Veiga study analysis: Can probiotics improve gut microbiota stability?

In this contribution, GMFH board member Mary Ellen Sanders analyzes one of our recent website selections:  Veiga et al. (2014) Changes of the human gut microbiome induced by a fermented milk product.

Probiotics are a promising means to manipulate the microbiome, but there is little evidence that they can do this by changing the microbiota composition. Yes, the genus or species of the probiotic are transiently increased, but there is little evidence that probiotics can reshape a microbial community.

Veiga et al. (2014) suggest that the lack of such evidence may be due to poor resolution of the phylogenetic tools used to date. Using updated methods, they detected species-level changes after feeding female IBS subjects yogurt containing Bifidobacterium animalis subsp. lactis, Lactococcus lactis, and the yogurt starter bacteria. The observed changes were increases of 4 unknown species (MGS126, MGS203, MGS106, MGS109) and Bifidobacterium dentium, and reductions of Parabacteroides distasonis, Bilophila wadsworthia (an opportunistic pathogen) and Clostridium sp. HGF_2 . In subjects consuming the acidified milk control product, Haemophilus parainfluenzae and a 5th unknown species (MGS204) were reduced. In addition, yogurt increased short chain fatty acids. Applying functional genomic tools, the metabolic pathways of the unknown species can be elucidated, providing insight into what roles these microbes might play.

This work shows that dietary microbes lead to microbiota changes in IBS subjects. The authors suggest that these changes may ameliorate symptoms through improved homeostasis of gut microbiota and their functions through cross feeding between ingested bacteria and resident ones.

The ability of dietary microbes to promote stability of the gut microbial communities is an intriguing hypothesis. Although the ideal composition of a healthy gut microbial community is not known, a reasonable argument could be made that a useful characteristic of a probiotic in a healthy person is to maintain microbiota stability – either through promotion of resilience so that a potential perturbation has less of an effect, or through facilitating a return of a perturbed microbial community to normal. Such a homeostatic function could also be brought to bear after correction of some deficiency in a microbial community (as occurs with fecal microbial transplant or other microbial interventions), with the aim of promoting stability of the newly established, healthier community.

The Veiga et al. (2014) paper proves that one probiotic yogurt can impact the gut microbial community; additional studies targeting the promotion of stability of gut microbial communities through ingestion of probiotic yogurt would be of great interest.

Mary Ellen Sanders
Mary Ellen Sanders
Mary Ellen Sanders is a consultant in the area of probiotic microbiology, with special expertise on paths to scientific substantiation of probiotic product label claims. Dr. Sanders served as the founding president of the International Scientific Association for Probiotics and Prebiotics (ISAPP) and is currently the organization’s Director of Scientific Affairs/ Executive Officer. This international, non-profit association of academic and industrial scientists is dedicated to advancing the science of probiotics and prebiotics (www.isapp.net). Through numerous written, oral and video pieces, including a website, www.usprobiotics.org, she strives to provide objective, evidence-based information on probiotics for consumers and professionals. Key activities include: Panels to determine GRAS status of probiotic strains ; member of the American Gastroenterological Association Scientific Advisory Board for AGA Center for Gut Microbiome Research and Education ; World Gastroenterology Organisation Committee preparing practice guidelines for the use of probiotics and prebiotics for GI indications (2008, 2011, 2014) ; working group convened by the FAO/WHO that developed guidelines for probiotics (2002).