Most store-bought bottles of Echinacea, ginkgo, St. John's wort and other popular herbal products are filled with unlisted ingredients, contaminants and fillers, found a new study, which quantified just how little consumers often know about products that are supposed to be good for them.
"Contamination and substitution in herbal products present considerable health risks for consumers," the researchers wrote in the journal BMC Medicine. "In our study, we found contamination in several products with plants that have known toxicity, side effects and/or negatively interact with other herbs, supplements, or medications."
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Herbal products generate billions of dollars of income for the companies that produce them, but recent media reports have highlighted the growing problem of false advertising and uncertain ingredients in all sorts of teas, nutraceuticals and medicinal plant supplements.
To investigate the extent of the problem, researchers from the University of Guelph in Canada analyzed the DNA of 44 herbal products made by a dozen companies. Most were capsules. A few were tablets or powders. All were easily accessible at supermarkets, health food stores, pharmacies or websites.