Researcher Dr. Michael Lustgarten has recently published a compact and very readable review that focuses on the role of the gut microbiome and its influence on skeletal muscle mass.

The gut microbiome

The microbiome describes a varied community of bacteria, archaea, eukarya, and viruses that inhabit our gut. The four bacterial phyla of Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria comprise 98% of the intestinal microbiome.