Why probiotics may not always help, and could actually do harm

Health-4.jpg

PLENTY of people take probiotics in food or supplements in the hope of boosting their digestive health. But a new, small study suggests that some people may not benefit as much as others from these so-called good bacteria.
The study found that, when people consumed standard probiotic bacterial strains, some people’s guts appeared resistant to the bacteria, meaning the bacteria failed to successfully live in or colonize their guts. But for others, the bacteria readily grew and flourished in the gut.
The study suggests that not everyone may benefit equally from standard probiotic treatments, the researchers said.
“This suggests that probiotics should not be universally given as a ‘one-size-fits-all’ supplement,” study co-senior author Eran Elinav, an immunologist at the Weizmann Institute of Science in Israel, said in a statement. However, it may be possible to tailor probiotic treatments to the individual, based on the types of microbes already in his or her gut, as well as other factors, so that he or she gets the most benefit from probiotics, the researchers said.
In addition, a second study by the same group of researchers suggests that probiotics could have a potentially harmful effect if taken after antibiotics. Because both studies were small, however, more research is needed to confirm the findings.
Probiotics are live bacteria that are consumed with the aim of improving or maintaining the microbiome, or the many “good” bacteria that are found naturally in our guts, according to the Mayo Clinic.
A number of probiotic products are on the market, including yogurts containing probiotics, as well as supplements and skin creams, and an estimated 3.9 million Americans use such products. Some studies suggest that probiotics may help with diarrhea or symptoms of irritable bowel syndrome (IBS), but strong evidence to support their use for most health conditions is lacking, according to the National Center for Complementary and Integrative Health.
In addition, most studies that have looked at the effects of probiotics have used participants’ stool samples as a proxy for what’s going on in their guts. But it’s unclear whether stool samples really reflect the bacteria living in the gut, or whether some bacteria are shed in stool more easily, perhaps without properly settling in the gut.
In the new study, the researchers analyzed information from 15 healthy volunteers who took either a probiotic product containing 11 strains of bacteria, or a placebo, for four weeks. The participants also underwent colonoscopies and upper endoscopies before they took the probiotics or the placebo, and again after the four-week treatment period. (An upper endoscopy looks at the upper part of the digestive tract.) During these procedures, the researchers took samples from inside participants’ guts.
The researchers found that the probiotic bacteria were able to colonize the gut in six participants. The rest, however, were “resisters,” meaning the bacteria did not colonize their guts, even though the probiotic bacteria were shed in their stool.

Share this post

PinIt
    scroll to top