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Diet and Nutrition

5-htp Serotonin Medication Concerns



I have been reading about 5-HTP as a substance for reducing hunger during a diet. Is this substance in anyway harmful to take, and what are recommended dosages?


5-htp Serotonin has been touted as an anti-depressant similar to Prozac that works as a direct precursor to serotonin. Serotonin is a neurotransmitter (chemical messenger) made by brain cells that makes you sleepy, lessens pain and decreases appetite. Serotonin is made when you eat carbohydrates, which stimulates the production of the hormone insulin. Insulin secretion causes amino acids circulating in the blood to be taken up by muscle tissue. One particular amino acid (Tryptophan) is taken to the brain where it triggers the production of serotonin. Tryptophan has been restricted as an over the counter supplement by the FDA. 5-HTP(hydroxytryptophan) is being sold as a "safe and natural alternative to the anti-depressant Prozac". 5-HTP is synthesized in the body from the amino acid Tryptophan, and is the immediate precursor of serotonin (which is found in the brain, blood platelets, and mucosal cells of the duodenum (small intestine). Since serotonin is found in the brain and central nervous system, it has several implications in mood, behavior and sleep patterns. Prozac is a selective serotonin reuptake inhibitor which works by increasing the availability of serotonin in certain brain synapses. There have been a few human studies using 5-HTP in comparison with traditional anti-depressants. A 6 week clinical trial by R.S Khan with obese patients found that those supplemented with 5-HTP were able to reduce carbohydrate intake and experienced a feeling of early satiety which resulted in significant weight loss. However, this substance was only tested for 6 weeks in obese patients, so long term use and side effects are unknown. A typical dosage of 5-HTP is a 50 mg capsule with each meal "along with a healthy dietary and lifestyle plan". Doses may vary in individuals depending on how many meals a person eats per day. As for safety, 5-HTP should not be used in conjunction with other anti-depressants (including the herb St. John's Wort)or MAO (monamine oxidase) inhibitors. This product has not been approved by the FDA, so side effects and safety are truly unknown at this time. Before taking any natural remedy for weight loss or other ailments, I would consult your physician. In the meantime, the safest and healthiest way to lose weight is to decrease the fat and calories in your diet, and increase physical activity. A registered dietitian can assist you with weight reduction if needed. Good luck to you. Sincerely, Lisa M. Cicciarello, MEd, RD, CNSD VA Medical Center, Cincinnati, Ohio References: Serotonin and Neuropsychiatric Disorders, Pharmacological Reviews Vol. 43, No. 4, 1991 Eating Behavior in obese adult treated with 5-HTP, American Journal of Clinical Nutrition, 1992;56:863-867

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Response by:

Kathleen Rourke, PhD, RN, RD, CHES
Formerly, Associate Dean
College of Allied Health Sciences
University of Cincinnati