title: Effect of trypsin and mucin on heme iron bioavailability in humans.
abstract: In the human gastrointestinal tract, trypsin and mucin may affect the absorption of heme iron. However, these interactions have not been well-established. We determined the effect of trypsin and mucin on heme iron absorption in humans.
  
  
  METHODS
  Twenty-eight apparently healthy females participated in two studies (14 per study). Study A evaluated the effect of trypsin on iron bioavailability. Subjects ingested 100 mg trypsin and 1.7 g mucin on 5 mg heme iron bioavailability on days 1, 2, 14, and 15, respectively. In study B, which assessed the effect of mucin on heme iron bioavailability, the subjects ingested hemin, hemin plus mucin, hemoglobin (Hb), and Hb plus mucin, on days 1, 2, 14, and 15, respectively.
  
  
  RESULTS
  In study A, the geometric means ± 1 SD of heme iron absorption were 5.1 % (3.1-8.3), 2.9 % (1.6-5.1), 7.3 % (4.1-13.1), and 6 % (2.7-13) for hemin, hemin plus trypsin, Hb plus trypsin, and Hb plus mucin plus trypsin, respectively. In study B, the geometric means ± 1 SD of heme iron absorption were 16.4 % (10.5-25.7), 13.1 % (9.0-18.9), 13.7 % (9.0-20.7), and 11.8 % (7.6-18.3) for hemin, hemin plus mucin, Hb, and Hb plus mucin, respectively. The ratio increased when Hb plus trypsin was ingested and decreased when hemin plus trypsin was ingested. There were no differences in other ratios with respect to the ratio on day 1 (P < 0.05).
  
  
  CONCLUSIONS
  Trypsin is the only human gastrointestinal protein that evaluated the affects of heme iron absorption. However, this effect depends on how heme iron is ingested.
authors.affiliation: Micronutrients Laboratory, Institute of Nutrition and Food Technology (INTA), University of Chile, Avda El Líbano 5524, Casilla 13811, Santiago, Chile.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Cediel
authors.forename: Manuel
authors.initials: M
authors.lastname: Olivares
authors.forename: Diego
authors.initials: D
authors.lastname: Gaitán
authors.forename: Sebastian
authors.initials: S
authors.lastname: Flores
authors.forename: Alex
authors.initials: A
authors.lastname: Brito
authors.forename: Fernando
authors.initials: F
authors.lastname: Pizarro
mesh_terms: D000328:Adult; D018798:Anemia, Iron-Deficiency / Q000178:diet therapy; D002677:Chile; D019587:Dietary Supplements / Q000009:adverse effects; D005260:Female; D006418:Heme / Q000378:metabolism*; D006427:Hemin / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007408:Intestinal Absorption; D007504:Iron Radioisotopes; D019266:Iron, Dietary / Q000378:metabolism*; D008875:Middle Aged; D009077:Mucins / Q000009:adverse effects / Q000378:metabolism* / Q000627:therapeutic use; D009753:Nutritive Value; D013608:Tablets, Enteric-Coated; D014357:Trypsin / Q000378:metabolism* / Q000627:therapeutic use
chemical_list: D006454:Hemoglobins; D007504:Iron Radioisotopes; D019266:Iron, Dietary; D009077:Mucins; D013608:Tablets, Enteric-Coated; D006418:Heme; D006427:Hemin; D014357:Trypsin