An aging gut microbiome has been linked with heart diseaseBy Connie Wan, P.h.D | May 13th, 2019
A recent study, led by scientists from the University of Colorado Boulder (UCB), suggests an aging gut microbiome may be responsible for the degradation in cardiovascular heath as we grow older. The study is another addition to the growing body of evidenceaffirming the role gut bacteria plays in age-related disease.
Age-related cardiovascular disease is primarily driven by stress-mediated arterial dysfunction. We know that as a human body grows older the risk of cardiovascular disease increases. A striking 70 percent of all people in the United States between the ages of 60 and 79 suffer from some form of cardiovascular disease.
Inspired by the accumulating research pointing to the gut microbiome as a primary modulator of oxidative stress and inflammation, the UCB study looked at whether there was a direct connection between gut bacteria alterations and arterial dysfunction. To examine this, scientists used antibiotics to eliminate the microbiome of both old and young mice. After a few weeks of broad-spectrum antibiotic treatment, the young mice displayed no changes to their arterial health, however, the older mice showed major improvements across several vascular health measures. This suggests that the microorganisms in the aging mice may be responsible for vascular dysfunction.
As we age, the variety of bacteria in our microbiome diminishes. This lack of microbial diversity can result in an imbalance, called dysbiosis, which some hypothesize as the cause of many age-related diseases. To try to home in on how certain bacteria could be driving cardiovascular disease, the researchers analyzed the differences between the old and young animals’ microbiome. In the old mice, the researchers saw an increased prevalence of microbes that are pro-inflammatory and have been previously associated with diseases.
Significantly, one particular metabolite appeared in much higher levels in the old mice compared to the younger mice. Trimethylamine N-oxide, or TMAO, is a metabolite that has been strongly linked to atherosclerosis and stroke, and high levels of TMAO can appear in a person’s blood when large volumes of certain bacteria are present in the gut.
Scientists have long known that oxidative stress and inflammation are involved in making arteries unhealthy over time. It is hypothesized that, with age, the gut microbiota begins producing toxic molecules, including TMAO, which get into the blood stream, cause inflammation and oxidative stress and damage tissue.
It’s too early to jump to any conclusions as to what all this research ultimately means. The researchers suggest that maintaining a diverse microbiome in older age may be a beneficial way to reduce cardiovascular disease risk. This, of course, is not as simple as eating a particular probiotic, but the researchers are currently investigating the impact of different diets on gut health and cardiovascular disease in human subjects.
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Brunt V.E., et al., Suppression of the gut microbiome ameliorates age‐related arterial dysfunction and oxidative stress in mice, The Journal of Physiology, 04 February 2019, https://doi.org/10.1113/JP277336