title: Total Duration of Breastfeeding, Vitamin D Supplementation, and Serum Levels of 25-Hydroxyvitamin D.
abstract: OBJECTIVE
  To determine the association between total breastfeeding duration and serum 25-hydroxyvitamin D (25-OHD) and to explore whether vitamin D supplementation influences this association.
  
  
  METHODS
  We conducted a cross-sectional study of healthy children between September 2011 and August 2013 through the TARGet Kids! primary health care research network. Of the 4533 eligible children, we included only the 2508 who had 25-OHD measured. We assessed adjusted associations of total breastfeeding duration (in months) with serum 25-OHD and in supplemented versus nonsupplemented children, with the odds of 25-OHD less than 20 nanograms per milliliter.
  
  
  RESULTS
  Each 1-month increase in total breastfeeding duration was associated with a 0.12 nanograms per milliliter lower median serum 25-OHD (95% confidence interval [CI] = -0.21 ng/mL, -0.02 ng/mL) among children who were not supplemented. The odds of serum 25-OHD less than 20 nanograms per milliliter increased by 6% (odds ratio [OR] = 1.06; 95% CI = 1.03, 1.10) for every 1-month increase in total breastfeeding duration among nonsupplemented children. The interaction between vitamin D supplementation, duration of breastfeeding, and median serum 25-OHD was statistically significant (P = .04).
  
  
  CONCLUSIONS
  Breastfed children who were not supplemented, particularly those breastfed more than 1 year, appear to have lower vitamin D status. Vitamin D supplementation may mitigate this risk. These findings support recommendations for supplementation during breastfeeding of any duration.
authors.affiliation: Denise Darmawikarta, Yang Chen, Gerald Lebovic, and Jonathan L. Maguire are with the Applied Health Research Centre, Li Ka Shing Knowledge Institute of St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Catherine S. Birken, Patricia C. Parkin, and Jonathon L. Maguire are with the Department of Pediatrics, Hospital for Sick Children, Toronto, and the Department of Pediatrics, University of Toronto.
authors.forename: Denise
authors.initials: D
authors.lastname: Darmawikarta
authors.affiliation: Denise Darmawikarta, Yang Chen, Gerald Lebovic, and Jonathan L. Maguire are with the Applied Health Research Centre, Li Ka Shing Knowledge Institute of St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Catherine S. Birken, Patricia C. Parkin, and Jonathon L. Maguire are with the Department of Pediatrics, Hospital for Sick Children, Toronto, and the Department of Pediatrics, University of Toronto.
authors.forename: Yang
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Denise Darmawikarta, Yang Chen, Gerald Lebovic, and Jonathan L. Maguire are with the Applied Health Research Centre, Li Ka Shing Knowledge Institute of St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Catherine S. Birken, Patricia C. Parkin, and Jonathon L. Maguire are with the Department of Pediatrics, Hospital for Sick Children, Toronto, and the Department of Pediatrics, University of Toronto.
authors.forename: Gerald
authors.initials: G
authors.lastname: Lebovic
authors.affiliation: Denise Darmawikarta, Yang Chen, Gerald Lebovic, and Jonathan L. Maguire are with the Applied Health Research Centre, Li Ka Shing Knowledge Institute of St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Catherine S. Birken, Patricia C. Parkin, and Jonathon L. Maguire are with the Department of Pediatrics, Hospital for Sick Children, Toronto, and the Department of Pediatrics, University of Toronto.
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Birken
authors.affiliation: Denise Darmawikarta, Yang Chen, Gerald Lebovic, and Jonathan L. Maguire are with the Applied Health Research Centre, Li Ka Shing Knowledge Institute of St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Catherine S. Birken, Patricia C. Parkin, and Jonathon L. Maguire are with the Department of Pediatrics, Hospital for Sick Children, Toronto, and the Department of Pediatrics, University of Toronto.
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Parkin
authors.affiliation: Denise Darmawikarta, Yang Chen, Gerald Lebovic, and Jonathan L. Maguire are with the Applied Health Research Centre, Li Ka Shing Knowledge Institute of St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Catherine S. Birken, Patricia C. Parkin, and Jonathon L. Maguire are with the Department of Pediatrics, Hospital for Sick Children, Toronto, and the Department of Pediatrics, University of Toronto.
authors.forename: Jonathon L
authors.initials: JL
authors.lastname: Maguire
mesh_terms: D001942:Breast Feeding; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D013997:Time Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000097:blood / Q000517:prevention & control
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D