Probiotics Raise Concerns in Vulnerable Populations

Giuliana Miranda

May 25, 2023

In a study published in the journal Gut Microbes , specialists affiliated with the International Scientific Association for Probiotics and Prebiotics (ISAPP) raised questions regarding the safety of probiotics, especially among vulnerable populations (such as newborns, pregnant women, patients with short bowel syndrome, and patients who are immunocompromised). Despite theoretical and proven adverse events from probiotic consumption, according to the authors, research is needed to address gaps. Areas for future study include the possibility of antibiotic resistance gene transfer via transformation, the potential impact of probiotic‑induced changes in microbiomes, and interactions with drugs.

Probiotics, guidelines for which were published by the Food and Agriculture Organization of the United Nations and the World Health Organization in 2001, are currently defined as "live microorganisms which when administered in adequate amount confer a health benefit on the host." However, as the first probiotics were associated with naturally fermented foods (yogurts, for example) and not seen as medications, their potential side effects were not often monitored, and their use was not regulated. Over the past 12 years, however, clinical studies have been looking into possible complications associated with the use of these microorganisms.

Long-term studies designed to demonstrate probiotic safety in populations at risk are scarce. This situation, as well as the expanding use of probiotics in vulnerable patients, requires concise and actionable recommendations on how to work toward the safe and effective use of probiotics. The ISAPP convened a meeting to discuss and produce evidence-based recommendations on potential acute and long-term risks, risks to vulnerable populations, the importance for probiotic product quality to match the needs of vulnerable populations, and the need for adverse event reporting related to probiotic use.

Genomic Sequencing Essential

Researchers concluded that a foundation for assessing the safety of any probiotic strain is a complete genome sequence, which should be conducted before incorporating new species into food and supplement manufacturing processes.

"This allows assignment of the strain to a given taxonomic group, enabling review of published risks associated with the species. A full genome sequence also allows strain-level identification, which can be important for tracking the strain during production and to investigate etiology of suspected infections. Further, the genome can be interrogated for any genes of concern, including toxigenicity, pathogenicity, or antibiotic resistance," the article emphasizes.

Scientists have been concerned with the possibility of transferring resistance genes to intestinal microbiota for several years. In a study published in 2022, Alexander Crits-Christoph, PhD, and colleagues affirmed that advances in metagenomic sequencing can help prevent the use of new probiotics that could contribute to antibiotic resistance in patients.

Essential Care

Issues related to the safe formulation of probiotic products include the need to establish the purity, potency (that is, the quantity of live microbes delivered), and composition of the final product. Furthermore, probiotic products must undergo adequate testing — adapted to the intended use — for potential contaminants. "Since probiotics are designed to be administered as live microbes, contamination with pathogenic or potentially pathogenic microbes is a greater risk than for products that undergo an intentional sterilization process," write the authors.

Correctly handling and administering probiotics is also essential. Before prescribing probiotics, the clinician must consider the patient's health condition and potential risks.

The Probiotics in Pancreatitis Trial (PROPATRIA) raised one example of potential risk. This study's results suggest that the enteral use of some probiotic preparations could be contraindicated in patients with severe health conditions.

The specialists from the ISAPP concluded that more studies are needed on the long-term effects of probiotics, particularly in more vulnerable groups, and rigor in collecting and reporting data on adverse events is required.

Although the specialists confirm the need for understanding the entire genetic makeup of a probiotic as a cornerstone for assessing its safety, long-term safety assessments for probiotics should be consistent with and not more stringent than current regulatory requirements for biologic drugs, including fecal microbial transplants.

This article was translated from the Medscape Portuguese Edition.


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