By Linda Carroll

Most websites that provide information about probiotics are unreliable and often tout unproven health benefits, a new study finds.

After examining the first 150 websites turned up by a Google search, researchers concluded that the vast majority were run by companies advertising products or news outlets that offered incomplete information, often leaving out potential side effects, according to the report in Frontiers in Medicine.

“This study demonstrates that a number of online claims on the health benefits of probiotics are not supported by scientific evidence,” said coauthor Michel Goldman, a professor of immunology at the Universite Libre de Bruxelles, in Belgium, and chief editor of Frontiers in Medicine. “(For example,) online claims on the beneficial effects of probiotics in cancer are not supported by any evidence.”

That doesn’t mean the products have no use in promoting health, Goldman said in an email.

“In (developed) countries, probiotics can clearly be helpful in the management if infectious diarrhea, in pregnant women with gestational diabetes, and as an adjunct to food allergy desensitization therapy,” Goldman said. “They might also be beneficial in certain types of skin eczema and urogenital infections in women. In developing countries, probiotics were shown to prevent neonatal sepsis, an important cause of early-life deaths in those regions.”

To take a closer look at the information consumers might be finding online, Goldman and colleagues cleared histories and cookies from a computer and then searched on Google for “probiotics.” They focused their analysis on the top 150 results.

The researchers rated the web pages by four criteria: the presence of links to scientific references supporting health claims, cautionary notes about the level of evidence for alleged benefits, information about safety considerations and information on the regulatory status of the product.

They also checked to see if the sites had Health on the Net Foundation Code of Conduct (HONcode) certification, which is provided by an independent organization based in Switzerland that addresses the reliability and credibility of health information on a site.

To evaluate the scientific validity of claims made on the various websites, the researchers turned to the Cochrane library – a database of clinical trials and meta-analyses that pool evidence from earlier, smaller studies.

The researchers found that commercial sites and news outlets made up the majority of the 150 webpages. They found the commercial sites to be the least reliable, often not mentioning possible health risks or regulatory issues.

Overall, just 10% of sites met all four of the researchers’ criteria. Just 35% referenced scientific literature, 40% had a cautionary note about the purported benefits of the product and 25% mentioned potential side effects, they found.

“By and large, probiotics are safe,” Goldman said. However, he noted, there are a few reports of severe infections caused by probiotics in immunodeficient individuals including very-low birthweight newborns.

“The new study is a reminder for consumers that probiotics and other supplements are not regulated by the Food and Drug Administration,” said Julia Denison, clinical nutrition coordinator at the UPMC Magee-Women’s Hospital in Pittsburgh.

“And the claims are not 100% backed up by evidence,” Denison said. “A lot of people don’t know that.”

Many also don’t know they can get probiotics simply from consuming yogurt and other fermented foods, Denison said. “You don’t need to take a supplement to get probiotics,” she added.

For good information on dietary supplements, including probiotics, Denison recommends U.S. government websites, such as the site of the National Center for Complementary and Integrative Care of the National Institutes of Health (here:

SOURCE: Frontiers in Medicine, online January 15, 2020.