title: Vitamin C depletion is associated with alterations in blood histamine and plasma free carnitine in adults.
abstract: OBJECTIVE
  The purpose of this study was to determine whether carnitine metabolism or histamine degradation would be useful parameters for investigating the optimal requirement for vitamin C.
  
  
  METHODS
  Twenty-two non-scorbutic subjects with subnormal vitamin C status (plasma vitamin C < 28 mumol/L) were placed on a metabolic diet low in vitamin C for 3 weeks and repleted with graded doses of vitamin C: 10, 30 and 60 mg vitamin C daily (group 1) or 10,125 and 250 mg vitamin C daily (group 2) for weeks 1, 2 and 3, respectively. Fasting blood samples were collected weekly and analyzed for plasma vitamin C, plasma free carnitine and blood histamine.
  
  
  RESULTS
  Group 1 subjects remained in a subnormal vitamin C state throughout the 3-week study, and blood histamine and plasma free carnitine were not impacted by the experimental treatment. Plasma vitamin C in group 2 subjects rose significantly during the study, and these subjects finished the study with an ample vitamin C status indicative of vitamin C intakes above the recommended dietary allowance. Both blood histamine and plasma free carnitine were inversely related to vitamin C status in group 2 subjects.
  
  
  CONCLUSIONS
  These data indicate that blood histamine and plasma free carnitine are altered in individuals with subnormal, non-scorbutic vitamin C status and provide evidence that metabolic changes independent of collagen metabolism occur prior to the manifestation of scurvy. Thus utilizing scurvy as an end-point to determine vitamin C requirements may not provide adequate vitamin C to promote optimal health and well-being.
authors.affiliation: Department of Family Resources and Human Development, Arizona State University, Tempe 85287-2502, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Johnston
authors.forename: R E
authors.initials: RE
authors.lastname: Solomon
authors.forename: C
authors.initials: C
authors.lastname: Corte
mesh_terms: D000328:Adult; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000097:blood / Q000652:urine; D001206:Ascorbic Acid Deficiency / Q000097:blood* / Q000652:urine; D002331:Carnitine / Q000097:blood; D005260:Female; D006632:Histamine / Q000097:blood*; D006801:Humans; D008297:Male; D012614:Scurvy / Q000097:blood
chemical_list: D006632:Histamine; D001205:Ascorbic Acid; D002331:Carnitine