5-HTP & Heart Disease

5-HTP is a chemical substance used by the nerves and platelets. As such, it performs vital functions. One type of tumor, however, can release high amounts of 5-HTP into the bloodstream. If blood levels of 5-HTP are too high, people can develop symptoms as well as damage to a valve within the heart.

What Is 5-HTP?

5-HTP is short for 5-hydroxytryptamine, also referred to as serotonin. It is a neurotransmitter -- a chemical used by the nerves to send signals -- that acts in the nerves of the brain, spinal cord, stomach and intestines. In addition, 5-HTP is stored inside platelets and released from blood clots to make a blood vessel smaller and restrict blood loss, as explained in "Basic & Clinical Pharmacology" by Bertram Katzung, of the Department of Cellular and Molecular Pharmacology at the University of California, and his coauthors.

Carcinoid Syndrome

Carcinoid syndrome is a disorder that develops when a tumor releases 5-HTP. The tumor is usually located in the last section of the small intestine but may also be located in the rectum, appendix, lungs or pancreas, according to Courtney Townsend Jr., M.D., on MerckManuals.com. Because of the high amount of 5-HTP, people may have cramps, diarrhea and facial flushing. They can also develop damage to the valve in the right side of the heart.

5-HTP and Carcinoid Syndrome

In a 2005 issue of "Circulation," Bjorn Gustafsson, M.D., and coauthors reported on research designed to determine if rats given 5-HTP would develop changes like those seen in carcinoid syndrome. Ten rats that received injections of serotonin once a day for three months developed a deficiency of platelets, as well as diarrhea and flushing. In addition, six rats developed heart disease. Four developed damage in one of the valves of the heart, while two developed disease in both valves. Examining the heart valves under a microscope showed areas similar to those seen with carcinoid syndrome.

5-HTP and Heart Disease

Fenfluramine is a medicine that causes the release of 5-HTP. It was a component of the anti-obesity drug called fen phen, which was removed from the market because it caused high blood pressure in the pulmonary artery, the artery that goes from the heart to the lungs, and also caused problems in the heart valves. In the May 2009 issue of "Expert Opinion on Drug Safety," Richard Rothman and coauthor report a study evaluating how this medication causes disease and hypothesize that a substance from the breakdown of fenfluramine is the culprit. Similar to what happens with carcinoid syndrome, the substance caused valvular heart disease.