History
In the 1930s Italian pharmacologist Vittorio Erspamer found a substance in the gut lining that made intestines contract and called it "enteramine." In 1948 Maurice Rapport, Arda Green and Irvine Page at the Cleveland Clinic isolated a compound from blood serum that tightened blood vessels and named it serotonin, from serum and tonic. In 1952 the two were shown to be the same molecule, and a year later Betty Twarog found serotonin in the mammalian brain, launching its study as a neurotransmitter.
What it does
About 90% of the body's serotonin is made by enterochromaffin cells in the gut, where it controls gut motility and the vomiting reflex, and platelets carry it to help blood clot. Brain serotonin, made in the raphe nuclei of the brainstem, shapes mood, anxiety, impulsivity, appetite and pain; at night the pineal gland turns it into melatonin, tying it to sleep and circadian rhythms. Gut serotonin can't cross the blood-brain barrier, so the claim that "your gut makes your happy chemical" is only half right.
Antidepressants and the debate
Starting with fluoxetine (Prozac), approved by the FDA in 1987, selective serotonin reuptake inhibitors became standard treatment for depression and panic disorder. In 2022, however, an umbrella review led by Joanna Moncrieff found no consistent evidence that depressed people have low serotonin, sparking fierce debate. Many experts agree the "chemical imbalance" story was oversimplified but note that it's a separate question whether SSRIs help some patients, which trials suggest they do. Combining several serotonin-raising drugs can cause dangerous serotonin syndrome. Motivation and reward lean more on dopamine.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Are there foods that boost serotonin?
- Eggs, tofu, cheese and bananas contain tryptophan, but diet alone barely moves brain serotonin. Daylight and regular exercise are more consistently recommended.
- Is it safe to take serotonin supplements?
- Supplements like 5-HTP can trigger serotonin syndrome when combined with antidepressants, so check with a doctor first.
Sources reviewed: 2026-10-26
References
- Rapport, M. M., Green, A. A., & Page, I. H. (1948). Serum vasoconstrictor (serotonin). Journal of Biological Chemistry, 176(3), 1243–1251.
- Moncrieff, J., et al. (2022). The serotonin theory of depression: a systematic umbrella review of the evidence. Molecular Psychiatry, 28, 3243–3256.
- Berger, M., Gray, J. A., & Roth, B. L. (2009). The expanded biology of serotonin. Annual Review of Medicine, 60, 355–366.