Serotonin is the famous neurotransmitter oft attributed to causing joyous type emotions. Unlike most neurotransmitters, which are produced predominately in the brain and nervous system, a recent study mentioned in a review article estimate that, “90 percent of the body’s serotonin is made in the digestive tract. […] [C]ertain bacteria in the gut are important for the production of peripheral serotonin.”
Interesting play on words of the “Microbiome.” The gut microbiome comprises most of our body but very little of our mass… It outnumbers our cells 10 to 1! [Source]
Researchers at the California Institute of Technology (Caltech) sought to identify a link between the gut microbiome and the production of the serotonin neurotransmitter. Peripherally made serotonin is already understood as a product of the digestive tract, however, is there a link between the myriad of bacteria that compose our gut microbiomes and the neurotransmitter? What they found, was surprising; notwithstanding the known communicative link between the nervous system and the microbiome, the researchers found that the microbiome is not directly responsible for most of the production of the neurotransmitter. The bacteria interact and stimulate the production of serotonin by the intestinal cells.
To arrive at this conclusion, the researchers studied the effects of “germ-free” mice. They found that the mice that exhibited a dearth of flora within. Experimental results indicated that the mice produced around 60% less serotonin than mice with normal gut microbiomes. The experiments also demonstrated an interesting result that may lead to future studies on the serotonin deficiency treatments–the researchers found that when augmenting the gut microbiomes with bacteria responsible with serotonin production stimulation, the levels of the neurotransmitter increased. Of course, the subject is vastly complicated, and will therefore require extensive research to more fully understand.