title: Dairy, magnesium, and calcium intake in relation to insulin sensitivity: approaches to modeling a dose-dependent association.
abstract: Dairy intake has been inversely associated with insulin resistance, which may be partly due to the specific effects of calcium and magnesium. Data from the Insulin Resistance Atherosclerosis Study (1992-1999) for 1,036 US adults without diabetes at baseline were examined to evaluate the cross-sectional association of habitual dairy, magnesium, and calcium intake with insulin sensitivity at baseline and after 5 years of follow-up. Insulin sensitivity was directly measured with a validated, 12-sample, insulin-enhanced, intravenous glucose tolerance test with minimal model analysis. Dietary intake was assessed by a validated food frequency interview, and dietary supplement dose was confirmed by reviewing the supplement label. Several statistical approaches were used to ensure appropriate modeling of the dose-dependent association. No association was found between dairy intake and insulin sensitivity (p=0.41); however, associations were positive for magnesium and calcium intake (p=0.016) after adjusting for demographic, nondietary lifestyle and dietary factors, and food groups. Furthermore, magnesium intake was associated with insulin sensitivity in a threshold fashion, with a Bayesian method-estimated threshold (325 mg) (beta=0.0607/100 mg, p=0.0008 for <325 mg of magnesium/day; and beta=-0.001/100 mg, p=0.82 for >or=325 mg of magnesium/day). This study suggests that magnesium and calcium intake specifically, but not dairy intake, is associated with insulin sensitivity.
authors.affiliation: Center for Research in Nutrition and Health Disparities, Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC 29204, USA. mab@mailbox.sc.edu
authors.forename: Bo
authors.initials: B
authors.lastname: Ma
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Lawson
authors.forename: Angela D
authors.initials: AD
authors.lastname: Liese
authors.forename: Ronny A
authors.initials: RA
authors.lastname: Bell
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Mayer-Davis
mesh_terms: D000328:Adult; D000368:Aged; D001499:Bayes Theorem; D002118:Calcium / Q000008:administration & dosage* / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D003611:Dairy Products / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004435:Eating; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007333:Insulin Resistance; D008274:Magnesium / Q000008:administration & dosage* / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged
chemical_list: D008274:Magnesium; D002118:Calcium