Originally researchers found healthy adults who drank two cans of a popular energy drink a day had above normal blood pressure and heart rate. Though the observed heart rate and blood pressure increases were not dangerous for healthy volunteers, the results suggest that there could be dangers for patients with heart disease.
Energy drinks differ from sports drinks because they contain high levels of caffeine and taurine to increase "energy levels" or alertness. Similar to caffeine, taurine has been shown to increase blood pressure and heart rate.
During the study, researchers required 15 healthy young adult volunteers to have their blood pressure and heart rate measured. The volunteers then drank two energy drinks, containing 80 milligrams of caffeine and 1,000 milligrams of taurine, each day for 7 days. The results showed that within 4 hours of consuming the energy drink, the maximum systolic blood pressure rose 7.9 percent on day 1 and 9.6 percent on day 7. Heart rate was found to increase 7.8 percent on day 1 and 11 percent on day seven.
Researchers were unsure what effect combining exercise with energy drinks might have. They warned that blood pressure and heart rate naturally rises with exercise and energy drinks could raise their levels even further.
Now a host of new studies have appeared that further delineate the risks associated with these high energy drinks.
These new documented risks include:
• Dental decay. High energy drinks have the potential to erode tooth enamel more quickly than sodas, sports drinks and and other sweetened beverages.
• Energy highs and crashes. One study reported that 29 percent of college students experience weekly jolt and crash episodes from energy drinks.
• Headaches and heart palpitations. 22 percent of college students studied in the same research reported having headaches, and 19 percent had heart palpitations after drinking the energy drinks.
• Poor perception of intoxication. Mixing an alcoholic beverage with an energy drink reduces one’s ability to discern one’s own discernment as to whether he or she is intoxicated. Intoxication does reduce one’s ability to make good judgments, but at least one usually can tell that he or she is drunk. But by adding an energy drink to one’s alcohol the feeling of intoxication is masked and thus only increases the opportunity for making poor decisions – such as driving when impaired.
• Higher risk of injury. Along these lines a study done by a Wake Forest research group confirmed the higher incidences of injury to college students after mixing energy drinks with alcohol.
• Increased risk taking. Consume six or more energy drinks a month, and you are also at three times greater risk of smoking cigarettes, abusing prescription drugs, or engaging in a serious physical fight. In other words, energy drink consumption goes along with other risky behaviors and one is probably an indicator of the other – such as alcohol, marijuana or cocaine abuse.
Researchers at Johns Hopkins University called for prominent labels to warn consumers of the possible dangers of energy drinks. "The caffeine content of energy drinks varies over a 10-fold range, with some containing the equivalent of 14 cans of Coca-Cola," says Roland Griffiths, Ph.D., a co-author off an article published in Drug and Alcohol Dependence. "Yet the caffeine amounts are often unlabeled and few include warnings about the potential health risks of caffeine intoxication."
Caffeine content in energy drinks range between 50 and more than 500 milligrams (for a 12-ounce cola drink it's 35 milligrams, and it's about 80 to 150 milligrams for a brewed 6-ounce cup of coffee). However, energy drinks are marketed as "dietary supplements" and the Food and Drug Administration's caffeine content limit of 71 milligrams per 12-ounce can doesn't apply.