Caffeine Affects Adolescent Boys, Girls Differently, Study Finds

Caffeine intake by children and adolescents has been rising for decades. The popularity of caffeinated sodas and energy drinks, which now are marketed to children as young as four, is largely to blame.

Little research exists on the effects of caffeine on young people despite this popularity.

Jennifer Temple, PhD, associate professor in the Department of Exercise and Nutrition Sciences, University at Buffalo is among the few researchers who are conducting such investigations.

Her latest study finds that after puberty, boys and girls experience different heart rate and blood pressure changes after consuming caffeine. Girls also experience some differences in caffeine effect during their menstrual cycles.

Gender Differences in Responses to Caffeine

Past studies, including those by this research team, have shown that caffeine increases blood pressure and decreases heart rate in children, teens and adults, including pre-adolescent boys and girls. The purpose here was to learn whether gender differences in cardiovascular responses to caffeine emerge after puberty and if those responses differ across phases of the menstrual cycle.

Temple says:

“We found an interaction between gender and caffeine dose, with boys having a greater response to caffeine than girls, as well as interactions between pubertal phase, gender and caffeine dose, with gender differences present in post-pubertal, but not in pre-pubertal, participants.

We found differences in responses to caffeine across the menstrual cycle in post-pubertal girls, with decreases in heart rate that were greater in the mid-luteal phase and blood pressure increases that were greater in the mid-follicular phase of the menstrual cycle.

In this study, we were looking exclusively into the physical results of caffeine ingestion.”

Physiological Factors

Phases of the menstrual cycle, marked by changing levels of hormones, are the follicular phase, which begins on the first day of menstruation and ends with ovulation, and the luteal phase, which follows ovulation and is marked by significantly higher levels of progesterone than the previous phase.

Future research in this area will determine the extent to which gender differences are mediated by physiological factors such as steroid hormone level or by differences in patterns of caffeine use, caffeine use by peers or more autonomy and control over beverage purchases, Temple says.

The double-blind, placebo-controlled, dose-response study examined heart rate and blood pressure before and after administration of placebo and two doses of caffeine (1 and 2 mg/kg) in pre-pubertal (8- to 9-year-old; n = 52) and post-pubertal (15- to 17-year-old; n = 49) boys (n = 54) and girls (n = 47).

Reference:

Jennifer L. Temple, Amanda M. Ziegler, Adam Graczyk, Ashley Bendlin, Teresa Sion, and Karina Vattana. Cardiovascular Responses to Caffeine by Gender and Pubertal Stage.
Pediatrics, June 2014 DOI: 10.1542/peds.2013-3962

Photo: Surian Soosay/flickr