Association of dietary magnesium intake with radiographic knee osteoarthritis: The johnston county osteoarthritis project

Abstract

Purpose.

To examine the cross-sectional association between dietary magnesium (Mg) intake and the radiographic knee osteoarthritis (OA) among African-American and Caucasian men and women.

Methods.

The presence of radiographic knee OA was examined among participants from the Johnston County Osteoarthritis Project (JoCo OA) and was defined as Kellgren-Lawrence (K-L) grade of at least 2 in at least one knee. The Block Food Frequency Questionnaire (FFQ) was used to assess Mg intake. Effect modifiers were explored by testing interactions of Mg intake and selected factors based on previous literature. The multivariable logistic regression model with standard energy adjustment method was used to estimate the relation of Mg intake and radiographic knee OA.

Results.

The prevalence of knee OA was 36.27% among 2112 participants. The relation of Mg intake and radiographic knee OA was found to be modified by race (P for interaction = 0.03). An inverse threshold association was observed among Caucasians. Comparing to those in the lowest quintile, the relative odds of radiographic knee OA was cut by half for participants in the second quintile of Mg intake (OR: 0.52; 95% CI 0.34-0.79); further Mg intake did not provide further benefits (P for trend = 0.51). A statistically significant association was not observed among African Americans.

Conclusion.

A modest inverse threshold association was found between dietary Mg intake and knee OA in Caucasians but not in African Americans. Further studies are needed to confirm the results and to elucidate the possible mechanisms of action for the racial modification. © 2012 by the American College of Rheumatology