After many years of being banned in the United States, L-tryptophan is once again available over-the-counter. L-tryptophan is an essential amino acid that is found in a number of foods, and is found in particularly high quantities in Atlantic cod, soybeans, cheddar cheese, and pumpkin seeds. It can be purchased at health food stores and alternative medical clinics across the country, where it is sold as a nutritional supplement. L-tryptophan is a precursor needed for the synthesis of both melatonin and serotonin, suggesting to some that it may be helpful for disorders characterized by a deficiency of these neurotransmitters.
Depression
Most models of clinical depression suggest that a deficiency in synaptic serotonin is a causative factor in the development of the disease. Anti-depression medications are classified as first generation, including monamine oxidase inhibitors; second generation, including tricyclics and tetra cyclics; and third generation, the selective serotonin reuptake inhibitors. All are believed to work by increasing the levels of synaptic serotonin, although all by different mechanisms. According to the Mayo Clinic, l-tryptophan increases the body's production of serotonin by increasing the amount of available precursor material for its synthesis. Since l-tryptophan can be synthesized into other neurotransmitters, and since it requires a number of other nutrients to be converted into serotonin, it is highly unlikely that l-tryptophan supplementation alone can cause serotonin syndrome.
Drug Interactions
The Mayo Clinic takes an unusual stance in its recommendation of l-tryptophan, also known as the pharmaceutical drug Aminomine. Although it is known that l-tryptophan interacts with several pharmaceutical anti-depressant drugs, the Mayo Clinic does not discourage their concomitant use. The combination of l-tryptophan with some anti-depressants appears to improve their efficacy, although doses must be closely monitored by a doctor to ensure that serotonin syndrome is not developed. In fact, the clinic recommends that fluvoxamine be administered alongside l-tryptophan. However, the University of Maryland Medical Center advises that under no circumstance should l-tryptophan be combined with isocarboxazid, phenelzine, tramadol, tranylcypromine, or triptine migraine medications, as they can dramatically increase the risk of serotonin syndrome.
Serotonin Syndrome
Since serotonin is found throughout the body and is involved in the regulation of sleep, pain, happiness, stress, aggression, and digestion, an overdose has a complex pathophysiology. The syndrome is caused when the central nervous system releases or is unable to eliminate an excess amount of serotonin in the synapses of nerves in the brain and spinal cord. While early studies indicated that overstimulation of the 5-HT1A receptor sites in the medulla and central gray nuclei, later studies suggest that the symptoms are caused primarily by 5-HT2A receptors site agonism. The 5-HT1A receptor may still be involved indirectly. Increased serum levels of serotonin in these locations are believed to cause a similar increase in central nervous system norepinephrine levels, which may be responsible for the majority of the symptoms of serotonin syndrome. Gamma Amino Butyric Acid and NMDA receptor antagonists may also be peripherally involved. When serotonin syndrome is caused by the use of monamine oxidase inhibiting drugs, it is particularly worrisome, as their effects on the body's natural means of clearing serotonin can take as long as four weeks to wear off.
Symptoms
If you are taking l-tryptophan and begin to suffer from involuntary muscle twitching, agitation, confusion, overactive reflexes, and fever, seek emergency medical treatment immediately. Nausea, vomiting, and diarrhea may accompany these symptoms, as may sweating, abdominal cramps, skin flushing, high blood pressure, chills, and hallucinations. According to the National Institute of Health, serotonin syndrome can cause coma or death if not treated immediately. Patient outcomes are good, however, for those who seek treatment immediately, with recovery common within 24 hours.
