The Centers for Disease Control and Prevention (CDC) recently reported that 73 percent of all U.S. children consume caffeine on a daily basis. Now a new study from the University of Buffalo School of Public Health and Health Professions has found that caffeine has a greater effect on post-puberty boys than girls. The study was initially investigating whether puberty affected the cardiovascular changes brought on by caffeine. Previous research had already shown that its use increased blood pressure and reduced heart rates in children, teens and adults.
A 2008 study from the University of Barcelona established that caffeine has a greater effect on men than women. The new study, published in the journal Pediatrics, included 96 children. Researchers monitored blood pressure and heart rate in the children before and after either caffeine or placebo intake. The study included both post-pubertal and pre-pubertal children. One of the researchers, Jennifer Temple, PhD, said that they not only found an interaction between caffeine dose and gender, but only in the post-puberty children.
The study also looked at whether cardiovascular responses to caffeine differed through the phases of the menstrual cycle in post-puberty girls, and found that responses included greater decreases in heart rate during the mid-luteal phase, and blood pressure increases that were greater in the mid-follicular phase. The follicular phase starts on the first day of the menstrual cycle and ends with ovulation. The luteal phase is characterized by an increase in progesterone and follows ovulation.
Researchers are not certain why there are gender differences in the effects of caffeine on the post-puberty boys and girls, but find it concerning that the effects came at low doses. The FDA announced last year that they were beginning to look into the safety of caffeine for youth and adolescents. Although the FDA says that caffeine intake of up to 400 mg per day is not typically associated with negative side effects for adults, they have not yet set recommendations for children and adolescents. The American Academy of Pediatrics recommends that caffeine not be included in a child’s diet.
The CDC said recently that although children and adolescents have not increased their overall caffeine consumption, it is coming from a larger variety of sources, including coffee and energy drinks. They have particularly been looking at products with added caffeine, such as energy drinks, which the FDA reports have been associated with at least 13 teen deaths.
The FDA does not require that food labels include information on the amount of caffeine since it is a natural chemical found in items like coffee beans. It is regulated as an ingredient rather than a drug. Since energy drinks are sold as dietary supplements they are not regulated, and a 2012 Consumer Reports review said that 11 of the 27 best-selling energy drinks did not list their caffeine content.
The newest study had some weaknesses because the group was primarily white, well-educated and middle class, and the researchers could not be completely certain that the control groups, which received placebos, did not consume any caffeine. However, it did clarify differences in the physiological response to caffeine by puberty and gender, and identified the same increased effect on boys than girls as previous studies found in adults.
By Beth A. Balen