title: Effect of supplementation with vitamin D₃ on glucose production pathways in human subjects.
abstract: METHODS
  Research reports suggest that vitamin D affects glucose and insulin metabolism; however, the exact mechanisms are unclear. ²H NMR analysis of monoacetone glucose (MAG) after tracer administration provides a non-invasive method of profiling hepatic glucose metabolism. This study examined the effects of supplementation with vitamin D₃ on contribution of glycogenolysis to glucose production.
  
  
  RESULTS
  Tracer administration and biofluid collections were performed with eight healthy females before and following a 4-wk vitamin D₃ administration period. Following an overnight fast subjects ingested deuterated water and acetaminophen. Full void urine samples were collected after 4 h. ²H NMR spectra of urinary monoacetone glucose were acquired to determine the contribution of glycogenolysis to glucose production. The mean contribution of glycogenolysis to glucose production was 60±13%. Supplementation with vitamin D₃ had no effect on hepatic glucose production. Regression analysis revealed a significant relationship between carbohydrate intake and the contribution of glycogenolysis (β=0.914, p=0.004).
  
  
  CONCLUSIONS
  In conclusion, we saw no changes in the percentage contribution of glycogenolysis following supplementation with vitamin D₃. The reproducibility of our results and the non-invasive nature of the method highlight the potential for this method in assessing mechanistic modes of action in future nutritional interventions.
authors.affiliation: UCD Institute of Food and Health, University College Dublin, Ireland.
authors.forename: Aifric
authors.initials: A
authors.lastname: O'Sullivan
authors.forename: Daniele
authors.initials: D
authors.lastname: Balducci
authors.forename: Francesca
authors.initials: F
authors.lastname: Paradisi
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Cashman
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gibney
authors.forename: Lorraine
authors.initials: L
authors.lastname: Brennan
mesh_terms: D000328:Adult; D002762:Cholecalciferol / Q000494:pharmacology*; D003903:Deuterium; D019587:Dietary Supplements; D005260:Female; D005947:Glucose / Q000031:analogs & derivatives / Q000032:analysis / Q000378:metabolism*; D050261:Glycogenolysis / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D011849:Radioactive Tracers; D012044:Regression Analysis
chemical_list: D011849:Radioactive Tracers; C028223:1,2-O-isopropylidene-D-glucofuranose; D002762:Cholecalciferol; D003903:Deuterium; D005947:Glucose