Perhaps the most popular herbal dieting agent on the market today is ephedra, also known by its Chinese name, ma huang. Ephedra has been used for over 5,000 years in China to treat respiratory ailments (3,5,7). About 40 species of the plant are known to be in existence, the most widely used being Ephedra sinica (1,4). The active constituents of the ephedra plant are known as alkaloids. Ephedrine and pseudoephedrine are the main alkaloid compounds derived from ma huang and their amounts vary according to the plant source. These compounds are classified as central nervous system (CNS) stimulants and can be found in some popular over-the-counter drugs and prescribed medications. Ephedrine is used in asthma medications and pseudoephedrine is a component of many nasal decongestants. Ephedrine, while derived from the ma huang plant, may also be produced synthetically (38).

Ephedra and ephedrine alkaloids are thought to enhance weight loss by both decreasing appetite and increasing thermogenesis (the body's ability to expend energy) (22,31,34). Few studies have demonstrated the effectiveness of ephedra alone on weight loss. When ma huang is "stacked" with other stimulants, such as caffeine, the weight loss results appear to be more desirable (22, 23, 24, 26, 27, 29, 31). Nevertheless, side effects may occur from the consumption of ephedra alone. Ma huang may produce the following adverse effects: increased heart rate, increased blood pressure (diastolic and systolic), palpitations, insomnia, nervousness, dizziness and headache (1,10,38). The Food and Drug Administration (FDA) has received over 1,000 complaints of side effects as well as reports of over 50 deaths attributed to the usage of ephedra-containing products (39,40,41). It is therefore advised that people with known heart disease or high blood pressure, diabetes and thyroid disease refrain from taking products containing ephedra or ephedrine alkaloids (3,7,14). Even cases of acute hepatitis and psychiatric illness have been attributed to the use of ephedrine products (13,17). Currently, the FDA recommends no more than 8mg of ephedrine be consumed every six hours with a maximum intake of 24mg per day (1,41). In August of 2000, a public meeting was held by the Department of Health and Human Services to discuss the safety of ephedra (42). The government has since been asked by some of the major ephedra manufacturers to support further research on ephedra (42).

Related to ephedra is the synthetic drug, Phenylpropanolamine (PPA). It is a derivative of ephedrine that is said to produce less CNS stimulation than ephedra (10). PPA can be found in diet aids, such as Dexatrim and in some OTC cough and cold medications, such as Dimetapp. The usage of PPA has been associated with some serious side effects, including heart arrhythmias and hemorrhagic strokes (10,43). In October of 2000, the FDA announced to the public that the dangers of PPA products warranted immediate discontinuation of their production and is taking steps to ban the substance entirely. It is likely that the FDA will demand that these products be pulled off the market soon. Some major drug stores have already voluntarily removed products containing PPA from their shelves.

Caffeine