DEAR DR. BLONZ: Please explain tryptophan's role in foods, and the reason it is being promoted as a separate dietary supplement called 5-HTP. -- C.L., Phoenix
DEAR C.L.: 5-HTP stands for 5-hydroxytryptophan. The key part of this compound is tryptophan, an essential amino acid and one of the building blocks of any complete protein.
During digestion, proteins routinely get broken down into their amino acid constituent parts. This is a necessary step before absorption, because intact proteins are too large to pass through the absorptive surface. After absorption, amino acids become available to participate in a number of biochemical functions, including being used to make new proteins or serve as building blocks for other substances needed by the body at the moment.
The first stop after absorption is the liver: our body's great processing plant. The liver plays a key role in the metabolism of proteins, fats and carbohydrates, as well as detoxification and biosynthesis. Think of the liver as having a grand conceptual "to do" list: changing and directing substances toward their new assignments, or packaging and labeling them for elimination from the body.
When tryptophan enters the liver, one option is for it to be made into a key neurotransmitter (brain chemical) called serotonin, which, among other things, encourages relaxation. When the body is unable to sustain needed levels of serotonin, a number of problems can develop, including depression and insomnia. Indeed, many antidepressant medications are specifically designed to maintain levels of serotonin in the brain.
5-HTP is an intermediary substance along the pathway by which serotonin is made from tryptophan. 5-HTP is normally converted to serotonin in the brain and, once made, it is unable to cross the blood-brain barrier and circulate in the rest of the body. However, when 5-HTP is taken as a dietary supplement, serotonin can be produced outside the brain, which might contribute to unwanted side effects. Safety concerns for 5-HTP include drowsiness, gastrointestinal distress and muscle problems.
Another issue is the risk of spasms of the coronary blood vessels that might increase the risk of a heart attack. Anyone at risk for coronary heart disease, and those taking antidepressants, anti-anxiety drugs (SSRIs) or MAO-inhibitor medications, should be sure to check with their physician before considering this substance. (See https://goo.gl/s2Jdda for a summary of typical uses and concerns regarding 5-HTP.)
There is research evidence attesting to the potential benefits from 5-HTP in specific circumstances, but there are also concerns, as listed above. You make no mention of why you are interested in this substance, and that makes it difficult to say whether current research supports your intended use.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to firstname.lastname@example.org. Due to the volume of mail, personal replies cannot be provided.