Dietary supplements at Stiftung Warentest: All unnecessary, some risky. All of the resources are unnecessary, and some are even risky.
No conclusive evidence for any of the products examined that it relieves joint pain or prevents the development of osteoarthritis. Various defects, ranging from minor to serious, were identified in 16 of the 18 products tested. High doses of vitamin E may increase the risk of prostate cancer in men over 55 years of age. Illegal advertising promises were also found on the packaging of some products.