Miracle probiotics? Take claims with a pinch of salt, says study

A new study published in the journal Frontiers in Medicine cautions the public against believing and acting on information on probiotics online because most of the websites offering such information are not dependable and their sources are dubious.

The researchers say that Google does a good job of selecting and pushing up the best-quality websites when a consumer uses its search function. However, this doesn’t change the fact that most sites offering information about probiotics are commercial, backed by commercial or news outlets for the sake of profit. Researcher Pietro Ghezzi says that as a result, “These provide the least complete information, in terms of not discussing potential side effects or regulatory issues.”

In addition, they claim a lot of benefits for probiotics in diseases for which the evidence is not high-quality or has been collected from mouse studies rather than human clinical trials.

Intestinal bacteria 3d illustration Credit: nobeastsofierce / Shutterstock
Intestinal bacteria 3d illustration Credit: nobeastsofierce / Shutterstock

What are probiotics?

Probiotics are beneficial living organisms that may improve the state of health when taken internally in adequate amounts, both in general and in specific disease conditions. These are now available over the counter in hundreds of different formulations.

Many millions of Americans use probiotics for a range of health and disease indications, with the market being worth $40 billion in 2017. However, because advertising regulations for products claiming to have health benefits are more stringent in the US, the European market is smaller. The consumer base for these products is constantly on the rise, however, because of the global rise in the sale of products online.

This prompted the study based on the huge volume of often exaggerated health claims for probiotics presented by online sites and news media. The indication was to evaluate the accuracy of the news and information that the average member of the public would get to hear, see or read through an online search.

The study

The purpose of the study was to examine what would happen if the word probiotics was typed into a Google search box. The first 150 pages were examined with reference to their location online, such as commercial, news, governmental, health portal, and professional, making 8 categories in all.

The researchers then looked at the quality of the health information on the site, based on two criteria: the JAMA score and the HONcode certification. The JAMA score is based on four elements:

  • Authors are named
  • Date of publication
  • Website owner is indicated
  • Sources are referenced

The Health-On-the-Net (HON) code is assigned by an independent Swiss organization that evaluates the reliability and credibility of the health information presented online using 8 criteria, ranging from the author’s credentials and type of information, to relevant citations, justifiability, transparency (indicating editor and webmaster with contact information),financial disclosure and separation of advertisements from actual content in a clear manner.

Next, the diseases and pathological or physiological processes mentioned on the webpages mentioned were enumerated.

The organisms mentioned as being in the probiotics were listed.

Next, they assessed whether the site gave complete information, using four criteria:

  • whether scientific references were given
  • cautions that evidence was not always strong for all proposed probiotic benefits
  • safety issues with probiotics
  • regulatory status of the probiotic in question

Finally, they looked at the available scientific evidence for the efficacy of probiotics against these diseases for this purpose, they used the Cochrane library, which contains a vast amount of evidence-based information from clinical trials as well as meta-analyses.

The study also included a more practical aspect – the Google ranking of the websites and whether the information appeared within 3 or less clicks, which is the average range of the lay reader. Explains co-researcher Michael Goldman, “Often the public will not go past the first ten results - these will therefore have a higher visibility and impact.”

The results

The scientists found that in only 1 in 10 webpages were high-quality, in terms of meeting all four criteria. About 40% contained a caution as to possible limitation of benefits. About the same number referenced scientific work to support the claims they made. Only a quarter even spoke about possible adverse effects.

The researchers conclude that most of the first 150 results were linked to either commercial outlets (43%) or news providers (31%). However, the top 10 websites were health portals or commercial, at 44% and 22%. All 10 had an average JAMA score of 3 out of a possible 4. Among the 10, 44% had a HONcode seal but only 6% of the remaining websites.

Based on the analysis of the diseases mentioned in the webpages and the evidence that probiotics could help significantly in managing these conditions, the results showed that most of these top-ranked pages were providing misleading information. The average commercial website promoting probiotics was unlikely to provide reliable health information. The median completeness score was 2 and 1 for the top 10 and the remaining websites respectively.  

Many of them did not even mention the risks of using probiotics in individuals with weakened immunity, nor was the issue of regulatory restrictions brought up. And many of the inflated claims that probiotics had been found to be useful in treating specific conditions in humans were based, in fact, on findings in mouse experiments. Only less than a quarter had supporting evidence, and one in five had no evidence at all!

Strikingly, probiotics were strongly recommended for gastrointestinal disorders, strengthening the immune system, mental disorders and cardiovascular disorders – however, only the first area has correspondingly heavy experimental references, while the others have no Cochrane reviews at all. Even with gut disorders, the evidence is partial and uncertain, which is not reflected in the webpages.

On the other hand, Google analytics uses very tight standards to make sure that websites offering health information conform to high standards of quality. The fuller the information, and the greater the scientific support, the higher the ranking of the probiotics-linked page, according to the researchers. This is particularly so if the webpage is part of a health portal. This will push up science-based probiotics webpages to a higher rank than a commercial webpage.

However, the sheer volume of commercially oriented information is a great problem for people who want to truly know if taking probiotics could help them. In realistic terms, it is now up to the consumer to evaluate the source of information on any site. It is necessary to set up a new framework as well as policies to regulate how probiotic information is presented to the public to avoid false claims and misuse of this freedom.

Journal reference:

Online information on probiotics: does it match scientific evidence? Marie Neunez, Michel Goldman and Pietro Ghezzi. Frontiers in Medicine, January 2020. https://doi.org/10.3389/fmed.2019.00296. https://www.frontiersin.org/articles/10.3389/fmed.2019.00296/full

Dr. Liji Thomas

Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.


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