Recent research done by University of Buffalo scientists on caffeine’s effects on teenagers revealed unexpected results. Teenage boys showed little tolerance to caffeine, while teenage girls were less affected by caffeine’s chemical stimulants.
In the experiment, a teenager would sit down in a room with a reclining chair, fill out a questionnaire, pick a movie to watch and consume a 12-ounce drink that contained 0, 50, 100 or 200 milligrams of caffeine. There were three separate trials, each testing a different caffeine dose. The study was a “double-blind” study, meaning neither the teenagers nor the researchers knew how much caffeine was given at the time.
The subjects were tested every 10 minutes – for an hour – for their blood pressure and heart rate responses to the caffeine intake.
“The goal of the study was to determine if cardiovascular response varied as a function of drug and chronic caffeine use in adolescents,” said Jennifer Temple, assistant professor of the department of exercise and nutrition sciences at the University of Buffalo.
Temple said that she and her fellow researchers hypothesized that high consumers of caffeine would show lower responses to caffeine intake than consumers who had little caffeine, due to tolerance.
She said that their findings were not consistent with their hypothesis, and that males actually showed a complete opposite response in their blood pressure responses than the research team anticipated.
“We found that there were dose-dependent decreases in heart rate and increases in blood pressure. Males showed differences in blood pressure responses as a function of chronic caffeine use, but females did not,” Temple said. “We think that males feel stronger effects of caffeine than females; however, we do not know if this is a physiological difference, or whether it relates to different patterns and amounts of consumption.”
She said the differences in male and female reactions to caffeine could be related to differences in the rates of caffeine consumption between sexes. If a male and a female both consume 100 mg of caffeine per day, the male might consume the 100 mg at once, while the female might consume four cups of tea – with 25 mg of caffeine each – throughout the day.
She said that males reported using caffeine to get a rush and to improve sports performance significantly more than females.
“We have not seen much evidence of tolerance. It could be because at this age, consumption of caffeine is still sporadic, and in our population, the levels were pretty low – 50 to 60 mg per day on average. It is possible that higher chronic doses of caffeine are necessary to achieve tolerance,” Temple said.
UC Davis students have mixed attitudes toward caffeine consumption.
Eileen Ruan, a senior history major at UC Davis, said she consumes three to four shots of espressos and one cup of tea per day.
“I’m addicted to [caffeine]. If I don’t drink it, I get a headache,” she said.
Ruan said that she mainly consumes caffeine for an energy boost, a sentiment shared by Marc Perkel, a senior psychology major.
“It depends on the day. If I have an early class, I need it,” Perkel said.
“Caffeine’s effects are highly variable across individuals,” Temple said. “In general, moderate doses of caffeine decrease fatigue, increase wakefulness, improve attention, increase blood pressure and decrease heart rate. High doses of caffeine lead to feelings of jitteriness, anxiety and nausea.”
The results of Temple’s study were unexpected, and students will have to choose for themselves whether to get in line for another espresso during this finals season.
ERIC C. LIPSKY can be reached at science@theaggie.org.
