5-HTP decreases food intake in stressed rats and those deprived of food

5-Hydroxy-L-tyrptophan (5-HTP) dose-dependently decreased food intake in rats deprived of food, and in rats that were stressed according to a study by Richard Wurtman of the Massachusetts Institute of Technology and Tim Maher from the Massachusetts College of Pharmacy and Health Sciences in Boston, Mass.

The reduction of food intake was dose-dependent, that is, the higher the dose the greater the effect.

5-HTP eight times more effective at reducing stress-induced eating

However, the effect was at least 8 times more effective for the rats that were stressed than those that had been deprived of food.

The amino acid L-valine blocked the effect

The effect was blocked by giving rats the amino acid L-valine—another large neutral amino acid which competes with 5-HTP for taxi molecules to carry them into the brain.

This suggests that 5-HTP should be taken away from protein. (Amino acids such as L-valine are the building blocks of protein.)

No carbidopa necessary

This appetite suppression occurred without giving the animals a drug called carbidopa which prevents 5-HTP from being converted to serotonin in the body before reaching the brain.

Some researchers previously believed that it was necessary to give 5-HTP with carbidopa to be effect, however, this does not seem to be the case.

Conclusion: 5-HTP may reduce stress-induced eating

“These observations suggest that 5-HTP may be useful in controlling the excessive food intake sometimes generated by stress, even if given without decarboxylase inhibitors [carbidopa] or other drugs,” the researchers concluded.

5-HTP is the immediate precursor to serotonin

5-HTP is the immediate precursor to serotonin.

5-HTP increases leptin, carbidopa reduces this effect

A previous study found that 5-HTP increases leptin—the hormone released by fat cells that decreases appetite and may increase metabolism.

However, they also found that giving carbidopa with 5-HTP suppressed this effect, suggesting that it is better to give 5-HTP alone than with carbidopa.

Practical advice: 5-HTP should be taken on an empty stomach

5-HTP should be taken on an empty stomach away from protein. This study shows that taking it with protein will block the effect.

Other articles about 5-HTP

Other articles about 5-HTP can be found here.

REFERENCE

Amer A, Breu J, Mcdermott J, Wurtman R, Maher T. 5-hydroxy-l-tryptophan suppresses food intake in food-deprived and stressed rats. Pharmacol Biochem Behav. 2004 Jan, 77(1):137-43.

AUTHOR’S CONTACT INFORMATION

A. Amer
Department of Pharmaceutical Sciences
Massachusetts College of Pharmacy and Health Sciences
Boston, MA, US

Articles on the same subject can be found here:

• 5-HTP (5-Hydroxytryptophan)

• Stress