Dietary intake of fiber and risk of knee osteoarthritis in two U.S. prospective cohorts

Authors: DAI, ZHAOLI - Boston University; NIU, JINBGO - Boston University; ZHANG, YUQING - Boston University; JACQUES, PAUL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; FELSON, DAVID - Boston University

Submitted to: Annals of the Rheumatic Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2017
Publication Date: 5/26/2017
Citation: Dai, Z., Niu, J., Zhang, Y., Jacques, P.F., Felson, D.T. 2017. Dietary intake of fiber and risk of knee osteoarthritis in two U.S. prospective cohorts. Annals of the Rheumatic Diseases. doi: 10.1136/annrheumdis-2016-210810.

Interpretive Summary: Dietary fibers are carbohydrates, primarily from plant-based foods such as grains, legumes, fruits and vegetables, which are not digested or absorbed in the small intestine but are partially or fully fermented in the large intestine. A growing body of epidemiologic studies suggests that fiber may reduce risks of cardiovascular diseases, type 2 diabetes, and total mortality. Dietary fiber may confer health benefits by helping to regulate body weight, lower inflammation, reduce serum cholesterol, and improve glycemic control. Osteoarthritis (OA) is the most common joint disorder and is highly prevalent among adults aged 60 years and above. Largely due to pain and limited physical function, OA is a leading cause of disability and impairment of quality of life. As a major risk factor for knee OA, obesity both increases loading and inflammation in weight-bearing joints. Dietary fiber reduces chronic inflammation related to obesity. In light of the causal relation of dietary fiber to body weight and inflammation, we assessed the association between dietary fiber and knee OA, including symptomatic and radiographic knee OA and knee pain worsening in two U.S. cohorts. We used data from the Osteoarthritis Initiative (OAI) and Framingham Offspring Osteoarthritis Study (Framingham.) In both studies, dietary intake of fiber was estimated at baseline and incident radiographic (ROA) and symptomatic OA (SxOA) were followed annually until 48 months in OAI and assessed 8 years later in Framingham. Knee pain worsening was also examined in OAI. In OAI, we identified 861 knees with SxOA, 152 knees with ROA, and 1,964 knees with pain worsening among 4,051 eligible subjects (baseline mean age: 61y; mean BMI: 28.6). In Framingham, 143 knees with SxOA and 175 knees with ROA among 971 eligible subjects (baseline mean age: 54y; mean BMI: 27.0) were identified. In both cohorts, higher dietary fiber intake was associated with a lower risk of SxOA. Furthermore, higher intakes of total dietary fiber and cereal fiber were associated with less worsening of knee pain in OAI. No association was found between fiber intake and ROA. Findings from two longitudinal studies consistently showed that higher total fiber intake was related to a lower risk of symptomatic knee OA, while the relation to radiographic OA was unclear, suggesting that dietary fiber may have a beneficial role in reducing OA.

Technical Abstract: Objectives: Dietary fiber reduces body weight and inflammation both of which are linked with knee osteoarthritis (OA). We examined the association between fiber 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. In both studies, dietary intake of fiber was estimated at baseline and incident radiographic (ROA) and symptomatic OA (SxOA) were followed annually until 48 months in OAI and assessed 8 years later in Framingham. Knee pain worsening was also examined in OAI. Generalized Estimating Equations were applied in multivariable regression models. Results: In OAI, we identified 861 knees with SxOA, 152 knees with ROA, and 1,964 knees with pain worsening among 4,051 eligible subjects (baseline mean age: 61.2y; mean BMI: 28.6.)" In Framingham, 143 knees with SxOA and 175 knees with ROA among 971 eligible subjects (baseline mean age: 53.9y; mean BMI: 27.0) were identified. In both cohorts, dietary total fiber was inversely associated with risk of SxOA (p-trend <0.02) 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 fiber were significantly inversely associated with knee pain worsening in OAI (p-trend<0.02). No association was found with ROA. Conclusions: Findings from two longitudinal studies consistently showed that higher total fiber intake was related to a lower risk of symptomatic knee OA, while the relation to radiographic OA was unclear.