News article

Physiological Responses To Caffeine May Increase With Age: Study

Posted:  Friday, June 27, 2014

The potentially negative effects of caffeine consumption on the heart significantly increase as young people reach adolescence, research has suggested. Previously studies on adults suggested consumption of as little as 1-3 mg/kg of caffeine - at low to moderate levels - was enough to increase blood pressure and lower heart rate, however evidence of its effects on children was inconsistent, said the report on cardiovascular responses.

“Caffeine use among children is increasing and little research has been done to understand the effects of caffeine in this population,” associate professor at the University of Buffalo, Jennifer Temple, said.

“It is critical that we understand how caffeine affects children so that we can develop evidence-based recommendations for caffeine consumption.”

This latest US study analysed the effects of caffeine on children as young as eight years old, and found that doses of one to two mg/kg reduced subjects’ heart rates and increased blood pressure, compared with the placebo.

“We found changes in cardiovascular response with doses as low as 33 mg, which is less than a can of soda. The heart rate changes were between three and eight beats per minute and the blood pressure changes were between one and two mmHg [millimetres of mercury- a unit pressure measurement],” explained Temple.

Despite widespread use among children and adolescents, there has been little research on the effects of caffeine on young people. Now, a new study from researchers at the University at Buffalo School of Public Health and Health Professions, NY, suggests that - after puberty - the bodies of boys and girls respond differently to caffeine.

We know that caffeine increases blood pressure and decreases heart rate across children, teenagers and adults. In the new study - published in the journal Pediatrics - researchers wanted to see how cardiovascular responses to caffeine might differ between girls and boys following puberty, and also whether the menstrual cycle may influence the effects of caffeine on the cardiovascular system.

Previous research by this team - the first to demonstrate gender differences in physiological response to caffeine in adolescents - had found that boys ages 12-17 report feeling "a greater rush" and more energy from caffeine than girls, as well as improved athletic ability.

That study also found that - as caffeine levels increased - diastolic blood pressure increased and heart rate decreased in boys, but not in girls.

Temple said it isn't clear why boys and girls past puberty react differently to caffeine.

"The data on the girls' menstrual cycles does suggest that the cardiovascular response to caffeine changes along with hormonal fluctuations during menstruation," she told. More research should be done in order to draw stronger conclusions, she said.

Further research could determine whether gender differences in cardiovascular responses to caffeine are related to physiological factors, such as hormonal fluctuations, or psychosocial factors, such as differences in patterns of caffeine consumption among teens.

"While the data suggests that boys and girls respond differently to caffeine, both genders experienced cardiovascular effects of caffeine," she said. "And while it does not suggest that caffeine is particularly harmful to children and adolescents, there is little evidence that caffeine consumption is beneficial to health in this population."