Dietary intake of fibre and risk of knee osteoarthritis in two US prospective cohorts

Objectives Dietary fibre reduces body weight and inflammation both of which are linked with knee osteoarthritis (OA). We examined the association between fibre intake and risk of knee OA. Methods We used data from the Osteoarthritis Initiative (OAI) of 4796 participants and Framingham Offspring Osteoarthritis Study (Framingham) of 1268 persons. Dietary intake of fibre was estimated at baseline, and incident radiographic OA (ROA) and symptomatic OA (SxOA) were followed annually until 48 months in OAI and assessed 9 years later in Framingham. Knee pain worsening was also examined in OAI. Generalised estimating equations were applied in multivariable regression models. Results In OAI, we identified 869 knees with SxOA, 152 knees with ROA and 1964 knees with pain worsening among 4051 subjects with valid dietary intake (baseline mean age: 61.2 years; mean body mass index (BMI): 28.6). In Framingham, 143 knees with SxOA and 176 knees with ROA among 971 such subjects (baseline mean age: 53.9 years; mean BMI: 27.0) were identified. In both cohorts, dietary total fibre was inversely associated with risk of SxOA (p trend <0.03) with significantly lower risk at the highest versus lowest quartile (OR (95% CI): 0.70 (0.52, 0.94) for OAI and 0.39 (0.17, 0.88) for Framingham). Furthermore, dietary total and cereal fibre were significantly inversely associated with knee pain worsening in OAI (p trend <0.02). No apparent association was found with ROA. Conclusions Findings from two longitudinal studies consistently showed that higher total fibre intake was related to a lower risk of SxOA, while the relation to ROA was unclear.