title: Factors associated with calcium absorption in postmenopausal women: a post hoc analysis of dual-isotope studies.
abstract: Reduced calcium absorption is a risk factor for osteoporosis. This study examined factors associated with fractional calcium absorption (FCA) and net calcium absorption in postmenopausal women in a post hoc analysis of three completed dual-isotope studies. Data were analyzed from 50 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). Net calcium absorption was the product of FCA and total calcium intake in milligrams per day. Variables included subjects' age, race, body mass index, serum calcium, creatinine, parathyroid hormone, 1,25-dihydroxyvitamin D, 25-hydroxyvitamin 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 net calcium absorption, dietary intake of kilocalories, fat, fiber, calcium, potassium, and serum 1,25-dihydroxyvitamin D were significant. The square of the correlation between actual and predicted values (an approximation of R(2)) was 0.748 for FCA and 0.726 for net calcium absorption. Similar to other studies, this study found that age, 1,25-dihydroxyvitamin D, and dietary calcium and fat were associated with calcium absorption. Dietary intake of kilocalories, carbohydrates, and potassium were new factors that were significantly associated with FCA and net calcium absorption. In summary, the study suggests that several dietary habits play a role in calcium absorption, beyond vitamin D and calcium.
authors.forename: Karishma
authors.initials: K
authors.lastname: Ramsubeik
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Keuler
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Davis
authors.forename: Karen E
authors.initials: KE
authors.lastname: Hansen
mesh_terms: D000368:Aged; D015992:Body Mass Index; D002136:Calcium, Dietary / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004043:Dietary Fiber / Q000008:administration & dosage; D002149:Energy Intake; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008875:Middle Aged; D015596:Nutrition Assessment; D010281:Parathyroid Hormone / Q000097:blood; D017698:Postmenopause / Q000378:metabolism*; D017419:Potassium, Dietary / Q000008:administration & dosage; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D002136:Calcium, Dietary; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004043:Dietary Fiber; D010281:Parathyroid Hormone; D017419:Potassium, Dietary; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D; D003404:Creatinine
keywords: Calcium absorption; Calories; Fat; Fiber; Postmenopausal women