Consuming the popular energy drinks may increase blood pressure and heart rate as well as energy, according to a small study presented at the American Heart Association’s Scientific Sessions held this week in Orlando, Fla.
James Kalus, PharmD, senior manager of Patient Care Services at Henry Ford Hospital in Detroit, presented the findings of his and his colleagues’ research from Wayne State University in Detroit.
While increases did not reach dangerous levels in the healthy volunteers, the increases in blood pressure and heart rate could prove to be clinically significant in patients with heart disease or in those who consume energy drinks often, said Kalus. “Individuals with high blood pressure and heart disease should be advised to avoid these drinks,” he added.
Most energy drinks contain high levels of caffeine and taurine, an amino acid also found in foods with protein. Both have had clinical effects on heart function and blood pressure. In contrast, sports drinks generally contain various mixtures of water, sugars and salts, without chemicals aimed at increasing energy.
The researchers examined 15 healthy young adult participants (53 percent female with an average age of 26), who were asked to refrain from drinking other forms of caffeine for two days prior to and throughout the study. On the first day, measurements of blood pressure, heart rate and electrocardiogram (ECG) were taken. The participants then drank two cans of an energy drink containing 80 mg of caffeine and 1,000 milligrams of taurine.
Researchers then measured blood pressure, heart rate and ECG again at 30 minutes, one, two, three and four hours after consumption, which continued for the next five days. On the seventh day, the researchers followed the same procedures used on the first day.
The researchers compared the average measurements on days one and seven to maximum values.
Within four hours of consumption, maximum systolic blood pressure increased from 7.9 percent on day one to 9.6 percent on day seven; diastolic blood pressure increased from 7 percent to 7.8 percent within two hours of energy drink consumption.
Heart rate increased from 7.8 percent on day one to 11 percent on day seven. Throughout the study, heart rates increased five to seven beats per minute and systolic blood pressure increased 10 mm of mercury after its consumption. No significant ECG changes were observed.
“This occurred while participants were sitting,” Kalus said. “The increases in heart rate and blood pressure weren’t enough for something to happen acutely, but a person on hypertension medication or who has cardiovascular disease may not respond as well.”
The energy drink used in the study had as much caffeine as one to two cups of coffee, and other energy drinks contain much higher levels of caffeine, he said.
Until additional studies occur, Kalus purports that people with high blood pressure or heart disease should avoid energy drinks because they could affect their blood pressure and may alter the effectiveness of their medications.
Wayne State University Undergraduate Research and Creative Projects Grant funded the study.