Vascular diseases including stroke and infarctions will kill 20 million people in 2015, according to the World Health Organization. Such a catastrophic number obliges scientists to explore the links between microbial dysbiosis and cardiovascular impairment, associations only discovered in the last decade or so.
The theories and conflicting data are nicely reviewed by Matteo Serino and colleagues from Toulouse, France in an Open Access article available here.
The study of gut microbiota has raced past the act of growing bacteria in petri dishes to the high-tech molecular sequencing which gives a much more detailed snapshot—phyla to species—of an organism.
Dysbiosis has been traced to allergies, diabetes and obesity as well as other metabolic disturbances.
What are the clues that dysbiosis could contribute to cardiac problems?
- Certain microbes metabolize dietary byproducts of protein metabolism (choline and L-carnitine) to atherogenic substances.
- After vancomycin antibiotic treatment, microbial changes corresponded with a reduction of infarcts as well as reduced leptin—a hormone which suppresses appetite.
- Gut microbes put in disarray by diet or medications may cause bacteria to infest blood which can encourage plaque formation. Plaque narrows blood vessels and can chip off to cause blockages. Plaque is largely made up of Proteobacteria, a phylum also implicated in the blood of diabetics.
The plot thickens. Bacteria from the oral cavity may also instigate cardiovascular diseases. Migration of infective agents from the mouth into the bloodstream can trigger endocarditis and infarctions.
As evidence mounts in the role of microbes in cardiovascular diseases, it is prudent to step back and see that association does not prove guilt. Disease and its consequences may be causing these complex microbial changes. Or the opposite may be true.