Longevity Briefs: Could A Healthy Gut Microbiome Stave Off Heart Disease?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: The bacteria in our gut have a large and often overlooked impact on our health. As we grow older, the gut microbiome tends to change for the worse, with the bacteria producing beneficial molecules declining in numbers, while populations of bacteria contributing to inflammation become more numerous. The human gut is home to hundreds of different species of bacteria, but genome sequencing technology has made it possible for scientists to collect detailed data about the composition of the microbiome, and look for correlations with the progression of the ageing process.

What did the researchers do: In a small study, researchers studied the cardiac health and gut health of 15 participants with an average age of 75. They used echocardiography (a type of ultrasound scan) to measure left ventricular relaxation speed, which is related to cardiac ageing in older adults (slower relaxation is a sign of ageing). They then sequenced the genomes of the bacteria in participants’ guts and studied whether there was any association between the species of bacteria present and signs of cardiac ageing.

Key takeaway(s) from this research: 8 participants had signs of cardiac ageing according to the researchers’ metrics, and their guts contained higher levels of several harmful bacterial species. These included Ruminococcus species, which produce an inflammatory molecule called C-reactive protein, and of which certain species are also known to produce TMA, a molecule that has been linked to atherosclerosis and heart disease. Paraprevotella species were also more abundant. These bacteria produce inflammatory molecules and are associated with heart failure in mice.

Participants without cardiac ageing were found to have higher levels of Firmicutes bacteria, which are producers of short chain fatty acids that regulate cholesterol. Some species have been associated with higher levels of ‘good cholesterol’ (HDL), and previous research has suggested that rats with fewer Firmicutes bacteria get more heart failure.

This study was small and doesn’t prove that the changes in microbiome composition caused more rapid cardiac ageing. However, the results line up with what we already know about these bacterial species, and support previous studies suggesting that the ratio of such species in the gut could be an important marker of ageing. We’ll need larger studies to confirm these findings, and eventually to investigate whether interventions to rebalance the gut microbiome (such as faecal microbiota transplants) can help reduce the risk of heart disease, as has already been shown in some animal models.