New Approaches Targeting the Microbiome in CV Disease Sue Hughes April 25, 2019 published online in the April 30 issue of the Journal of the American College of Cardiology. Detailed mechanistic studies have strongly implicated the key role of the gut microbiome in mediating cardiovascular disease processes or risk factors, but most previous studies have focused on characterizing the microbial composition rather than its functional alterations and downstream consequences, the review states. "While previous studies have focused on what specific organisms are implicated, we are beginning to realize that it is their balance of the ecosystem within the body that creates an environment that protects or promotes various cardiovascular diseases," lead author W.H. Wilson Tang, MD, of the Cleveland Clinic in Ohio, told Medscape Medical News. "Therefore, a more holistic concept has evolved based on how gut bacteria can generate metabolites from the nutrients ingested and how these may affect different human organs," Tang said. Tang explained that prior studies have hypothesized that specific bacteria may directly promote pathophysiologic processes, and that by eliminating them with antibiotics, might lead to fewer adverse events. "This approach has not worked because the underlying mechanisms were poorly understood, and there is an assumption of 'one-size-fits-all,' " Tang said. "Now we appreciate that much of our gut bacteria are likely beneficial and their compositions in our healthy gut are often difficult to alter, yet their metabolism can be modulated by dietary exposures that are unique across individuals." The review notes that in the latest studies, researchers have identified new mechanisms that can explain why some gut bacteria metabolites from dietary nutrients can be potentially beneficial (such as short-chain fatty acids modulating blood pressure) while others may be potentially harmful, such as trimethylamine N-oxide (TMAO) that can affect cholesterol metabolism, promote atherosclerosis, and increase thrombosis risks. Conflicting Results Tang reported that, thus far, studies on the effects of various different diets on the microbiome have produced conflicting results. "What is clear is that dietary patterns represent one of the biggest environmental exposures to our gut bacteria, and so altering diet may indeed play some role in reshaping our gut microbial metabolism and overall health. However, the concept of classifying food groups or diets as 'good' or 'bad' for health is somewhat outdated, since it depends largely on how nutrients are digested and interact with the body's gut bacteria," he said.
