Association between a Calcium-to-Magnesium Ratio and Osteoporosis among Puerto Rican Adults.

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..

Effect of intratrial mean 25(OH)D concentration on diabetes risk, by race and weight: an ancillary analysis in the D2d study.

BACKGROUND: Higher serum 25-hydroxyvitamin D [25(OH)D] is associated with lower type 2 diabetes risk. 25(OH)D varies due to skin pigmentation and weight. OBJECTIVES: This analysis aims to determine whether the effect of vitamin D differs among people of color and those with overweight/obesity (who have higher diabetes risk) compared with individuals who are White or have normal weight. METHODS: The D2d study is a randomized clinical trial in people with prediabetes that tested the effects of daily vitamin D3 4000 IU vs. placebo on diabetes risk (median followup 2.5 y). We compared baseline and intratrial mean 25(OH)D concentrations, defined as the mean of all available annual 25(OH)D values, among groups defined by self-reported race and body mass index (BMI). We used Cox proportional hazards models to assess the associations between intratrial mean 25(OH)D and diabetes risk by race- and BMI-based groups. RESULTS: Asian (n=130), Black (n=616), and White (n=1616) participants were included. Both baseline and intratrial mean 25(OH)D concentrations differed significantly by race groups (both P < 0.001) and were lower in Asian and Black vs. White participants, and in those with higher vs. lower BMI adjusted for race (both P < 0.001). Compared with those with lower concentrations, Black and White participants with intratrial mean 25(OH)D ≥ 40 ng/mL had significantly reduced diabetes risk [HR (95% CI): Black: 0.51 (0.29, 0.92); White: 0.42 (0.30, 0.60)] and with a similar reduction in diabetes risk among Asian participants: 0.39 (0.14, 1.11). Compared with those with lower concentrations, participants with baseline BMI < 40 kg/m2 who achieved intratrial mean 25(OH)D concentrations ≥ 40 ng/mL had a significantly reduced diabetes risk. There was no statistically significant interaction between intratrial 25(OH)D and race or between intratrial 25(OH)D and BMI on diabetes risk. CONCLUSIONS: Among people with prediabetes, particularly for Black and White race groups and those with BMI < 40 kg/m2, the optimal 25(OH)D concentration may be ≥ 40 ng/mL to optimize diabetes-prevention efforts. This trial was registered at clinicaltrials.gov as NCT01942694.