Association between Dietary Magnesium Intake and Radiographic Knee Osteoarthritis

Objective To examine the cross-sectional associations between dietary magnesium (Mg) intake and radiographic knee osteoarthritis (OA), joint space narrowing (JSN), and osteophytes (OST) respectively. Methods A total of 1626 subjects were included in the study. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. Radiographic knee OA was defined as Kellgren-Lawrence (K-L) Grade 2 in at least one leg. JSN and OST were assessed individually according to the Osteoarthritis Research Society International (OARSI) atlas. A multivariable logistic analysis model was applied to test the various associations after adjusting for potentially confounding factors. Results The relative odds of radiographic knee OA were decreased by 0.53 times in the third quintile of Mg intake [odds ratio (OR) 0.53, 95% confidence interval (CI) 0.28-1.01], 0.40 times in the fourth quintile (OR 0.40, 95% CI 0.17-0.94) and 0.34 times in the fifth quintile (OR 0.34, 95% CI 0.11-1.00) compared with those in the lowest quintile, while P for trend was 0.111. The relative odds of JSN were decreased by 0.49 times in the third quintile of Mg intake (OR 0.49, 95% CI 0.28-0.88) and 0.37 times in the fifth quintile (OR 0.37, 95% CI 0.14-0.98) compared with those in the lowest quintile, while P for trend was 0.088. There was no significant relationship between dietary Mg intake and the presence of OST. Conclusions The findings of this cross-sectional study indicate that Mg intake is inversely associated with radiographic knee OA and JSN. It supports potential role of Mg in the prevention of knee OA.