From birth to beyond, bifidobacteria are lifelong friends
By: Gerrit Stuivenberg, PhD Candidate
Amid a pandemic it’s easy to lose sight of our tiny friends, beneficial microbes, due to the overcast caused by devastating pathogens. I can recall having several conversations, one with my mother, where the idea that some bacteria are good for humans, in this case for newborn babies, caused visible shock. With the recent explosion in the popularity of probiotics, it’s clear that unlike my mother, there has been an important cultural shift away from the school of thought that all bacteria are bad. Despite this progressive movement, it seems that a lot of new parents are still uncomfortable with giving bacterial supplements to something so delicate as an infant. Or in my mother’s case, discomfited by the mere mention of bacteria colonizing a newborn. It is my intention with this short blog post to both remind us of some of the ‘good guys’ found in the gut that provide body wide protection and to highlight their critical role in human health starting at birth. For those interested in a more comprehensive discussion and access to relevant references, please refer to my recently published formal review article on the topic (Stuivenberg et al. 2022).
Figure 1. Methods of enhancing bifidobacterial colonization in the infant gut.
It is believed that microorganisms from the mother interact with the baby both in the uterine environment and during birth. However, the bacteria acquired by the baby vary dramatically depending on the birthing method; C-section infants are less likely to be colonized by these advantageous bacteria from the mother’s vagina and intestinal tract compared to vaginal birth. As a result of this, there is a significant reduction of health associated bacteria, like Bifidobacterium, in these infants. Alternatively, vaginally born infants obtain these bifidobacteria that then establish themselves as core organisms in the gut of these newborns. Through their ability to utilize human milk oligosaccharides (present in breast milk), the mother’s milk not only nourishes the newborn but also allows that bifidobacteria to thrive in their bodies. Upon colonization, their health benefits are established by modulating immunological development, preventing deadly infection, and producing essential metabolites that yield other developmental benefits. Notably, this is reflected in the observation that the absence of these bacteria in newborns is associated with the onset of chronic disease later in life.
I want to draw attention to the fact that these bifidobacteria also represent a perfect example of the point I was trying to prove to my mother. Not only can bacteria be good for humans, but some may be critical for normal development and the prevention and/or treatment of disease!
So, is there a way to re-establish Bifidobacterium in the infants that lack them? The simple answer is yes, and probiotics are the most obvious method of doing so. But the road to get there is much more complex than that (Figure 1). With ethical and, in the case of my mom and others, moral issues surrounding the supplementation of live microorganisms to infants, such an intervention would require rigorous safety testing and proof of the strain’s necessity. Where we stand now, there is no clear picture as to which strain(s), if any, could be universally applicable to infants, though some have been proven to protect against conditions like necrotizing enterocolitis. While it has been suggested that a general increase of the genus Bifidobacterium would be useful, the desired health outcome of a probiotic strain specific. Ergo, there is a need for the development of probiotics based on clinical studies that prove strain efficacy and not based solely on what is present in a healthy infant. As our ability to predict the appropriateness of strains for probiotic application using methods like metabolomics and transcriptomics improves, I hope to see more studies aimed at bolstering infant health using probiotics.
Gerrit Stuivenberg, PhD Candidate in Microbiology and Immunology at Western University
While much less abundant, bifidobacteria continue to play an important role in human health later in life. Of particular interest to me right now is the association between reduced Bifidobacterium titers in the gut and several pathologies commonly diagnosed in adulthood, including kidney diseases. Despite there being great success in mitigating some of these conditions through the oral dosing of probiotic bifidobacteria, the reasons behind these outcomes are still unclear; my PhD thesis is focused on understanding these factors. My current aim is to understand how bifidobacteria influence kidney health in individuals with renal disease and kidney stones. My work has already led to the novel discovery that four Bifidobacterium strains can metabolize harmful uremic toxins that are deleterious to renal function. Since a strain can only perform tasks for which it has the genes, the discovery and characterization of these beneficial properties can lead to the development of probiotics with greater specificity and efficacy against the target disease.
Despite progress being made, there is still so much to discover about bifidobacteria. Indeed, I am excited to learn of other interesting properties harboured by this genus that will surely be discovered in the years to come. However, the usefulness of these properties to human health must be confirmed through well designed clinical studies. There is also a dire need to improve communication of these findings with physicians and the public. In doing so, I believe we can eliminate the confusion surrounding what strain to use for a particular ailment and reduce the anxieties that people like my mother may have over the consumption of live microorganisms. But I digress, I am extremely grateful to be a part of a research group at the forefront of this field and to be given the opportunity to share some of my thoughts. I hope that with time, everyone can come to appreciate the beauty of probiotics and the seemingly limitless possibilities of their application.
References:
Stuivenberg GA, Burton JP, Bron PA, and G Reid (2022). Why Are Bifidobacteria Important for Infants? Microorganisms10(2): 278. DOI: 10.3390/microorganisms10020278.