Confidence Cuisine

Increasing the intake of tryptophan, the essential amino acid found in high-protein foods, may make people behave more assertively.

By Allison Peters, published on September 1, 2001 - last reviewed on June 9, 2016

What if there were a magic pill that could make you feel more in control of your life? In a sense, one already exists.

Debbie Moskowitz, Ph.D., a psychology professor at McGill University in Montreal, recently discovered that upping the intake of tryptophan--the essential amino acid found in high-protein foods such as turkey and milk--may make people behave more assertively.

In her study, nondepressed people who took three grams of tryptophan for 12 days seemed more goal-oriented--making suggestions and placing demands on others--than did those who took a placebo. The subjects also acted less disagreeable and sarcastic.

Moskowitz's findings, scheduled for publication in the journal Neuropsychopharmocology, lead her to believe that tryptophan works by maximizing the body's synthesis of serotonin, the neurotransmitter that acts as a natural antidepressant.

"Our bodies make enough serotonin so that most of the time we don't act submissive and quarrelsome," says Moskowitz. "But this study suggests that maximizing our serotonin with tryptophan will help us behave even more dominantly and less argumentatively, which can keep us feeling confident and help us accomplish our goals."

Unfortunately, just upping your intake of high protein foods won't do the trick, because so many other amino acids in protein compete with tryptophan for transport to the brain. Instead, you need to take purified supplements that contain no other amino acids. But talk to your physician first, advises Moskowitz, because there have been contamination problems with tryptophan supplements in the past.