What is already known on this topic
Previous studies have shown that people with chronic heart disease have an altered gut microbiota. However, these findings may be confounded by several factors, such as the use of medications that can modify the composition of the gut microbiota.
What this research adds
Researchers analyzed the gut microbiota and the blood levels of bacterial-derived compounds in hundreds of people, including healthy individuals, people with obesity and type 2 diabetes but without a diagnosis of heart disease, and those who had heart conditions. They found that alterations of the gut microbiota are already present in people with obesity and type 2 diabetes, long before the onset of heart disease symptoms. People with heart disease showed specific alterations, including fewer types of bacteria producing beneficial molecules and more bacteria producing unhealthy compounds.
Conclusions
The findings uncover the gut microbiota changes that happen in the very early stages of heart disease. The microbial and metabolic profiles identified could be used as markers of the transition towards heart disease.
Coronary artery disease can lead to heart failure and is a major cause of mortality worldwide. Now, researchers have found that major alterations occur in the gut microbiota of people with heart conditions much before the onset of disease symptoms.
The findings, published in Nature Medicine, uncover the gut microbiota changes that happen in the very early stages of heart disease. The microbial and metabolic profiles identified could be used as markers of the transition towards heart disease.
Previous studies have shown that people with chronic heart disease have an altered gut microbiota, but these findings may be confounded by several factors, such as the use of medications that can modify the composition of the gut microbiota.
To investigate the role of gut microbes in cardiometabolic disease, two international teams of researchers analyzed the gut microbiota and the blood levels of bacterial-derived compounds in hundreds of people, including healthy people from Denmark, Germany, France and Israel.
Longstanding changes
In one study, researchers recruited 372 people with different stages of heart disease —angina pectoris, myocardial infarction or heart failure, as well as 275 healthy people and 222 people with obesity and type 2 diabetes but without a diagnosis of heart disease. The researchers characterized the participants’ gut microbes as well as the metabolites found in their blood and urine.
In another study, researchers analyzed the gut microbiota of 997 healthy people and 199 individuals with acute coronary syndrome — a range of conditions in which blood flow to the heart is suddenly reduced.
Both studies found that alterations of the gut microbiota are already present in people with obesity and type 2 diabetes, long before the onset of heart disease symptoms. People with heart disease showed specific alterations, including fewer types of bacteria producing beneficial molecules such as short-chain fatty acids and more bacteria producing unhealthy compounds.
Microbial profiles
In one of the studies, the researchers discovered a new bacterial species of the family Clostridiaceae whose levels were reduced in people with acute coronary syndrome. They also found that the metabolic profiles of people with the condition correlate with the individuals’ clinical parameters.
The other study found that drugs impacted about half of 700 bacterial species and 1,000 blood compounds synthesized by gut bacteria, but these disruptions did not increase the risk of heart disease. “Among the remaining half, about 75 percent of the disturbances of the gut microbiome occurred in the early disease stages of overweight and type 2 diabetes, many years before patients noticed any symptoms of heart disease,” says study senior author Oluf Pedersen at the University of Copenhagen.
Although the studies identified associations, rather than causal explanations, for the microbiota changes observed in people with cardiometabolic conditions, their findings provide insights into the microbial and metabolic profiles at different stages of disease. These may become targets of future preclinical trials of coronary artery disease, the researchers say.
“Intervention in both humans and rodents have shown that an imbalanced gut microbiome at various stages of heart disease development can be modified and partly restored by eating a more plant-based and energy-controlled diet, avoidance of smoking and compliance with daily exercise,” Pedersen says. “It is time for translating the accumulated evidence of the role of the gut microbiome to more focused public health initiatives in attempts to prevent or delay morbidity and mortality related to heart disease.”
