Energy drink increases blood pressure, norepinephrine levels

Anna Svatikova, M.D., Ph.D., of the Mayo Clinic, Rochester, Minn., and colleagues randomly assigned 25 healthy volunteers (age 18 years or older) to consume a can (480 mL; 16 fl. oz.) of a commercially available energy drink (Rockstar; Rockstar Inc) and placebo drink within 5 minutes, in random order on 2 separate days, maximum 2 weeks apart. The placebo drink, selected to match the nutritional constituents of the energy drink, was similar in taste, texture, and color but lacked caffeine and other stimulants of the energy drink (240 mg of caffeine, 2,000 mg of taurine, and extracts of guarana seed, ginseng root, and milk thistle). This JAMA study is being released to coincide with its presentation at the American Heart Association's Scientific Sessions 2015.

08 nov 2015--Energy drink consumption has been associated with serious cardiovascular events, possibly related to caffeine and other stimulants. The researchers examined the effect of energy drink consumption on hemodynamic changes, such as blood pressure and heart rate. Participants were fasting and abstained from caffeine and alcohol 24 hours prior to each study day. Serum levels of caffeine, plasma glucose, and norepinephrine (noradrenaline) were measured and blood pressure and heart rate were obtained at baseline and 30 minutes after drink ingestion.
Caffeine levels remained unchanged after the placebo drink, but increased significantly after energy drink consumption. Consumption of the energy drink elicited a 6.2 percent increase in systolic blood pressure; diastolic blood pressure increased by 6.8 percent; average blood pressure increased after consumption of the energy drink by 6.4 percent. There was no significant difference in heart rate increase between the 2 groups. The average norepinephrine level increased from 150 pg/mL to 250 pg/mL after consumption of the energy drink and from 140 pg/mL to 179 pg/mL after placebo (change rate: 74 percent vs 31 percent, respectively).
"These acute hemodynamic and adrenergic changes may predispose to increased cardiovascular risk," the authors write. "Further research in larger studies is needed to assess whether the observed acute changes are likely to increase cardiovascular risk."

More information: DOI: 10.1001/jama.2015.13744


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AHA: Energy Drinks Amp Up Blood Pressure


ORLANDO, Nov. 7 -- Energy drinks boost blood pressure in even the young and healthy people and may leave hypertensive adults more charged up than they bargained for, researchers said here.
Action Points
Explain to interested patients that the study suggests that energy drinks may not be recommended for patients with hypertension and other cardiovascular disease.
Note that this study was published as an abstract and presented orally at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed publication.
Consumption of two energy drinks a day increased systolic blood pressure by 10 mm Hg and heart rate by five to seven beats per minute, according to a small study reported at the American Heart Association meeting.
Although this degree of change may hold little danger for most young patients, it likely would be clinically significant with regular consumption or in patients with cardiovascular disease such as hypertension, said James S. Kalus, Pharm.D., of the Henry Ford Medical Center in Detroit, Mich., and colleagues.
"If you know you have cardiovascular disease or are taking medication to lower blood pressure, it is important to avoid energy drinks until we learn more about what they do," he said.
Energy drinks typically contain high levels of caffeine and the amino acid taurine. These compounds have been shown in previous studies to have an impact on cardiac function and hemodynamic status, although the data available for caffeine are controversial, Dr. Kalus said.
The study included 15 healthy volunteers (53% women) with an average age of 25.9 who abstained from caffeine for two days before and during the study.
After participants' blood pressure and heart rate were measured and an electrocardiogram was taken at baseline, they drank two cans of an energy drink containing 80 mg caffeine and 1,000 mg taurine. The same tests were repeated at 30 minutes, and at one, two, three, and four hours after consumption while the volunteers sat around watching movies.
The men and women drank two cans a day for the following five days with another regimen of testing on the last day.
Diastolic blood pressure peaked two hours after administration with a 7% elevation on day one (P=0.046) and 7.8% elevation on day seven (P=0.063). The other measures all peaked at four hours after consumption.
The four-hour changes on days one and seven, respectively, included:
Systolic blood pressure increased by 7.9% (P=0.006) and 9.6% (P0.001).
Heart rate rose by 7.8% (P=0.009) and 11.0% (P0.001)
Corrected QT-interval tended to increase by 4.5% (P=0.368) and 5.5% (P=0.052).
Although some data suggest tolerance can develop to the caffeine in coffee, no blunting of the energy drink effects was seen over the seven days, Dr. Kalus said. However, a week might be too short a period for that to be noticeable, he added.
The brand of energy drink used in the study contained the caffeine equivalent of two cups of coffee, but it's not clear whether the other compounds in it such as sugar and B vitamins contributed to the effect, he said.
Nevertheless, the main compounds implicated in the cardiovascular alterations -- caffeine and taurine -- are consistent ingredients across brands. This suggests the findings are likely generalizable across energy drinks, though not to sports drinks, which typically do not have caffeine, Dr. Kalus said.
The study was supported by the Wayne State Undergraduate Research Fund. Dr. Kalus reported no conflicts of interest.
Primary source: American Heart Association meetingSource reference: Steinke L, et al "'Energy Drink' Consumption Causes Increases in Blood Pressure and Heart Rate" AHA meeting 2007; Abstract 3661.