The beauty of the microbiome is that there are always new published studies that either reveal how its composition changes, and how those changes in microbiome composition make the difference between good health and bad.
Your digestive tract isn’t only for transforming your food and breaking down any medications you take. Long ago, Hippocrates declared that all disease begins in the gut.
The Aging Factor
Research has shown that aging affects the gut microbiome composition and activity. A new study investigated the impacts of aging on changes to the small bowel.
Researchers at Cedars-Sinai have found that aging produces significant changes in the microbiome of the human small intestine that are independent from those caused by medications or illness burden. Lead author Ruchi Mathur, MD, commented that by focusing on the microbial changes in the small bowel during aging, presence of illness and medication use, he hopes “to identify unique components of the microbial community to target for therapeutics and interventions that could promote healthy aging.
A unique angle to this study is how the team is focusing on gut inhabitants and their neighbors in the microbiome. Much of the prior research in this area has used stool samples, which do not reflect the entire gut microbiome; this study obtained and used samples from various points in the small intestine, which is more than 20 feet long and has the surface area of a tennis court. As such, stated Mathur, this groundbreaking microbiome research is the first study of its kind to examine the microbial composition of the small intestine of adults 18 years of age to 80. “
We now know that certain microbial populations are influenced more by medications, while others are more affected by certain diseases. We have identified specific microbes that appear to be only influenced by the chronological age of the person.” He and his team thus identified bacteria in the small bowel – called coliforms – that they dubbed "disruptors" which increase and exert negative influence on the gut microbial population. Additionally, they found that as humans age, the small intestine bacteria change through using less oxygen.
This research is part of Cedars-Sinai's ongoing REIMAGINE study (“Revealing the Entire Intestinal Microbiota and its Associations with the Genetic, Immunologic, and Neuroendocrine Ecosystem”).
Similarly, a research team recently analyzed gut microbiomes and clinical data from over 900 elderly individuals aged of 78-98 years old from a larger cohort of approximately 9000 adults.
The data showed that gut microbiomes became increasingly divergent from others as individuals aged, starting in mid-to-late adulthood, which corresponded with a steady decline in the abundance of core bacterial genera, Bacteroides.
The researchers observed that while microbiomes became increasingly unique to each individual in healthy aging, several metabolic functions of the microbiomes shared common traits. This gut uniqueness signature was more clearly associated with several microbially derived metabolites in blood, including one -- tryptophan-derived indole -- that has previously been shown to extend lifespan in mice. They also saw that phenylacetylglutamine (another metabolite in the gut microbiome) is highly elevated in the blood of centenarians.
"This uniqueness signature can predict patient survival in the latest decades of life," said lead author Tomasz Wilmanski, MPH, PhD. “This uniqueness pattern appears to start in mid-life -- 40-50 years old -- and is associated with a clear blood metabolomic signature, suggesting that these microbiome changes may not simply be diagnostic of healthy aging, but that they may also contribute directly to health as we age," Wilmanski said. For example, indoles are known to reduce inflammation in the gut, and chronic inflammation is thought to be a major driver in the progression of aging-related illnesses.
According to the researchers, this investigation is the first to show two clear aging trajectories in which the microbiome has a role: a decline in core microbes and an accompanying rise in uniqueness in healthier individuals, and the maintenance of core microbes in less healthy adults. They concluded that “this analysis highlights the fact that the adult gut microbiome continues to develop with advanced age in healthy individuals, but not in unhealthy ones, and that microbiome compositions associated with health in early-to-mid adulthood may not be compatible with health in late adulthood.”
The Winter Protection Factor
Because of the pandemic, researchers have been diving into studies that investigate how humans can be better self-protected against contracting an infectious compound as well as protection against spreading it. Several teams have decided to focus on how the microbiome is affected by and affects incoming viruses, which tend to become highly active in the cold weather months.
According to authors of a new study, researchers are “gaining a better understanding of the internal factors associated with viral immunity. Increasingly the gastrointestinal microbiome has been shown to be a significant player in the host immune system, acting as a key regulator of immunity and host defense mechanisms. An increasing body of evidence indicates that disruption of the homeostasis between the GI microbiome and the host immune system can adversely impact viral immunity.”
Their review investigated previous evidence linking how the human commensal organisms (microbiota) and microbiome therapeutics can impact and modulate viral expressions in cases of specific virus expressions (such as gastroenteritis, upper respiratory tract infections and others). They concluded that while the interrelationships between the GI microbiome and invasive viruses are exceedingly complex, there is increasing evidence that the microbiome can have a powerful and specific impact on viral outcomes.
A review and opinion published earlier this year made a case for microbiome-based therapies to be developed for reducing viral loads. The author, Dr. Faizan A. Sadiq, observed what he characterized as a dire need to find new strategies to improve clinical practices related to viral infections. He explains, “Today, it is difficult to find any prominent viral infection that hasn't had any link with the human gut microbiota. In this opinion-based review article, I argued the significance of manipulating human gut microbiota as novel therapeutics through probiotics in alleviating complexities related to viral infections, and pinpointed bottlenecks involved in this research.”
In her scientific article appearing for the International Probiotics Association, Clare Fleishman MS, RDN, writes, “Use of probiotics to manipulate the microbiota to defend against or manage viral infections is well-worth exploring.”
It is becoming more apparent that the microbiome has significant impact on an individual’s overall health and well-being. The world of probiotic (and prebiotic and synbiotic) products can help anyone begin to renovate their health for the short- and long-term by providing the right residents in the gut.