Serotonin, Serum

Optimal Result: 31 - 207 ng/mL.

Serotonin plays important roles in the resolution of mood, sleep, and appetite.

Serotonin is an inhibitory neurotransmitter synthesized by enzymes that act on tryptophan and/or 5-HTP.

Neurotransmitters are divided into two basic categories:

– Excitatory neurotransmitters stimulate the brain and body.

– Inhibitory neurotransmitters calm the brain and body.

Just as levels of individual neurotransmitters are important in maintaining optimum health, so is the proper balance between your excitatory and inhibitory systems.

Serotonin, generally regarded as the “happiness molecule,” contributes to the feelings of calm and well-being that eases depression and anxiety, supports sleep, and decreases appetite.

Serotonin is stored in presynaptic vesicles and released to transmit electrochemical signals across the synapse. Extensive research has been conducted surrounding serotonin and acts as a target for symptoms like low mood, compulsions, anxiousness, and headaches.

Serotonin acts, in most cases, as an inhibitory neurotransmitter and, like GABA, modulates neuron voltage potentials to inhibit glutamate activity and neurotransmitter firing. Serotonin neurons have large numbers of axons and are important in integrating neural circuits. This also provides an explanation for serotonin’s role in so many health concerns.


– How to increase serotonin in the human brain without drugs [L]

– Carcinoid Syndrome [L]

Kamoun P, Douay O. Sérotonine et autisme [Serotonin and autism]. Ann Biol Clin (Paris). 1980;38(4):201-5. French. PMID: 6160783.

Leibowitz SF. The role of serotonin in eating disorders. Drugs. 1990;39 Suppl 3:33-48. doi: 10.2165/00003495-199000393-00005. PMID: 2197074.

Stasi C, Sadalla S, Milani S. The Relationship Between the Serotonin Metabolism, Gut-Microbiota and the Gut-Brain Axis. Curr Drug Metab. 2019;20(8):646-655. doi: 10.2174/1389200220666190725115503. PMID: 31345143.

Moroianu LA, Cecilia C, Ardeleanu V, Pantea Stoian A, Cristescu V, Barbu RE, Moroianu M. Clinical Study of Serum Serotonin as a Screening Marker for Anxiety and Depression in Patients with Type 2 Diabetes. Medicina (Kaunas). 2022 May 11;58(5):652. doi: 10.3390/medicina58050652. PMID: 35630069; PMCID: PMC9146121.

What does it mean if your Serotonin, Serum result is too low?

A low serotonin level in serum can signify several potential implications for an individual's health and well-being:

→ Mood Disorders: Low serotonin levels have been associated with mood disorders such as depression and anxiety. Serotonin is often referred to as the "feel-good" neurotransmitter, and insufficient levels can contribute to feelings of sadness and low mood.

→ Sleep Disturbances: Serotonin plays a crucial role in regulating sleep patterns. Low serotonin levels may lead to sleep disturbances, including insomnia and difficulty maintaining a regular sleep-wake cycle.

→ Digestive Issues: Serotonin is also involved in regulating gastrointestinal functions. Low serotonin levels can contribute to digestive problems such as irritable bowel syndrome (IBS) and changes in appetite.

→ Nausea: Serotonin is known to influence nausea and vomiting. Low levels of serotonin may contribute to increased susceptibility to nausea and a reduced ability to tolerate motion sickness.

→ Bone Health: Emerging research suggests a potential link between low serotonin levels and bone health. Insufficient serotonin may impact bone density and remodeling.

→ Blood Clotting: Serotonin plays a role in blood clotting, and low levels may affect this process. It can influence the risk of excessive bleeding or clot formation.

Serotonin levels may be increased by exercise, increased daylight (or daylight equivalent) exposure, low-protein or high-carbohydrate meals, insulin, or by Tryptophan or 5-hydroxytryptophan (5-HTP) supplements.

Some studies indicate that therapeutic massage may also elevate serotonin levels.

The herbs St. John’s wort and ginseng may elevate serotonin levels.

It's important to note that while low serotonin levels can be associated with these conditions, serotonin's role in health is complex and not fully understood. Additionally, other factors, including genetics and lifestyle, can contribute to these conditions. If you suspect low serotonin levels may be affecting your health, it's crucial to consult with a healthcare professional who can provide a comprehensive evaluation and appropriate treatment options.

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