The happy hormone (serotonin) and how to boost it

What is serotonin?

The happy hormone, serotonin [5-hydroxytryptamine (5-HT)] is known to play a role in keeping normal developmental, cardiovascular, gastrointestinal, and endocrine function.

A large proportion of serotonin (in mammals) is found in the gut. However, the role of serotonin in specific brain regions is often what intrigues us – modulation of mood states, sex, sleep, emotion, anxiety, endocrine effects, aggression, appetite, mood, cognition, and memory are just some of the important roles that serotonin plays in normal brain function.

Biosynthesis of serotonin

In mammals serotonin is biosynthesised in a two-step process:

Firstly, the enzyme tryptophan hydroxylase catalyses the ring hydroxylation of the essential amino acid tryptophan in the rate-limiting step. Lastly, side chain decarboxylation is catalysed by an aromatic amino acid decarboxylase enzyme.

How to boost the happy hormone?

  1. Boost your tryptophan through your diet (it is an essential amino acid – one the body cannot synthesise); foods rich in this amino acid include: chicken, eggs, cheese, fish, peanuts, pumpkin and sesame seeds, milk, turkey and bananas.
  2. Increase exercise levels – brain tryptophan concentrations and serotonin synthesis and release increase during running.
  3. Increase probiotics – probiotics in the GI tract have been shown to affect levels of serotonin via the gut-brain axis.
  4. Increase Vitamin D (diet or sun) – Vitamin D regulates TPH2 (in brain) and TPH1 (in gut), in serotonin synthesis pathways.


Nichols, D. E., & Nichols, C. D. (2008). Serotonin receptors. Chemical reviews108(5), 1614–1641.