Is your gut health making you sad, depressed and difficulty falling sleep ??
Serotonin (5-hydroxytryptamine or 5-HT) is a neurotransmitter well known for its ability to promote feelings of happiness and wellbeing. However, serotonin can also play significant roles within the gastrointestinal tract, pancreas, liver and bones.
The vast majority of the body’s serotonin (approx. 90%) is produced and stored in the gut by enterochromaffin (EC) cells located in the gastrointestinal epithelial layer,with the second major pool of serotonin produced in the brain (approx. 5%)
Interestingly, a recent paper detailing a mouse study by Kumar et al. 20209, highlights yet another potential purpose for serotonin.
The paper found that serotonin could decrease the gene expression of certain virulence factors produced by pathogenic species such as Escherichia coli.
Essentially, this means serotonin blocks pathogens from invading colon tissue and causing infection.
The amount of pathogen gene suppression that occurred in this study was also relative to the amount of serotonin present. When serotonin levels were decreased in the gut, there was an increased chance the pathogen would infect, whereas when serotonin levels increased, the pathogen’s potential to invade cells was reduced.
The authors also demonstrated that gut bacteria can directly influence serotonin production in the colon lumen.
How diet can support serotonin
Tryptophan is the only precursor for both centrally and peripherally made serotonin.It is one of the nine essential amino acids which means the body cannot synthesise tryptophan on its own and therefore, it must be obtained through diet.
-Oats, bananas, milk, tuna, cheese, bread, poultry and peanuts are common foods that contain tryptophan.
Serotonin synthesis from tryptophan also requires nutrients, such as vitamin B6 (pyridoxine), vitamin B3 (niacin), and glutathione (an antioxidant predominantly produced by the body).
Increasing the consumption of fermentable prebiotic fibres commonly found in an array of plant foods will support the growth of specialised microbial species in the gut. These species can increase SCFA production which will ultimately help stimulate EC cells and thereby support serotonin production.
This highlights the benefits of having good diet to help healthy stores of gut bacteria to support serotonin and which is WHY I request functional testing on the microbiome for a wholistic mental health approach.