Patients with osteoarthritis who routinely turn to devil’s claw, Indian frankincense, ginger, and other herbal medicines for symptom relief may want to think twice about this practice.
According to a review of these products that appears in the January 2012 issue of Drug and Therapeutics Bulletin, a publication of the London-based BMJ Group, there is little conclusive evidence to justify their widespread use by patients with the disease (Drug Ther. Bull. 2012:50:8-12). A press release about the review points out that few robust studies on the use of herbal medicines for osteoarthritis (OA) have been carried out. "And those that have frequently contain design flaws and limitations, such as variations in the chemical make-up of the same herb, all of which comprise the validity of the findings."
Herbal medicines that are commonly used to treat OA include vegetable extracts of avocado or soybean unsaponifiables (ASUs), cat’s claw, devil’s claw, Indian frankincense, ginger, rosehip, turmeric, and willow bark. According to the review, the best available clinical evidence suggests that ASUs, Indian frankincense, and rosehips may work, "but more robust data are needed." ASUs are available in Europe but not the United States.
"If we did a better job, then patients probably wouldn’t be reaching for herbal medicines."
In an interview, Dr. Roy Altman, professor of medicine at the University of California, Los Angeles, characterized the DTB review as more opinion than an adequate review of the literature. "The reviews of each product were pretty limited; there are longer and more extensive reviews of this topic," said Dr. Altman. Of all the herbals that have been studied as possible agents for OA management, ASUs are supported by the most and best data. "Studies about [ASUs] have been published in several respected journals. The second-best data are with ginger. I don’t think the data with the frankincense and the rosehips are that good, but the rosehips are presently undergoing additional study."
Some herbal medicines may cause adverse reactions in patients taking other medicines and prescription drugs. For example, the chronic use of nettle can interfere with drugs that are used to treat diabetes, lower blood pressure, and depress the central nervous system, whereas willow bark can cause digestive symptoms and renal problems. The review described the use of herbal medicines for OA as "generally under-researched, and information on potentially significant herb-drug interactions is limited."
Although the U.K. Medicines and Healthcare Products Regulatory Agency has approved Traditional Herbal Registrations for several herbal medicinal products containing devil’s claw for rheumatic symptoms, "gthe trial results for this herb are equivocal,"h the review states. "gThere is little conclusive evidence of benefit from other herbs commonly used for symptoms of osteoarthritis, such as cat’s claw, ginger, nettle, turmeric, and willow bark. [Health care] professionals should routinely ask patients with osteoarthritis if they are taking any herbal products."h
Dr. Altman said that he does not currently advocate the use of herbal medicines for OA patients. "We tend to see a lot of patients who ask about frankincense and turmeric," he said. "The major concern we have in this field is not only the approval of these products by some clinical trial basis and the safety of these products, but the verification that the marketed product is consistent from one batch to another. For example, there are about 1,000 different subspecies of ginger. Which of these species are you using, and what time of the year are you harvesting the ginger? The purification process has to be standardized or you’re not going to have the same product from one batch to another. The same problem exists for all of the herbs."
He noted that the review "raises the point that we are not as good at treating OA pain and other problems as we should be. If we did a better job, then patients probably wouldn’t be reaching for herbal medicines."
The review did not include data on glucosamine and chondroitin sulfate, as they are not of herbal origin. Dr. Altman has published research on ginger and has served as a paid consultant in the past with the French company Pharmascience, which manufactures ASUs.