Young Microbiome Associated with Healthy Hearts in Old Age

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Age-related changes to the gut microbiome contribute to vascular decline, a new study published in the Journal of Physiology has shown.

The research, conducted in lab mice, could lead to new interventions to prevent cardiovascular disease, a group of disorders that include coronary heart disease, peripheral arterial disease and congenital heart disease.

Seventy percent of Americans ages 60-79 have cardiovascular disease. By age 80, that number rises to 80 percent, according to statistics from the American Heart Association.

The University of Colorado Boulder-based research team assessed the cardiac function of young and old laboratory mice that had been given broad-spectrum antibiotics that killed the majority of bacteria living in their gut.

The health of the vascular endothelium (the inner lining of blood vessels), the stiffness of large arteries and the levels of inflammatory compounds, tissue-damaging free-radicals, antioxidants and the blood-vessel-expanding compound nitric oxide were evaluated in both groups of animals.

After four weeks of treatment with the antibiotics, the old mice showed improvements in all of the factors evaluated. There was no change in the vascular health of the young mice.

This suggested to the researchers that something in the microbiome of the aging mice was leading to cardiac dysfunction.

To learn more, the researchers genetically sequenced fecal samples of a different population of young and old mice, comparing the results between the two groups.

The samples of the older mice had higher levels of microbes that were pro-inflammatory, including Proteobacteria, a phyla that includes Salmonella and other pathogens, and pro-inflammatory Desulfovibrio.

Additionally, the metabolites—small molecules produced by gut microorganisms—had three as much TMAO (trimethylamine N-oxide) as the younger mice. TMAO has been linked to an increased risk of atherosclerosis, heart attack and stroke.

"We want to stress that we used antibiotics in this study as a mechanistic tool. We are not suggesting that people should take antibiotics, as there are many issues associated with their long-term use," Vienna Brunt, lead author and a postdoctoral researcher in the Department of Integrative Physiology, cautioned to Laboratory Equipment.

However, a diet high in probiotics or prebiotics could be used to help prevent heart disease in old age by keeping the microbiome healthy.

"We believe our results identify a role of the gut microbiome in artery dysfunction with aging and the eventual development of cardiovascular diseases. This means that promoting gut microbiome health should be considered along with other things we do to stay healthy as we age," Brunt said. "We hope that our research will support the development of new dietary interventions and/or supplements to support gut health with aging, as well as further research into the effectiveness of existing supplements like probiotics."

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