Serotonin or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract (GI tract), blood platelets, and the central nervous system (CNS) of animals, including humans. It is popularly thought to be a contributor to feelings of well-being and happiness.

Functions of serotonin
As a neurotransmitter, serotonin influences both directly and indirectly the majority of brain cells. The following is a list of things that it is thought that serotonin could affect:


1. Bowel function. Most of the body's serotonin is found in the gastrointestinal tract where it regulates bowel function and movements. It also plays a part in reducing the appetite while consuming a meal.
2. Mood. It is most well known for its role in the brain where it plays a major part in mood, anxiety and happiness. Illicit mood-altering drugs such as Ecstasy and LSD cause a massive rise in serotonin levels.
3. Clotting. Its third major role is in the formation of blood clots. Serotonin is released by platelets when there is a wound, and the resulting vasoconstriction (narrowing of the tiny arteries - arterioles) reduces blood flow and aids the formation of blood clots.
4. Nausea. If you eat something that is toxic or irritating, more serotonin is produced in the gut to increase transit time and expel the irritant in diarrhea. This increase in blood serotonin levels also causes nausea by stimulating the nausea area in the brain.
5. Bone density. Studies have shown that a persistent high level of serotonin in the bones can lead to an increase in osteoporosis.
6. Sexual function. Low serotonin levels in the intoxicated state are thought to contribute to the associated increase in libido, while those taking medication that increase serotonin levels are seen to have a reduction in libido and sexual function.