Qin B et al. – A modest inverse threshold association was found between dietary Mg intake and knee osteoarthritis (OA) in Caucasians but not in African Americans.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.
- 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.