Abstract
BackgroundTo examine the relation between inflammatory potential of diet and incident knee osteoarthritis (OA) and the role of BMI in the association of interest.MethodsIn the Osteoarthritis Initiative, the energy-adjusted dietary inflammatory index (E-DII™) scores were calculated based on the Block Brief 2000 Food Frequency Questionnaire and categorized into sex-specific quartiles. Outcomes were incident (1) radiographic knee OA (ROA) (i.e., a KL grade ≥ 2) and (2) symptomatic knee OA (SxOA) (i.e., a combination of frequent knee pain and ROA). We fitted generalized estimating equation models to examine the association between E-DII scores and incident knee OA. We performed mediation analyses to assess the potential mediation by BMI in the DII-OA relation.ResultsOver a 48-month follow-up period, 232 and 978 knees developed ROA and SxOA, respectively. Compared with the lowest (most anti-inflammatory) E-DII quartile, the odds ratio (OR) of incident ROA for the highest (most pro-inflammatory) E-DII quartile was 1.73 (95% confidence interval (CI) 1.15 to 2.62, Ptrend = 0.007). The corresponding OR for SxOA was 1.43 (95% CI 1.16 to 1.76, Ptrend = 0.001). The DII-OA association was significantly mediated via BMI with an indirect effect of 1.08 (95% CI 1.04, 1.13) for ROA and 1.13 (95% CI 1.09, 1.16) for SxOA, accounting for 20.4% and 44.5% of the total effect, respectively.ConclusionsA higher inflammatory potential of diet increased the risk of knee OA. The association was significantly mediated via BMI. Targeting the inflammatory potential of diet may be beneficial to reduce the risk of knee OA.
Highlights
To examine the relation between inflammatory potential of diet and incident knee osteoarthritis (OA) and the role of body mass index (BMI) in the association of interest
Among participants included in the analysis of incident radiographic knee OA (ROA) or Symptomatic knee OA (SxOA), subjects in the highest E-Dietary inflammatory index (DII) quartile (Q4, reflecting the most pro-inflammatory diet) were younger, more likely to have attained college or higher educational level, and had an annual income ≥ 50,000 US$ as well as a higher total energy intake and BMI than their counterparts in the lowest quartile of Energy-adjusted DII (E-DII) (Q1, representing the most anti-inflammatory diet)
BMI significantly mediated the effect of E-DII on incident ROA, comparing participants with an E-DII < median (i.e., 2.50) with those whose E-DII ≥ median (OR for indirect effect = 1.08, 95% Confidence interval (CI) 1.04 to 1.13), with a proportion of mediation of 20.4%
Summary
To examine the relation between inflammatory potential of diet and incident knee osteoarthritis (OA) and the role of BMI in the association of interest. Liu et al Arthritis Research & Therapy (2020) 22:209 that interact with one another and exert inflammatory potential as a whole; it is reasonable to use a summary measure to quantify the inflammatory potential of diet as a whole In this sense, a dietary index that summarizes the functional effect of food has an advantage over examining single dietary components in the study of diet-disease associations [16]. A recent study showed that adjustment for BMI substantially attenuated the association of dietary fiber with the risk of symptomatic knee OA (SxOA) [19] Taken together, these findings suggest that BMI may function as a mediator in the association between the inflammatory potential of diet and knee OA. Such a hypothesis has not been formally tested yet
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