title: Relation of serum ascorbic acid to Helicobacter pylori serology in US adults: the Third National Health and Nutrition Examination Survey.
abstract: OBJECTIVE
  To examine the relation between serum ascorbic acid and Helicobacter pylori serology from a probability sample of US adults.
  
  
  METHODS
  Data from 6,746 adults (ages 20 to 90 years) enrolled in the Third National Health and Nutrition Examination Survey (NHANES III), 1988-1994 were analyzed. Multiple logistic regression models were examined taking into account sample weights and the complex survey design of NHANES III, and controlling for the effects of potential confounders. Because race appeared to modify the association between serum ascorbic acid and seropositivity to H. pylori, we conducted the analyses stratified by race.
  
  
  RESULTS
  A total of 2,189 adults (32%) had a positive serology for H. pylori, and, of these, 1,175 (54%) were positive for the CagA antigen. Among whites, a 0.50 mg/dL increase in serum ascorbic acid level was associated with decreased seroprevalence of H. pylori (Odds Ratio (OR) = 0.89, 95% confidence interval (CI) CI 0.82-0.96, p < 0.01). In analyses that controlled for seroprevalence of H. pylori, a 0.50 mg/dL increase in serum ascorbic acid level among whites was independently associated with a decreased seroprevalence of the pathogenic cagA-positive strain of H. pylori (OR = 0.31, 95% CI 0.12-0.79, p < 0.05). Serum ascorbic acid levels were not significantly associated with H. pylori serology among non-whites (all p > 0.05).
  
  
  CONCLUSIONS
  Higher serum levels of ascorbic acid were associated with a decreased seroprevalence of H. pylori and of the pathogenic cagA-positive strain of H. pylori among whites. If these associations are related causally and are not the result of residual confounding by factors such as socioeconomic status, ascorbic acid may affect the risk of H. pylori infection and in turn, the risk for peptic ulcer disease and gastric cancer among white Americans.
authors.affiliation: General Internal Medicine Section (111A1), Medical Service, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, CA 94121, USA. jasimon@itsa.ucsf.edu
authors.forename: Joel A
authors.initials: JA
authors.lastname: Simon
authors.forename: Esther S
authors.initials: ES
authors.lastname: Hudes
authors.forename: Guillermo I
authors.initials: GI
authors.lastname: Perez-Perez
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000097:blood*; D001426:Bacterial Proteins / Q000276:immunology; D005260:Female; D016481:Helicobacter Infections / Q000097:blood / Q000453:epidemiology* / Q000276:immunology; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D016017:Odds Ratio; D016036:Seroepidemiologic Studies; D014481:United States / Q000453:epidemiology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D000975:Antioxidants; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori; D001205:Ascorbic Acid