Association of serum carotenoids, retinol, and tocopherols with radiographic knee osteoarthritis: possible risk factors in rural Japanese inhabitants.

Background: The consumption of antioxidant nutrients may influence the development and progression of osteoarthritis (OA). To determine the association between serum antioxidants and radiographic knee osteoarthritis, we undertook a cross-sectional investigation in a community-based study in Japan.

Methods: A total of 562 subjects (224 male, 338 female) > or = 40 years of age were enrolled in the Comprehensive Health Examination Program (CHEP, Yakumo Study) from 2003 to 2005. Subjects were categorized to the OA group (n = 140) if either knee was graded as Kellgren-Lawrence (K-L) grade > or = 2. The no-OA group was defined as showing radiographic findings of K-L 0 or 1 in either knee (n = 422). The serum levels of retinol, beta-/gamma-tocopherols, alpha-tocopherol, zeaxanthin/lutein, canthaxanthin, cryptoxanthin, lycopene, alpha-carotene, and beta-carotene were measured by high-performance liquid chromatography. The values of these antioxidants were divided into tertiles, and a logistic regression analysis was performed to analyze the association between them and radiographic knee OA, adjusting for potential confounders.

Results: Logistic regression analysis showed that compared to the lowest tertile of beta-/gamma-tocopherols the adjusted odds ratio (OR) was 0.52 [95% confidence interval (CI) 0.29-0.93] in the highest tertile; it also indicated a linear trend across tertiles. Furthermore, the adjusted OR was significantly decreased only in the middle tertile of alpha-tocopherol (OR 0.51, 95% CI 0.29-0.90). We reevaluated any independent association for these tocopherols after adjustment by entering them into the model simultaneously. The significance of beta-/gamma-tocopherols was maintained. In contrast, no associations were found with any carotenoids or retinol.

Conclusions: High serum values of beta-/gamma-tocopherols were found to be significantly associated with a low OR for radiographic knee osteoarthritis. The decreasing risk with a high serum value of beta-/gamma-tocopherols may support the possible protective effects against knee OA.