title: Inflammation and Vitamin A.
abstract: BACKGROUND
  Serum retinol concentrations are homeostatically controlled and only fall when liver stores of vitamin A are very low. Nevertheless, low concentrations of serum retinol occur in apparently healthy people where there is no evidence of vitamin A deficiency (VAD).
  
  
  OBJECTIVE
  To determine the reason for low serum vitamin A concentrations where there is no VAD.
  
  
  METHODS
  We observed that elevated acute-phase protein (APP) concentrations often accompanied low retinol concentrations, and we developed a model of the inflammatory response to categorize 4 groups of participants termed reference (no raised APP), incubation (raised acute APP only), early convalescence (both acute and chronic APP raised), and late convalescence (raised chronic APP only). We identified 7 studies with participants who could be allocated to the 4 groups, and using meta-analysis methods we calculated correction (ie, multiplication) factors 1.13, 1.24, and 1.11 to remove the influence of inflammation from the incubation, early, and late convalescent groups, respectively.
  
  
  CONCLUSIONS
  In nutrition surveys or intervention studies to measure vitamin A status, workers should measure APP and correct retinol concentrations using the multiplication factors where inflammation is found.
authors: Northern Ireland Centre for Food and Health, School of Biomedical Sciences, Coleraine, United Kingdom di.thurnham@ulster.ac.uk.
authors: David I
authors: DI
authors: Thurnham
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism*; D019317:Evidence-Based Medicine; D006306:Health Surveys / Q000706:statistics & numerical data*; D006801:Humans; D007249:Inflammation / Q000097:blood*; D014801:Vitamin A / Q000097:blood*; D014802:Vitamin A Deficiency / Q000097:blood / Q000453:epidemiology*
chemical_list: D000209:Acute-Phase Proteins; D014801:Vitamin A
keywords: health surveys; inflammation; micronutrient deficiency; vitamin A