Even moderate exercise apparently raises levels of a brain chemical that improves a person’s mood. The substance is phenylethylamine, or PEA, a natural stimulant produced by the body. It is related to amphetamines but does not have the long-lasting effects that make “speed” or “ice” such deadly drugs.

Now a British research team reports early findings suggesting that moderate exercise increase PEA levels for most people. They argue that this increase causes the euphoric mood often called “runners’ high.” And because depressed people tend to have low PEA levels, the researchers say there now is an explanation of why exercise has a natural antidepressant action.

“We are not advocating PEA as a drug,” says study author E. Ellen Billett, Ph.D. “What we are trying to say is now there is more chemical evidence for why runners’ high occurs. We hope this information might give doctors more confidence in prescribing exercise for mild depression and as an adjunct to drug therapy.”

Hector Sabelli, MD, Ph.D., studied PEA while a professor at Chicago’s Rush University. Now director of the Chicago Center for Creative Development, Sabelli says that the new findings fit exactly with all of his own experiments.

So what about the natural substances called endorphins, which have previously been linked to runners’ high? Billett says that endorphins don’t penetrate the brain as easily as PEA does- so she thinks PEA may be the true basis for the good mood one gets from a workout. Sabelli is not so quick to rule out endorphins, however, and says that the natural compounds probably interact in various ways.

“We think PEA is part of the reward of exercise,” Billett says, adding that it might be affecting other brain chemicals and that it’s likely there are normal differences between individuals. “Some will respond to exercise, some won’t.”

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