Phenylethylamine as a possible cause of "runner's high"
- A constituent of chocolate that has been suggested as a possible cause of
'chocoholism' (addiction to chocolate) is also being touted as a possible
cause of the feelings of euphoria ("runner's high") experienced by many
It would be interesting if the same chemical--phenylethylamine--did turn out
to be responsible for encouraging both running (which is associated with low
body weight and high physical fitness) and bingeing on chocolate (which is
more likely to be associated with obesity and sedentary lifestyle than with
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>From BBC Science/Tech - online (27 Sep 01):Scientists may have identified a chemical which could explain why exercise
is an anti-depressant. Until now, it has not been clear why exercise has
that effect. But, doctors from Nottingham Trent University suggest the
chemical phenylethylamine could play a part.
Phenylethylamine is a naturally produced chemical that has been linked to
the regulation of physical energy, mood and attention. An enzyme changes the
chemical into phenylacetic acid. There is evidence that levels of both
substances are low in the biological fluids of depressed patients. In what
are thought to be the first attempts to test the effects of exercise on
levels of the chemical, the researchers found, overall, levels of the acid
increased by 77% after exercise.
Twenty healthy men, with an average age of 22 were tested. All regularly did
around four hours of moderate to hard aerobic and
anaerobic exercise each week. Before the study began, they refrained from
exercise for a day, and a urine test was done to check for levels of
phenylacetic acid, the most accurate measurement of the chemical. The next,
the men exercised on a treadmill at 70% of their maximum heart rate capacity
for 30 minutes. Doctors chose that level because mood changes are commonly
reported at that level. The men were also asked to rate how hard they had
found the exercise. When urine levels were checked, it was found
phenylacetic acid levels were increased in 18 out of the 20 participants.
Though the average increase in levels was 77%, the increases in individuals
ranged from 14 to 572%. But the highest rises were seen in two out of the
three who had rated the exercise as hard.
The research team say though there may be many factors involved in the
phenylacetic acid response, because its chemical structure is very similar
to that of amphetamines, it may be that this chemical is part of a "runner's
high", a phenomenon linked to natural endorphin activity in the brain. They
suggest phenylacetic acid could also be important because it can cross from
the blood to the brain, something endorphins cannot do.
Dr Ellen Billet, who was one of the team of researchers from Nottingham
Trent who carried out the research, told BBC News Online: "We felt there may
be an effect of exercise on phenylethylamine." GPs can prescribe a drug
based on the chemical which is known to have beneficial effects on patients.
Dr Billet said: "We also know that moderate exercise has these beneficial
effects. "So we wondered 'what if this was how exercise works'". She said
more research needed to be done to develop their initial finding, including
why different people's phenylethylamine levels are affected in different
ways by exercise and if different kinds of exercise have the same effects.
But she said people should still exercise, because of its benefits on both
mental and physical health.
"This could be used as and adjunct." A spokeswoman for the mental health
charity Mind said: "Physical exercise has a valid place in the treatment and
prevention of some mental health problems. "In a recent Mind survey of
Cannons gym users, 75 % said they exercised to reduce their stress levels
and 67% said they used exercise to maintain their mental health, like
lifting 'low' moods. "Mind is calling for all GPs to offer exercise sessions
on prescription to patients with mental health problems, particularly as we
know that most people with mental health problems don't know this non-drug
'treatment' option exists."
The research was published in the British Journal of Sports Medicine.
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