A study from UT Southwestern Medical Center has shown that Serotonin, the happy hormone, can lessen the likelihood of gastrointestinal infections and illness with 90% of the hormone now being shown to be produced in the gut.
Medical books will tell you that Serotonin is a chemical produced by nerve cells. It is a neurotransmitter enabling the passing of signals between nerve cells. It is found throughout the nervous system and also in the blood platelets of your immune system. The hormone is known to affect your mood and emotions, your immune system and also your motor skills. Serotonin is produced from an amino acid Tryptophan – you do not make tryptophan, you must consume it – it is typically found in red meat, nuts and cheese.
In the research (1), rodents were modified to over-produce serotonin and this affected and blocked genes that pathogens use t cause illness. A human equivalent pathogen would be E coli. There was much less illness caused by the pathogens in the high serotonin mice.
Modern thinking is that 90% of the hormone serotonin is actually produced in the gut by beneficial bacteria according to lead author Vanessa Sperandio.
Further research from other centres has shown that serotonin limits IBS, cardiovascular disease and osteoporosis amongst other diseases.
This is because a third type of cell (Enterochromaffin cells, or EC) can also produce serotonin, not just nerve cells and immune platelets.
A study (2) from Caltech (California Institute of Technology) showed that bacteria-free mice produced 60% less ‘peripheral’ serotonin, indicating that serotonin production was stimulated by bacteria in the gut.
Professor Hsiao and the team conducted further studies and showed spore forming bacteria could influence the production of serotonin by EC cells, but that some gut bacteria even made serotonin themselves. Serotonin plays a strong role in fighting depression which is why it has been dubbed the happy hormone.
Serotonin stimulating drugs have been used in the past before the gut connection was understood. Such antidepression drugs can be addictive, damaging and even kill. This is called Serotonin Syndrome (3). Nature seems now to have the answer.