Abstract
BACKGROUND: The ratio of calcium-to-magnesium intake (Ca:Mg) may be important for bone due to their competitive absorption. The Ca:Mg ratio has been related to health outcomes, but few studies have related it to bone. OBJECTIVES: The purpose of this analysis was to examine associations between the Ca:Mg intake with bone mineral density (BMD) and osteoporosis among Puerto Rican adults. METHODS: Adults, aged 47-79 y, from the Boston Puerto Rican Osteoporosis Study, with complete BMD and dietary data (n = 955) were included. BMD was assessed with dual-energy X-ray absorptiometry and diet by a food frequency questionnaire. Calcium and magnesium intakes from food were energy adjusted, and the Ca:Mg was calculated. Adjusted linear and logistic regression models were utilized for testing associations between Ca:Mg and bone outcomes. RESULTS: Calcium intake was greater in the highest compared with lowest tertile, whereas magnesium intake was similar across tertiles. Mean BMD at hip sites was higher in the middle, compared with the lowest, tertile. Higher odds of osteoporosis were observed for the highest and lowest tertiles, compared with the middle tertile, after adjustment (T3 compared with T2 OR: 2.79; 95% CI: 1.47, 5.3; T1 compared with T2 OR: 2.01; 95% CI: 1.03, 3.92). Repeated analyses without supplement users (n = 432) led to stronger differences and ORs, but lost significance for some comparisons. CONCLUSIONS: Dietary calcium and magnesium are important for bone, perhaps not independently. The Ca:Mg intake ratio appeared most protective within a range of 2.2-3.2, suggesting that a balance of these nutrients may be considered in recommendations for osteoporosis..