Infant Fecal pH Revealed as a Critical Indicator of Infant Gut Health and Resistance against Gut Pathogen Invasion

DAVIS, Calif., April 9, 2020 /PRNewswire/ -- Fecal pH has long served as a critical indicator of gut health and is widely considered one of the best differential diagnoses of digestive disorders and the presence of bacterial pathogens. However, a new feature paper published by researchers at Evolve BioSystems in the peer reviewed journal High-Throughput demonstrates that the previously established fecal pH reference range provided an inaccurate view of a baby's gut health, masking the risk of overabundance of pathogenic gut bacteria during a critical period of immune system development. This new publication provides the scientific rationale for the updated infant fecal pH reference range now adopted by a leading national testing laboratory.

The new paper demonstrates that the previously established fecal pH reference range – which applied to all age groups and fell between pH 7.0-7.5, did not properly reflect the pH levels required for protection from harmful gut pathogens in infants. Importantly, the paper also shows that the substantially lower pH levels are associated with the presence of Bifidobacterium longum subsp. infantis (B. infantis), protection against intestinal inflammation, and defense against pathogenic bacteria that are known to derail proper immune development in infants.

The paper, Colonization Resistance in the Infant Gut: The Role of B. infantis in Reducing pH and Preventing Pathogen Growth, is coauthored by Evolve BioSystems researchers Dr. David Kyle, PhD., Chief Scientific Officer; Dr. Rebbeca Duar, PhD., Senior Scientist, Microbiology; and Dr. Giorgio Casaburi, PhD., Principal Scientist, Bioinformatics and corresponding author.

"As many as 90 percent of infants born today have elevated fecal pH levels, which means they are deficient in critical gut bacteria and immediately at risk for pathogenic infections and compromised immune system development; yet, we were measuring that risk by the wrong standard," said Dr. Casaburi. "To truly maximize the benefit of using infant fecal pH as a tool, we must adopt a reference range for infants that accurately, objectively and uniquely reflects a healthy infant gut microbiome, the presence or absence of B. infantis, and the level of protection the baby is developing against harmful gut pathogens."

The paper documents the association between the presence of B. infantis, and its metabolic products lactate and acetate, with the healthy infant gut pH levels correlated with colonization resistance. The now established healthy reference range of pH 4.5 to 5.5 for infants 0-6 months is driven by the presence or absence of B. infantis in the infant gut, a key bacteria shown to lower colonic pH to a range that limits the growth of gut pathogens in infants. Importantly, the paper points to an activated strain of B. infantis that, when fed to infants, has now been clinically demonstrated to reduce fecal pH to the newly established healthy range.

A 2018 study^[i] published by Evolve documented a consistent and dramatic generational increase in the average pH of a baby's stool, a key indicator of infant gut health, and reported for the first time a significant inverse relationship between fecal Bifidobacterium abundance and fecal pH.  Researchers reported an alarming increase in infant gut pH from 5.0 in the early 20^th century to 6.5 by 2017. The rise in pH reflects a significant and growing deficiency in so-called "good gut bacteria" – notably B. infantis, which plays a critical role in protecting the infant from harmful pathogens including E. coli, Klebsiella and Clostridia, as well as supports the development of the immune system. Additionally, a recent study published in BMJ Paediatrics Open reported that elevated fecal pH was found to have a significant association with stunted growth in children.

"We are seeing an elevation of pathogenic bacteria in the gut microbiome of the newborn infant, a crisis we can begin to turn back by first committing to the appropriate tools to identify those infants at risk," said Dr. Kyle. "The key takeaway is that healthy adult fecal pH does not equate to healthy infant fecal pH, since the makeup of the healthy adult and infant microbiomes are completely different. Using an adult fecal pH reference range to define a healthy infant gut is like using the average temperature in Florida as a reference for 'normal' temperatures in Alaska."

About Evolve BioSystems, Inc.

Evolve BioSystems, Inc. is a privately held microbiome company dedicated to researching solutions to establish, restore, and maintain a healthy gut microbiome. Evolve is a portfolio company of the Bill & Melinda Gates Foundation and Horizons Ventures, the venture division of the Li Ka Shing Foundation. Evolve is a spin-off from the Foods for Health Institute (FFHI) at the University of California, Davis and builds on more than a decade of research into understanding the unique partnership of the infant gut microbiome and breast milk components.

[i] https://www.evolvebiosystems.com/news/2018/3/7/new-study-shows-significant-changes-to-infant-fecal-ph-over-last-100-years

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SOURCE Evolve BioSystems