Nutritional supplements for osteoarthritis evaluated

The 2009 Annual Scientific Meeting of the American College of Rheumatology (ACR) was held in Philadelphia in October. One of the main subjects of the research studies presented during the conference was advances in the management of osteoarthritis as featured in this Medscape report.

Osteoarthritis is the most common form of arthritis characterized by the breakdown of cartilage around the joints. Some of the symptoms are pain, swelling, stiffness, and impairment of motion and function. It affects the joints of the hands, knees, hips or spine. Although the causes of osteoarthritis are poorly understood, studies have identified the risk factors as:

• old age
• female sex,
• high BMI or obesity
• previous trauma
• malalignment
• genetic factors and
• biochemical changes in aging joint tissues

During the ACR meeting, several investigations of nutritional interventions for osteoarthritis were presented. Some of the nutritional therapies are summarized below.

Glucosamine for Knee Osteoarthritis

Glucosamine is a common nutritional supplement used for the management of degenerative joint disease. It is available over the counter. At the ACR meeting, the results of the Joints on Glucosamine (JOG) trial that evaluated the effect of glucosamine on knee osteoarthritis were presented, with disappointing results.

“…no differences were observed in the progression of cartilage lesions between the treatment and placebo arms over the 24-week study. Moreover, glucosamine did not reduce levels of urinary type II collagen fragments, a biomarker for cartilage turnover. Taken together, these data suggest that glucosamine does not inhibit structural progression in knee OA, although this study is limited by its relatively small sample size and short follow-up, especially in light of the fact that OA lesions develop and progress over several years. “

Avocado-soybean unsaponifiables (ASU) for Hip Osteoarthritis

The nutraceutical made from Avocado-soybean unsaponifiables (ASU) is a popular osteoarthritis pain remedy especially in Europe. It is made from extracts of avocado and soybeans.  Results of a 3-year trial that investigated the efficacy of ASU to prevent progression of hip osteoarthritis indicated a weak benefit that needs to be confirmed by more studies.

“At 3 years, no differences were observed between the placebo and ASU-treated groups in the primary outcome, which was change in joint space width. However, a statistically significant 20% reduction in progression, defined as > 0.5 mm reduction in joint space width, was observed in the treatment arm. No effects were observed on patients’ symptoms and ASU was generally well tolerated. Interpretation of the findings from this study is limited by the high patient dropout rate from the study of 41% and a failure to observe a significant difference in the primary outcome. Additional studies are needed to conclusively determine whether ASU has structure-modifying benefits in hip OA and could delay the need for joint replacement procedures.”

Antioxidants

Antioxidants are very popular supplements against cardiovascular diseases. But do they have beneficial effects in inflammatory diseases such as osteoarthritis? Unfortunately, years of study haven’t answered this question. One study reported at ACR meeting

“Higher intake of the antioxidants beta-carotene, vitamins E and C, and selenium were not associated with a reduction in the incidence of severe OA. Surprisingly, an association between high selenium intake and knee and hip OA was observed. This intriguing observation, which could influence how one counsels patients on the use of antioxidant supplements, needs to be confirmed with additional studies.”