we are in the early days of a true revolution in medicine. We are discovering that the trillions of microbes that live on or in our bodies (like in the gut) may powerfully promote health. Swallowing capsules filled with these "healthy" types of live bacteria (probiotics) is one way of trying to improve health.

Does it work? In my opinion, there is some evidence that probiotics may help prevent or treat several different conditions: inflammatory bowel diseases, travelers' diarrhea, antibiotic-related diarrhea (including a severe form called C. difficile colitis), irritable bowel syndrome, and some allergies (particularly eczema). However, there are many different "healthy" bacteria. Different probiotics contain different bacteria, and we don't yet know which probiotics work for which conditions.

The microbes that live on and in us may even influence our risk of many major diseases, including type 2 diabetes, obesity, atherosclerosis, and various brain diseases. If these linkages are proved, then someday doctors may use probiotics to prevent and treat these diseases. If it comes, that day is well into the future.

For now, what I tell my patients is that if they find probiotics help them (for example, in improving the regularity of their bowel movements), I know of no reason not to take them.

— Anthony Komaroff, MD
Editor in Chief, Harvard Health Letter