The Reply

Abstract

We appreciate Mr. McGuffin’s interest in our clinical study findings on bitter orange (Citrus aurantium). In regard to the observed effect on heart rate, although it is well known that heart rate fluctuates with normal daily activities, including eating, the observed mean peak heart rate increases observed with bitter orange alone and bitter orange-plus-caffeine were approximately 2-fold higher than the heart rate increase observed with placebo. This difference was statistically significant. The clinical importance of this magnitude change in heart rate would depend on the individual and the setting. It should be noted that the observed increases in heart rate occurred while subjects were at rest. The heart rate-accelerating effects of bitter orange, alone or with caffeine, have not been evaluated in the setting of exercise or in individuals with medical conditions such as hypertension or coronary artery disease. Furthermore, a heart rate-accelerating effect of bitter orange when combined with the vasoconstrictor actions of another constituent, such as caffeine, could result in a substantially greater increase in blood pressure compared with that seen with the vasoconstrictor alone. Further studies are needed to adequately assess the safety of stimulant herbal combinations in people who are likely to use these products, particularly obese and poorly fit individuals.A wide range of weight-loss supplements are currently on the market. A stroll down any dietary supplement store aisle confirms that a bewildering variety of weight-loss supplements are available to consumers. Diligent attempts to make an informed buying decision are hindered by vague product labeling, such as multi-ingredient “proprietary blends,” that provides no information on the content or dose of active constituents. It is gratifying to learn that the American Herbal Products Association now recommends specific labeling of supplements containing caffeine. We hope such recommendations will be extended to all weight-loss products that contain sympathomimetic herbal ingredients. We appreciate Mr. McGuffin’s interest in our clinical study findings on bitter orange (Citrus aurantium). In regard to the observed effect on heart rate, although it is well known that heart rate fluctuates with normal daily activities, including eating, the observed mean peak heart rate increases observed with bitter orange alone and bitter orange-plus-caffeine were approximately 2-fold higher than the heart rate increase observed with placebo. This difference was statistically significant. The clinical importance of this magnitude change in heart rate would depend on the individual and the setting. It should be noted that the observed increases in heart rate occurred while subjects were at rest. The heart rate-accelerating effects of bitter orange, alone or with caffeine, have not been evaluated in the setting of exercise or in individuals with medical conditions such as hypertension or coronary artery disease. Furthermore, a heart rate-accelerating effect of bitter orange when combined with the vasoconstrictor actions of another constituent, such as caffeine, could result in a substantially greater increase in blood pressure compared with that seen with the vasoconstrictor alone. Further studies are needed to adequately assess the safety of stimulant herbal combinations in people who are likely to use these products, particularly obese and poorly fit individuals. A wide range of weight-loss supplements are currently on the market. A stroll down any dietary supplement store aisle confirms that a bewildering variety of weight-loss supplements are available to consumers. Diligent attempts to make an informed buying decision are hindered by vague product labeling, such as multi-ingredient “proprietary blends,” that provides no information on the content or dose of active constituents. It is gratifying to learn that the American Herbal Products Association now recommends specific labeling of supplements containing caffeine. We hope such recommendations will be extended to all weight-loss products that contain sympathomimetic herbal ingredients. Effect on Heart Rate of Bitter Orange, Caffeine, and ExerciseThe American Journal of MedicineVol. 120Issue 1Preview In the September 2005 issue of the Journal, Haller et al reported on the cardiovascular effects of a supplement product containing bitter orange (Citrus aurantium) extract alone and one containing bitter orange with other ingredients, including at least one source of caffeine.1 (Nutratech, Inc., the marketers of Advantra Z, which was studied in Dr. Haller’s report, is a member of the American Herbal Products Association, of which I am president. The American Herbal Products Association is a national trade association and voice of the herbal products industry.) This randomized, double-blind, placebo-controlled, crossover study with 10 subjects concluded that bitter orange extract, when consumed alone and apparently at 3 times the dosage recommended on the test product’s label, “had no effect on blood pressure,” a result that also has been reported in other recent studies. 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