Results from the Women’s Health Initiative Observational Study
American Journal of Clinical Nutrition, 02/10/2014 Review Article
Orchard TS, et al. – The authors examined magnesium intake as a risk factor for osteoporotic fractures and altered bone mineral density (BMD). Lower magnesium intake is associated with lower BMD of the hip and whole body, but this result does not translate into increased risk of fractures. A magnesium consumption slightly greater than the Recommended Dietary Allowance is associated with increased lower–arm and wrist fractures that are possibly related to more physical activity and falls.
Methods
- This prospective cohort study included 73,684 postmenopausal women enrolled in the Women’s Health Initiative Observational Study.
- Total daily magnesium intake was estimated from baseline food-frequency questionnaires plus supplements.
- Hip fractures were confirmed by a medical record review; other fractures were identified by self-report.
- A baseline BMD analysis was performed in 4778 participants.
Results
- Baseline hip BMD was 3% higher (P < 0.001), and whole-body BMD was 2% higher (P < 0.001), in women who consumed >422.5 compared with <206.5 mg Mg/d.
- However, the incidence and RR of hip and total fractures did not differ across quintiles of magnesium.
- In contrast, risk of lower-arm or wrist fractures increased with higher magnesium intake [multivariate-adjusted HRs of 1.15 (95% CI: 1.01, 1.32) and 1.23 (95% CI: 1.07, 1.42) for quintiles 4 and 5, respectively, compared with quintile 1; P-trend = 0.002].
- In addition, women with highest magnesium intakes were more physically active and at increased risk of falls [HR for quintile 4: 1.11 (95% CI: 1.06, 1.16); HR for quintile 5: 1.15 (95% CI: 1.10, 1.20); P-trend < 0.001].