title: Folate synthesized by bacteria in the human upper small intestine is assimilated by the host.
abstract: OBJECTIVE
  Some intestinal flora are known to synthesize folate. The aim of this study was to determine whether folate synthesized by small intestinal flora is assimilated by the human host.
  
  
  METHODS
  Subjects with atrophic gastritis and healthy volunteers were studied before and after omeprazole administration. A double-lumen perfusion tube was placed in the duodenum. 3H-labeled P-aminobenzoic acid, a precursor substrate for bacterial folate synthesis, was perfused. Downstream intestinal aspirates and a 48-hour urine collection were obtained.
  
  
  RESULTS
  Atrophic gastritis and omeprazole administration were associated with increases in duodenal pH and in small intestinal flora. Bacterially synthesized folates were isolated from the intestinal aspirates. Tritiated 5-methyltetrahydrofolate, a major metabolite of folate, was isolated from the urine of omeprazole-treated subjects in greater quantities than from drug-free subjects (P<0.01); the quantity of tritiated 5-methyltetrahydrofolate in the urine of the subjects with atrophic gastritis was similarly elevated.
  
  
  CONCLUSIONS
  (1) Mild bacterial overgrowth caused by atrophic gastritis and administration of omeprazole are associated with de novo folate synthesis in the lumen of the small intestine; (2) the human host absorbs and uses some of these folates; and (3) the contribution to folate nutriture from this source remains unclear.
authors.affiliation: University Hospital de Santa Maria, Servico de Medicina 2, Lisbon, Portugal.
authors.forename: E
authors.initials: E
authors.lastname: Camilo
authors.forename: J
authors.initials: J
authors.lastname: Zimmerman
authors.forename: J B
authors.initials: JB
authors.lastname: Mason
authors.forename: B
authors.initials: B
authors.lastname: Golner
authors.forename: R
authors.initials: R
authors.lastname: Russell
authors.forename: J
authors.initials: J
authors.lastname: Selhub
authors.forename: I H
authors.initials: IH
authors.lastname: Rosenberg
mesh_terms: D010129:4-Aminobenzoic Acid / Q000378:metabolism; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000897:Anti-Ulcer Agents / Q000627:therapeutic use; D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D005492:Folic Acid / Q000096:biosynthesis / Q000378:metabolism*; D005757:Gastritis, Atrophic / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D007421:Intestine, Small / Q000378:metabolism / Q000382:microbiology*; D008297:Male; D009853:Omeprazole / Q000627:therapeutic use; D013763:Tetrahydrofolates / Q000652:urine
chemical_list: D000897:Anti-Ulcer Agents; D013763:Tetrahydrofolates; D005492:Folic Acid; D009853:Omeprazole; D010129:4-Aminobenzoic Acid; C005984:5-methyltetrahydrofolate