While conducting fieldwork in the highlands of Papua New Guinea, Professor Masahiro Umezaki of the Graduate School of Medicine noticed that the highland inhabitants whose diet consisted of sweet potatoes as the staple food had a well-developed musculature despite their low intake of protein.
Upon analyzing stool samples he had collected from the highland people, Umezaki discovered a key nitrogen-fixing gut bacteria, which could shed light on the symbiotic relationship between humanity and gut microbiota.
Some of the proteins that form muscles may be derived from nitrogen in the atmosphere. Although humans are unable to use inorganic nitrogen in the air, bacteria can convert the nitrogen into ammonia. Some bacteria use the ammonia to synthesize amino acids, which humans can absorb and use. Thus, the gut bacteria of Papua New Guinea highlanders could be thought to fix nitrogen and convert waste products into amino acids, which are used to form muscles. Although experiments on animals transplanted with fecal microbiota have provided interesting outcomes, it remains to be seen whether there is any association with muscle synthesis in humans.
