Why We Are Not Making Progress with Probiotics

A recent commentary A Khoruts et al. Gastroenterol 2020; 159: 409-413. Full text: Probiotics: Promise, Evidence, and Hope

Despite the fact that the probiotic industry has ample money which is projected to reach $70 billion yearly, there is very little high quality research.

Key points:

  • Probiotics are regulated by the Food and Drug Administration (FDA) and the Federal Trade Commission (FTC). The FDA, unlike the FTC, regulates products by category (eg, foods, drugs, dietary supplements, medical devices, and cosmetics)…Foods and dietary supplements, unlike drugs, do not require FDA premarket approval. By law, probiotic foods and dietary supplements must be safe. However, food manufacturers are permitted to make a self-determination of whether their product meets the “generally recognized as safe” (GRAS) designation, typically based on history of prior use”
  • Probiotic food and dietary supplement manufacturers do not have to specify on their product labels the strains they use in probiotic products or specify the number of live microbes of each strain that the product delivers through the end of its shelf life; and, although they are required to have validation of label claims, they are not required to submit it to the FDA
  • Dietary supplements can make structure/function claims, even though they cannot claim to treat any specific disease. These claims can sound very promising and consumers may be hard pressed to distinguish between a statement that a product “improves digestion,” a structure/function claim that is so vague that it is literally untestable
  • Rational selection of donor microbiota should be possible based on microbiome-based diagnostics, as well as in vitro technologies that interrogate the functional potential of complex microbial communities. There are parallel, intensive efforts to develop defined microbial communities. A common theme among these different approaches is deployment of complex assemblages of microorganisms rather than single strains. Such complex consortia are likely to have more consistent and predictable effects.
  • The emergence of microbial therapeutics requires development of a new branch of pharmacology. The challenges of formulation, pharmacokinetics, and pharmacodynamics are very distinct from those of small molecule therapeutics or protein biologics.

My take: “These next-generation probiotics will need to be tested for safety and efficacy in well-designed and properly powered clinical trials.”  Probably the only way that will happen is to empower regulatory agencies to insist that these products are treated like medications.  Given the fact that probiotics are so profitable now with little evidence of efficacy for most strains, I am not optimistic about any changes in the near future.

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