Serotonin, also known as 5-hydroxytryptamine (5-HT) is an important chemical neurotransmitter found in the human body. Serotonin is manufactured in the brain and the intestines. The majority of the body's serotonin (90%) is found in the gastrointestinal tract where it regulates intestinal movements that stimulate gut motility. The remainder is found in the central nervous system and blood platelets where it plays a role in the formation of blood clots through vasoconstriction. It is synthesized along with its metabolite 5-hydroxtryptophan (5-HTP) from the amino acid L-tryptophan.
Serotonin is popularly thought to contribute to feelings of well-being and happiness. There is no scientific evidence however that low levels of serotonin contribute to depression. Antidepressant medication such as selective reuptake inhibitors (SSRIs) are thought to inhibit the re-absorption or serotonin and norepinephrine neurotransmitters and thus increase levels in the synapse of the nerves of the brain resulting in an elevation of mood. Recreational drugs such as MDMA and cocaine are also thought to inhibit the re-absorption of serotonin to create their highs. Scientists however are still not sure precisely how these drugs work.
It is possible to raise serotonin levels in the body by taking tryptophan and its metabolite 5 HTP. Tryptophan was taken off the market in 1984 when thousands of people developed a severe blood disorder called Eosinophilia - Myalgia Syndrome (EMS). The cause was later traced to a contaminant found in batches of tryptophan manufactured by a Japanese company. The FDA rescinded its restriction of sales of tryptophan in 2001. Both tryptophan and 5-HTP, which is made from the seeds of an African plant Griffonia simplicifolia are readily available in stores that sell nutritional supplements and online. 5-HTP is also a precursor to melatonin, a hormone that regulates sleep-wake cycles. As a supplement it is used to help individuals with insomnia and it is advertised to improve mood and reduce food cravings. Natural ways to increase serotonin are exposure to sunlight and exercise.
In the fall of 2014 I consulted a naturopathic physician who ordered a laboratory test for neurotransmitters from Pharmasan Labs. The test measured levels of serotonin, GABA, glycine, glutamate, histamine, PEA, dopamine, DOPAC, norepinephrine, epinephrine, cortisol and melatonin. My test results showed that all these substances were within normal levels with the exception for serotonin, which was quite low. At that same time I was being treated for Small Intestine Bacterial Overgrowth (SIBO), a condition that causes IBS and fibromyalgia. For more about that read my post on SIBO. The treatment of SIBO includes taking a prokinetic agent that stimulates gut motility to prevent bacteria from staying in the small intestine. One of those prokinetic agents is the drug Resolor that binds to serotonin receptors in the gut. Resolor does not in fact raise serotonin levels and after three months of taking the drug I retested my serotonin levels and they were slightly lower than before. I then decided to take 5HTP. I started with a small dose gradually increasing until I was taking 100 mg. three times a day for 6 weeks. When I retested my serotonin levels they were slightly above normal levels so I decreased my dose slightly. My gastrointestinal symptoms and fibromyalgia have subsided over the past year with SIBO treatments and the addition of 5HTP seems to have helped with this recovery. Taking 5HTP did not improve my sleep which remains disturbed with multiple awakenings throughout the night. I suppose that is not surprising since I do not have low melatonin levels and I have never experienced improvement in my sleep by taking melatonin supplements.
People with fibromyalgia are typically deficient in serotonin. Since serotonin regulates gut motility serotonin deficiency may be a contributing factor to developing gastrointestinal dysfunction, IBS, SIBO and fibromyalgia. Getting tested for neurotransmitters and raising serotonin levels to normal levels by taking 5HTP may be an important part of the treatment of fibromyalgia.