SAN DIEGO--Additional research has emerged demonstrating the potential for adverse cardiovascular events from taking an ephedra/caffeine combination before exercise. Tasha P. Ballard and Matthew D. Vukovich, Ph.D., FACSM, both from South Dakota State University in Brookings, presented a study at the American Physiological Society's (www.the-aps.org) Experimental Biology 2003, held here April 11 to 15, demonstrating that the combination of ephedra and caffeine, taken prior to exercise, places greater stress on the heart than placebo by affecting the cardiovascular system before, during and after exercise.
Vukovich conducted a resting study prior to his exercise study and determined ephedra/caffeine places additional stress on the cardiovascular system even without exercise. "During the resting study, we saw a 23-percent increase in heart rate and 10-percent increase in blood pressure," he told INSIDER. "The concern was, while exercise increases heart rate and blood pressure and caffeine/ephedra increases heart rate and blood pressure, what happens when people take them together, which most people do?"
To determine what would happen, Ballard and Vukovich randomly assigned 10 healthy, college-age subjects (five men and five women) who were free of caffeine to either a one-time dose of placebo or a combination of 150 mg of caffeine plus 20 mg of ephedra. After a week washout period, the subjects reversed treatments. Researchers recorded the subjects' key physiological measurements--blood pressure, VO2 (oxygen consumption, which helps researchers calculate resting metabolic rate and caloric expenditure) and hypersensitive response--prior to and 30 and 60 minutes after supplement administration.
Results indicated hypersensitive response was higher at 60 minutes rest in subjects that received the combination, and remained higher at 30 and 60 minutes of exercise. However, this increase does not warrant using ephedra/caffeine for weight loss, according to Vukovich. "It's only a 100 kcal difference--equivalent to walking for 15 minutes," he said. "Then you have to look at the risk-to-benefit ratio. Granted, it may increase resting metabolic rate, but you get a greater increase in heart rate and blood pressure, and overweight individuals have high blood pressure as it is."
In addition to the increased hypersensitive response, researchers found those taking the supplements exhibited higher systolic blood pressure during rest. Mean arterial pressure (the driving pressure of blood flow through the body) measured higher in the treatment group, as well. "Based on the results we've gotten out of our lab, to me there is no reason to take [ephedra-based supplements]," Vukovich said.
Michael McGuffin, president of the American Herbal Products Association, noted that while Vukovich's study demonstrated the effects likely to be seen from using the available ephedra/caffeine supplements on the market, the research did not take into account how big a role each of the components played in affecting cardiovascular function. "We don't know what role ephedra played in this, compared to what role caffeine played in this," he said. "If these authors, or the journal in which they publish, intend to make this an 'ephedra is bad' news story, there's a problem with that. Caffeine has exactly the same effects [as ephedra]. The next study should compare caffeine alone and ephedra alone--then we'd see a meaningful scientific inquiry that would be useful for better understanding the physiological effects of ephedra."
In additional ephedra news, due to the potentially dangerous cardiovascular side effects of ephedra consumption, the American Heart Association (AHA) submitted comments to the Food and Drug Administration (FDA) April 3 urging a ban of ephedra-based supplements. Robert O. Bonow, M.D., AHA president, stated the evidence against ephedra supplements indicates the dangers are greater than the potential benefits, and while consumers who use ephedra-based supplements may think they are doing something healthy, they may be putting themselves at risk.
Bonow stated the only way to protect consumers from these "dangerous" supplements is to ban them completely. "Unfortunately, experience tells us that there is a tendency for the public to ignore warning labels and dosage information," he said. "Because of the uncertainty surrounding these products, we believe it is necessary to completely eliminate that risk."
McGuffin noted that consumer responsibility plays a large role in the debate surrounding ephedra. "Some of the concern is that ephedra is a physiologically active stimulant," he said. "That means it should bear a warning label. The Dietary Supplement Health and Education Act (DSHEA) is, on its face, a consumer right-to-know law. We continue to believe consumers have a right to know and to make choices, which does involve some responsibility. Consumers need to read the label and believe the label. ... That's our challenge--to make consumers believe that a warning label means 'warning.'"