Consumers unable to determine if OK to combine supplements with other products, foods
WEDNESDAY, Jan. 9 (HealthDay News) -- One-quarter of supplements sold on military bases fail to meet minimal legal requirements for listing per-serving amounts of caffeine, according to a study published online Jan. 7 in JAMA Internal Medicine.
Pieter A. Cohen, M.D., from Harvard Medical School in Boston, and colleagues identified the most popular dietary supplements sold as capsules (excluding drinks and gels) on military installations. Supplements were labeled as containing either caffeine or one or more herbal ingredient known to naturally contain caffeine but without "caffeine" listed on the label. High-pressure liquid chromatography with ultraviolet absorbance after solvent extraction was used to quantify caffeine per serving in the supplements.
The researchers found that, of the 31 supplements, 20 had caffeine listed on the label, with nine of the 20 having accurate amounts listed. Five of the 20 products listed caffeine amounts that varied widely from the chromatographically determined level (range, 27 to 113 percent of the labeled quantity). Six products that listed caffeine but did not provide amounts contained high amounts of caffeine per serving (210 to 310 mg per serving). Of the 11 supplement labels that listed herbal ingredients containing caffeine, without caffeine explicitly labeled, all listed green tea leaf extract, with three labels including a second caffeine-containing ingredient. These products contained none to minimal amounts of caffeine (0 to 3 mg of caffeine per serving).
"Our chemical analyses of the caffeine content in dietary supplements popular on military bases found that less than half (9 of 20 [45 percent]) of the analyzed supplements' labels provided clinically useful information regarding caffeine content," the authors write.
One author is an employee of NSF International, a nonprofit, nongovernmental organization that developed the U.S. national standards for dietary supplements.