5-Hydroxytryptophan (5-HTP) for Weight Loss

Is there enough evidence to support using this supplement for weight loss?

A natural substance that may reduce hunger cravings, 5-HTP (5-Hydroxytryptophan) is a byproduct of L-tryptophan, a type of protein found in a number of foods. When used as a weight loss aid, 5-HTP is typically sourced from the seeds of the Griffonia simplicifolia plant.

5-HTP is known to increase the production of serotonin in the brain and central nervous system. A type of neurotransmitter (a chemical responsible for carrying messages between nerve cells), serotonin helps regulate appetite. Therefore, some alternative medicine proponents claim that consumption of 5-HTP can help promote weight loss by keeping your appetite in check and, in turn, reducing your food intake.

What the Research Says About the Benefits of 5-Hydroxytryptophan

According to the National Institutes of Health (NIH), there is not yet enough scientific evidence to rate the effectiveness of taking 5-HTP supplements for weight loss or obesity. However, the NIH notes that some preliminary research indicates that 5-HTP may help curb appetite, decrease caloric intake, and reduce weight in obese people.

The available research includes an older study from 1992 published in the American Journal of Clinical Nutrition. For the study, 20 obese participants were randomly assigned to receive either 5-HTP or a placebo for two six-week periods. While no diet was prescribed in the first study period, a reduced-calorie diet was recommended for the second. Study results showed that members of the 5-HTP group experienced significant weight loss during both periods. In addition, members of the 5-HTP group had a reduction in carbohydrate intake and a tendency to experience satiety (a feeling of fullness) earlier on when eating.

In another study (published in the International Journal of Obesity and Related Metabolic Disorders in 1998), researchers found that 5-HTP significantly decreased daily intake of calories and reduced body weight in overweight adults with type 2 diabetes. The study involved 20 overweight adults with type 2 diabetes, nine of whom were given 5-HTP and 11 given a placebo.

There is a lack of more recent research on the effectiveness of 5-HTP in promoting weight loss.

Possible Serious Side Effects of 5-HTP

According to the NIH, use of 5-HTP supplements may be linked to eosinophilia-myalgia syndrome (EMS), a serious condition that causes extreme muscle tenderness and blood abnormalities.

In 1989 and 1990, there was an epidemic of EMS among people who had ingested L-tryptophan (a precursor to 5-HTP). Upon investigation, the epidemic was traced back to a single source and attributed to contamination resulting from inadequate purification coupled with a then newly introduced fermentation process. Although commercial production of 5-HTP does not use such fermentation processes, the NIH advises avoiding use of 5-HTP supplements until more is known about their safety.

It's important to keep in mind that supplements haven't been tested for safety and dietary supplements are largely unregulated. In some cases, the product may deliver doses that differ from the specified amount for each herb. In other cases, the product may be contaminated with other substances such as metals. Also, the safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications has not been established. 

5-HTP is also known to trigger a number of side effects, including:

  • Heartburn
  • Stomach pain
  • Nausea
  • Vomiting
  • Diarrhea
  • Drowsiness
  • Sexual problems
  • Muscle problems

Known 5-HTP Drug Interactions 

In addition, taking 5-HTP in combination with certain medications may produce harmful effects. These medications include antidepressant drugs (such as Prozac® and Zoloft®), dextromethorphan (Robitussin DM®, and others), and meperidine (Demerol®). 5-HTP may also interact with a number of herbal supplements, including St. John's wort and S-adenosylmethionine.

Using 5-HTP for Weight Loss

Due to safety concerns, the NIH advises against taking 5-HTP in supplement form. In addition, there's little evidence to support the claim that 5-HTP supplements can support weight loss.

If you're considering the use of 5-HTP supplements for weight loss (or for any other health-related purpose), it's important to consult your care provider before starting your supplement regimen. Self-treating and avoiding or delaying standard care can have serious consequences.

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  1. MedlinePlus. 5-HTP. Updated June 4, 2020.

  2. Cangiano C, Ceci F, Cascino A, et al. Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophanAm J Clin Nutr. 1992;56(5):863‐867. doi:10.1093/ajcn/56.5.863

  3. Cangiano C, Laviano A, Del Ben M, et al. Effects of oral 5-hydroxy-tryptophan on energy intake and macronutrient selection in non-insulin dependent diabetic patientsInt J Obes Relat Metab Disord. 1998;22(7):648‐654. doi:10.1038/sj.ijo.0800642