Factors Associated with Calcium Absorption in Postmenopausal Women: a Post-hoc Analysis of Dual Isotope Studies

摘要

Reduced calcium absorption is a risk factor for osteoporosis. This study examined factors associated with fractional calcium absorption (FCA) and net calcium absorption (NCA) in postmenopausal women in a post-hoc analysis of three completed dual isotope studies. Data were analyzed from fifty postmenopausal women undergoing 121 inpatient research visits in three studies evaluating changes in FCA related to correction of vitamin D insufficiency (n=19), use of proton pump inhibitors (n=21) and use of aromatase inhibitors to treat breast cancer (n=10). NCA was the product of FCA and total calcium intake in mg/day. Variables included subjects’ age, race, body mass index, serum calcium, creatinine, parathyroid hormone, 1,25(OH)2D, 25(OH)D and habitual intake of kilocalories, protein, fat, carbohydrate, fiber, calcium, iron, magnesium, oxalate, phosphorus, potassium and vitamin D based on outpatient diet diaries. In multivariate models, subjects’ age, dietary intake of kilocalories, carbohydrates, fat, fiber, calcium and potassium were significant predictors of FCA. In multiple variable models predicting NCA, dietary intake of kilocalories, fat, fiber, calcium, potassium and serum 1,25(OH)2D were significant. The square of the correlation between actual and predicted values (an approximation of R²) was 0.748 for FCA and 0.726 for NCA. Similar to other studies, this study found that age, 1,25(OH)2D and dietary calcium and fat were associated with calcium absorption. Dietary intake of kilocalories, carbohydrates and potassium were new factors that significantly associated with FCA and NCA. In summary, the study suggests that several dietary habits play a role in calcium absorption, beyond vitamin D and calcium.