The mass marketing of unregulated probiotics for general human health is coming under fire. Despite some benefit of selected strains in defined gastrointestinal contexts such as post-infectious diarrhea, post-colectomy pouchitis, and remission maintenance in ulcerative colitis, concerns are growing about the sale of untested consumer formulations. There are claims of unsubstantiated benefits for healthy people but make no mention of potential risks and offer no guarantee of potency and purity.
“Consumers and physicians should not assume that the label on probiotic supplements provides adequate information to determine if consuming the live microorganism is worth the risk,” wrote Pieter A. Cohen, MD
, of Harvard Medical School in Boston, in a viewpoint article in
JAMA Internal Medicine.
He pointed out that advertised indications notwithstanding, no large, long-term clinical trials have proven that probiotics offer clinical benefits for people who are already healthy. Yet U.S. manufacturers are free to promote supplements as doing just that: “There are few restrictions on structure and/or function claims, such as ‘boosts digestive health’ or ‘supports the immune system’ on supplement labels, and information about potential adverse effects is not required.”
Consumers may thus not be aware of the possible risks of ingesting live bacteria, including opportunistic infections, allergic reactions, and the introduction of new genes into the microbiome that might confer antibiotic resistance, he said.
Asked for his perspective, Jason K. Hou, MD, of Baylor College of Medicine in Houston, told MedPage Today that the piece made some interesting points about the risk of probiotics — particularly the potential for gene transfer and antibiotic resistance. “There’s not a lot of clinical evidence currently to strongly advocate for their use, but neither are there a lot of data showing that probiotics cause adverse clinical events.” He added that Cohen’s article highlights the need to monitor the effects of probiotics as their use becomes more widespread.
‘Creative Advertising and Hype’
In the article, Cohen noted that with small studies used to put a favorable spin on probiotics, “creative advertising and hype” around the power of the gut microbiome are driving enthusiasm for commercial probiotics. For example, in the decade 2001-02 to 2011-12,
consumption of probiotic supplements more than doubled in the United States. Consumption is highest among college-educated adults, with 3.5% reporting use of probiotic supplements within the past 30 days. In addition, in a recent Nielsen survey, 20% of respondents said probiotics are important for health.
Clinicians frequently prescribe them as well, with a
2016 report on 145 U.S. hospitals finding that 2.6% of inpatients had received probiotics during their hospitalizations.
In terms of safety, a 2018 review by
Aïda Bafeta and colleagues found that information about harms in randomized controlled trials assessing probiotics, prebiotics, and synbiotics was often lacking or inadequate, leading the authors to state: “We cannot broadly conclude that that these interventions are safe without reporting safety data.”
And in a
2017 analysis of 14 Cochrane reviews on studies of probiotics for GI disorders, Elizabeth Parker and associates found that the majority reported insufficient evidence to confirm benefit. This analysis also highlighted problematic inconsistencies, with many studies failing to specify the strain(s) in the probiotic and most not specifying any follow-up beyond the initial intervention.
In the consumer setting, Cohen noted that many companies do not follow FDA-recommended best practices for manufacturing dietary supplements, and commonly fail to establish the strength, purity, and composition of the final products, with some found to contain contaminants and unlisted live microorganisms. A 2017 inspection of 655 supplement facilities found sanitation and other violations in more than half. In one worst-case example, the death of an 8-day-old premature infant from fulminant
gastrointestinal mucormycosis was traced to fungal contamination from a mold in a probiotic supplement.
Cohen argued for a consistent regulatory framework to ensure safe marketing of all probiotic-type microorganisms: “High-quality microorganisms with a long track record of safety should be accurately labeled and readily available to consumers, and labels should only advertise health claims if robust clinical evidence has demonstrated efficacy.”
Such a framework would, however, require new laws, and Cohen said he held out small hope that Congress would take steps to regulate probiotics in the near future. The FDA recently released a
draft guidance encouraging probiotic manufacturers to list the number of colony-forming units in the Supplement Facts labeling. But that is not enough, he said, praising the Canadian approach, which requires manufacturers to list the specific strain or strains and the number of live microorganisms per serving on every supplement bottle.
“The FDA should also revise its current good manufacturing practices for live microorganisms and include additional safety testing, such as identifying and eliminating potentially transferable antibiotic resistance genes, for all bacterial strains prior to marketing, as is currently required in Canada,” Cohen wrote. In the meantime inadequate regulation and poor compliance “remain substantial problems.”
Last Updated September 18, 2018
Cohen reported relationships with NSF International and Consumers Union.
Hou reported having no competing interests related to his comments.
Primary Source
JAMA Internal Medicine
