In the United States, about 14.8 million adults have major depressive disorder, according to the National Institute of Mental Health. People with depression have a consistently low mood and might have problems with concentration, activity level, sleeping and eating. Some patients choose to use supplements such as L-tryptophan to treat the disorder. However, scientific evidence has not conclusively proved L-tryptophan's safety nor its effectiveness in relieving depression symptoms.
Function
An essential amino acid, L-tryptophan is converted into the neurotransmitter serotonin when it enters the brain. Narda G. Robinson, DO, DVM, MS, author of the article "Benefiting Brain Chemistry with L-Tryptophan," explains that this process happens in stages. First, the brain converts L-tryptophan to 5-hydroxytryptophan, or 5-HTP, which is then converted into serotonin. Serotonin is linked to mood, and certain antidepressants target this neurotransmitter to improve the symptoms of depression.
Sources
Patients can obtain L-tryptophan either through a supplement or through food. Several types of food contain high levels of tryptophan, including shrimp, mustard greens, crimini mushrooms, chicken breast, tofu, soybeans and spinach. The eMedTV article "Precautions and Warnings With L-Tryptophan" points out that although L-tryptophan supplements were temporarily banned in the United States in the early 1990s, they are again available commercially under the Dietary Supplement Health and Education Act of 1994.
Drug Interactions
L-tryptophan can interfere with certain medications, including antidepressants that patients might already be taking. It also can interfere with another alternative treatment for depression, St. John's wort. One of these interactions involves serotonin syndrome, a dangerous increase in serotonin that can cause symptoms such as hallucinations, diarrhea, fast heartbeat, sweating, fever, muscle spasms and confusion. Patients who are taking antidepressants or St. John's wort should talk to their doctors before starting an L-tryptophan regimen.
Side Effects
Patients who take L-tryptophan supplements may experience side effects such as allergic reactions, stomach pain, nausea, headaches, indigestion and lightheadedness. Getting L-tryptophan through regular food sources should not cause any side effects.
Another possible and serious side effect of L-tryptophan supplementation is eosinophilia-myalgia syndrome, or EMS. With EMS, patients may have nerve pain, skin changes, rashes, fatigue, severe muscle pain and hair loss. The ban on L-tryptophan in the early 1990s was prompted by reports of EMS cases, but there is debate over whether only one contaminated brand of supplements caused these cases or whether all L-tryptophan supplements can cause EMS.
Considerations
People who have kidney disease, liver disease, allergies or eosinophilia might develop problems if they take L-tryptophan supplements. With eosinophilia, patients have a higher amount of eosinophils, a type of white blood cell, in their blood or at a specific location, such as at an infection site. Conditions that may result in eosinophilia include Crohn's disease, lupus, ovarian cancer and asthma. Women who are pregnant or breastfeeding may not be able to take L-tryptophan supplements and should talk to their doctors first.
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