What is Ephedra and Why Do People Use It?
The herb ephedra, also known as ma huang, is a small, twiggy shrub native to Asia, where it has a long history of medicinal use, as documented in ancient medical treatises from India and China. Traditional Chinese and Indian medicine uses the branches of the herb to treat colds and wheezing and as a diuretic. Modern European practitioners of herbal medicine use ephedra only to treat symptoms of respiratory diseases (such as bronchial asthma).
In the United States, the active components of ephedra, known as the ephedrine alkaloids (ephedrine; pseudoephedrine; norephedrine, also known as phenylpropanolamine; and norpseudoephedrine) are commonly found in over-the-counter cold and allergy medications. The ephedrine alkaloids are stimulants (similar to, but much weaker than, amphetamines) that can increase heart rate and blood pressure and relax bronchial tissue, easing shortness of breath. At low doses, they are reputed to decrease appetite, increase alertness and productivity, improve mood, and decrease fatigue; at higher doses, they may promote anxiety, restlessness, and insomnia.
The use of ephedra to promote weight loss and enhance athletic performance began to gain popularity in the United States in the early 1990s. The increase in popularity of herbal products and over-the-counter medications that seem to promote weight loss is probably attributable to a combination of factors, including the recent precipitous rise in overweight and obesity rates, news stories suggesting that prescription diet drugs may be dangerous, the reluctance of many overweight people to talk with their doctors about weight control, and the growing belief on the part of many people that natural substances such as herbs (and those perceived as natural) are safer than mainstream medicines.
People have used dietary supplements to enhance athletic performance for many years. Use of dietary supplements and over-the-counter medications containing stimulants like ephedrine to enhance athletic performance increased throughout the latter part of the 20th century, perhaps in part because of the bans imposed on use of amphetamines and because of the accelerating intensity of competitive sports.
What We Did (and Why)
Our assessment of the evidence was guided by a distinguished panel of technical experts, both basic scientists and clinicians. This group included cardiologists, exercise physiologists, pharmacologists, and toxicologists, as well as specialists in obesity, nutrition, and the science of pharmacognosy. The technical expert panel recommended that we also review studies of over-the-counter medications that contain the chemical ephedrine, presumed to be the primary active ingredient of ephedra (ephedrine-containing products are regulated as pharmaceuticals, not as dietary supplements). In addition, many ephedracontaining supplements also include herbs that contain caffeine, and products that contain ephedrine often include caffeine. Because caffeine is believed to have effects that are similar to ephedrine, such combinations could potentially be more powerful than either substance alone. Thus, we were also asked to review the evidence for the effectiveness and safety of supplements that combine ephedra and caffeine as well as ephedrine and caffeine-containing products.
To assess the evidence for the effectiveness of ephedra and ephedrine in weight loss and athletic performance, we performed an exhaustive search and review of the medical research "literature" using the well-accepted procedures of evidence-based medicine. The literature review was conducted by our staff with the assistance of several clinical experts.
Only controlled clinical trials and randomized controlled trials of effectiveness—that is, studies that satisfied a strict set of quality criteria—were included in our analysis. Randomized controlled trials (RCT) are clinical trials in which participants are assigned randomly to one of two or more treatment groups. Controlled clinical trials are those in which participants are assigned to a treatment group using a semi-random procedure (such as a participant's date of birth, a patient identification number, or the order of enrollment). In all, we reviewed the results of 52 clinical trials that measured the effects of ephedra or ephedrine on weight loss and athletic performance. Most of these studies included one group of participants who were randomly chosen to receive only a placebo (an inactive dummy pill). This type of study maximizes the likelihood that any differences found between the groups taking the test supplement and those taking the placebo are real, not due to chance or bias.
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