Herbal Supplement Use and Blood Lead Levels of United States Adults

Abstract

Some herbal supplements may contain lead. To examine whether use of specific herbal dietary supplements during the last 30 days is associated with blood lead levels in US men and women. Cross-sectional analysis. NHANES participants from 1999-2004, a representative sample of the civilian non-institutionalized US population. Lead was measured in blood. Associations between lead and self-reported supplement use were estimated using multivariable regression weighted to account for NHANES sampling. Herbal supplements investigated were those previously reported to contain high heavy metal content: Ayurvedic or traditional Chinese medicine herbs, echinacea, ginkgo, ginseng, St. John's wort, and "other" herbs (specifically, kava, valerian, black cohosh, bee pollen, and nettle). Among 6,712 women > or =20 years, those using herbal supplements had lead levels that were 10% higher than non-users (95% CI 3%-17%, p = 0.005). Women using Ayurvedic or traditional Chinese medicine herbs, St. John's wort, and "other" herbs had lead levels 24% (95% CI 5%-45%, p = 0.01), 23% (95% CI 4%-46%), p = 0.02), and 21% (95% CI 2%-44%, p = 0.03) higher, respectively, than non-users. No significant associations were observed between herb use and lead levels among men (n = 6,095). Among reproductive-aged women (16-45 years), herbal supplement users had lead levels 20% higher than non-users (95% CI 5%-34%, p = 0.008). In contrast, garlic and other dietary supplements were not associated with higher lead levels. Use of specific herbal supplements is associated with higher blood lead levels among women. Our data suggest testing guidelines for herbal supplements and regulations limiting lead in supplements are needed.