Dietary inflammation index and osteoarthritis in the elderly: is there a mediating role of physical activity?

Wang H, Liao R, Tang W, Su W, Zeng M, Yang J, Fan X, Xie J, Hu Y · The British Journal of Nutrition

The index designed to score a diet's inflammatory potential, applied to osteoarthritis. Compared with the least inflammatory quartile, OA risk rose across quartiles to OR 1.64 (95% CI 1.13-2.37) in the most pro-inflammatory — before adjusting for physical activity. The interesting part is what happened next: physical activity interacted with the index (p < 0.001) and mediated 20% of the association, which the authors read as low activity being part of the pathway rather than a confounder to be removed.

Population

1,249 adults aged 65 and over in NHANES 2011-2016

Intervention

Higher energy-adjusted Dietary Inflammatory Index — a score summarising a diet's inflammatory potential, ranging here from −5.32 to +4.26

Comparator

Lowest quartile of E-DII

Limitations

Cross-sectional NHANES data with self-reported osteoarthritis and diet from a food-frequency questionnaire. The E-DII is a composite score built from nutrient-level inflammatory weights, so it is a construct rather than an exposure anyone can eat. A mediation analysis on cross-sectional data cannot establish the order of events.