title: Serum vitamin C and the prevalence of vitamin C deficiency in the United States: 2003-2004 National Health and Nutrition Examination Survey (NHANES).
abstract: BACKGROUND
  Vitamin C (ascorbic acid) may be the most important water-soluble antioxidant in human plasma. In the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994), approximately 13% of the US population was vitamin C deficient (serum concentrations <11.4 micromol/L).
  
  
  OBJECTIVE
  The aim was to determine the most current distribution of serum vitamin C concentrations in the United States and the prevalence of deficiency in selected subgroups.
  
  
  METHODS
  Serum concentrations of total vitamin C were measured in 7277 noninstitutionalized civilians aged > or =6 y during the cross-sectional, nationally representative NHANES 2003-2004. The prevalence of deficiency was compared with results from NHANES III.
  
  
  RESULTS
  The overall age-adjusted mean from the square-root transformed (SM) concentration was 51.4 micromol/L (95% CI: 48.4, 54.6). The highest concentrations were found in children and older persons. Within each race-ethnic group, women had higher concentrations than did men (P < 0.05). Mean concentrations of adult smokers were one-third lower than those of nonsmokers (SM: 35.2 compared with 50.7 micromol/L and 38.6 compared with 58.0 micromol/L in men and women, respectively). The overall prevalence (+/-SE) of age-adjusted vitamin C deficiency was 7.1 +/- 0.9%. Mean vitamin C concentrations increased (P < 0.05) and the prevalence of vitamin C deficiency decreased (P < 0.01) with increasing socioeconomic status. Recent vitamin C supplement use or adequate dietary intake decreased the risk of vitamin C deficiency (P < 0.05).
  
  
  CONCLUSIONS
  In NHANES 2003-2004, vitamin C status improved, and the prevalence of vitamin C deficiency was significantly lower than that during NHANES III, but smokers and low-income persons were among those at increased risk of deficiency.
authors.affiliation: Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA. rschleicher@cdc.gov
authors.forename: Rosemary L
authors.initials: RL
authors.lastname: Schleicher
authors.forename: Margaret D
authors.initials: MD
authors.lastname: Carroll
authors.forename: Earl S
authors.initials: ES
authors.lastname: Ford
authors.forename: David A
authors.initials: DA
authors.lastname: Lacher
mesh_terms: D000293:Adolescent; D000328:Adult; D001205:Ascorbic Acid / Q000097:blood*; D001206:Ascorbic Acid Deficiency / Q000453:epidemiology*; D015992:Body Mass Index; D002648:Child; D003430:Cross-Sectional Studies; D004032:Diet; D019587:Dietary Supplements; D005006:Ethnicity / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D009749:Nutrition Surveys; D011203:Poverty / Q000706:statistics & numerical data; D011336:Probability; D012907:Smoking / Q000009:adverse effects; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D001205:Ascorbic Acid