ALBANY, N.Y. (AP) — The state's attorney general is demanding that 13 manufacturers stop selling an obscure herbal remedy for arthritis called devil's claw because DNA tests found samples contained a plant species different from the plant on their labels.
In letters sent to manufacturers on Wednesday, Attorney General Eric Schneiderman said DNA studies by the New York Botanical Garden found the devil's claw supplements contained a cheaper related species.
Schneiderman said he reached an agreement with a 14th manufacturer, Nature's Way, to improve procedures to ensure its devil's claw contains only the labeled species. Nature's Way also agreed to offer refunds to New York residents who bought devil's claw products after Jan. 1, 2012.
Schneiderman's actions are part of an ongoing investigation of the herbal supplement industry.
Devil's claw is the commercial name for the Kalahari Desert plant Harpagophytum procumbens, which is marketed as a treatment for arthritis and other forms of joint pain. Schneiderman said there have been reports of suppliers mixing devil's claw with a related plant, Harpagophytum zeyheri, or substituting it.
Mark Blumenthal, founder of the American Botanical Council, a nonprofit research and education organization based in Austin, Texas, said the European Pharmocopoeia, which sets standards for medicines and supplements, considers the two species interchangeable. He said devil's claw is "relatively obscure" and sold mainly in health food stores.
"We support the attorney general's concern for consumer welfare, but there's no real public benefit to anything he's doing because the two species are so similar chemically and biologically," Blumenthal said.
Schneiderman's investigation of the herbal products industry started with DNA barcoding tests, which are used to identify something as belonging to a particular species, on some of the most popular herbal supplements, including garlic, ginseng, ginkgo biloba, echinacea and saw palmetto. In February, he ordered four major retailers to stop selling store brand supplements after his office's DNA tests found little or none of the plants on the label.
Industry groups criticized the use of DNA barcoding on those supplements, saying manufacturing processes would have destroyed the DNA but not the active ingredients of the products.
According to an American Botanical Council market report published Wednesday, sales of herbal dietary supplements in the United States increased by 6.8 last year, reaching more than $6.4 billion. Sales were up 12.6 percent for the 52 weeks ending in mid-July of this year compared to a year earlier, the report said.