title: Vitamin C and A1c relationship in the National Health and Nutrition Examination Survey (NHANES) 2003-2006.
abstract: OBJECTIVE
  The scope of the diabetes epidemic stresses the critical need for primary prevention. The consumption of foods high in vitamin C has been associated with lower risk of diabetes. The aim of this study was to analyze the relation between vitamin C concentration and glycemic control index in a large sample of U.S. adults without a history of diabetes.
  
  
  METHODS
  We analyzed data collected from 7697 adult participants in the National Health and Nutrition Examination Survey (NHANES) 2003-2006 who did not report a history of diabetes. Multivariate linear regression analyzed the association of vitamin C and hemoglobin A1c (A1c) levels after accounting for potential confounders. We also conducted stratified analyses based on race/ethnicity, gender, age group, body mass index, and vitamin D status.
  
  
  RESULTS
  Vitamin C concentrations were inversely associated with A1c (p = 0.0202). Stronger inverse associations were observed in subjects 18-44 years of age (p = 0.0017), as well as in female (p = 0.0035) and Mexican American (p = 0.0149) subgroups. Evidence of a significant interaction between vitamin C and vitamin D was noted in subjects aged 18-44 years and in females (p = 0.0073 and 0.0095 respectively), with the inverse association tending to be evident at lower levels of vitamin D.
  
  
  CONCLUSIONS
  Vitamin C status may influence glycemic control. Investigators should be cognizant of the interaction of vitamins C and D and should take this into consideration in planning future studies.
authors.affiliation: University of Connecticut, Center on Aging, Farmington, Connecticut 06030-6232, USA. kositsawat@uchc.edu
authors.forename: Jatupol
authors.initials: J
authors.lastname: Kositsawat
authors.forename: Vincent L
authors.initials: VL
authors.lastname: Freeman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001205:Ascorbic Acid / Q000032:analysis / Q000378:metabolism*; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000517:prevention & control; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D016014:Linear Models; D008297:Male; D017058:Mexican Americans / Q000706:statistics & numerical data; D008875:Middle Aged; D015999:Multivariate Analysis; D009749:Nutrition Surveys; D014807:Vitamin D / Q000032:analysis / Q000378:metabolism; D055815:Young Adult
chemical_list: D001205:Ascorbic Acid; D001786:Blood Glucose; D006442:Glycated Hemoglobin; D014807:Vitamin D