Girls and Boys React Differently to Caffeine Starting at Puberty

In this Feb. 11, 2014 file photo, thousands of empty and crushed soda cans build up on a conveyer belt near the end of the line at Tennis Sanitation in Saint Paul Park, Minn.
In this Feb. 11, 2014 file photo, thousands of empty and crushed soda cans build up on a conveyer belt near the end of the line at Tennis Sanitation in Saint Paul Park, Minn. –AP Photo/The St. Paul Pioneer Press, John Doman

Caffeine isn’t healthy, but that’s no news. The withdrawal headaches, jitteriness and dehydration kind of gave that one way. What is news, however, is that starting at puberty, it’s worse for boys than girls.

Girls and boys have the same cardiovascular reactions to caffeine in childhood, but begin to react differently in adolescence, finds a new study conducted by researchers from The University of Buffalo.

In the double-blind study published in the June issue of Pediatrics, researchers examined the cardiovascular reactions of 52 pre-pubescent (ages eight to nine) and 49 post-pubescent (ages 15 to 17) children to varying levels of caffeine. Participants consumed either the placebo, 1 mg/kg or 2 mg/kg caffeinated sodas, and then had their heart rates and blood pressures taken. The results found that pre-pubescent children had the same reaction to caffeine regardless of gender, while post-pubescent boys had much stronger cardiovascular reactions to caffeine than girls.

Mean6SEMchanges in average heart rate (HR). between 0- and 2-mg/kg doses of caffeine in prepubertal and postpubertal boys and girls. Because there were no effects of time and no differences between the 1- and 2-mg/kg doses, the data shown are the average changes frombaseline and are fromthe 2-mg/kg condition. *Significantly different from postpubertal boys, P , .05. —PEDIATRICS Volume 134, Number 1, July 2014

The study also examined post-pubescent girls’ reactions to caffeine at various phases of their menstrual cycles. At different stages of the cycle, the girls metabolized caffeine differently.

“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,’’ Dr. Jennifer Temple, one of the researchers who conducted the study said in a University at Buffalo press release announcing the study.

(“Pubertal’’ is another way to refer to puberty.) While the data concludes that there are gender differences in cardiovascular responses to caffeine that begin to occur at puberty, the researchers aren’t sure reactions are a result of biology or physiology. The researchers proposed that these differences could either stem from horomone levels after puberty or from societal differences in caffeine consumption (for instance, the study says girls consume less caffeine than boys).

For the pro-basketball aspiring boys, “caffeine will stunt your growth’’ might be a scary enough warning to keep them away from the Monster. But if height isn’t a serious enough threat, you can add blood pressure, heart rate and cardiovascular issues to the long list of reasons they can’t have soda.

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