title: Fecal phytate excretion varies with dietary phytate and age in women.
abstract: OBJECTIVE
  Information on the excretion of dietary phytate in humans under different conditions is limited. The purpose of this study was to investigate fecal excretion of dietary phytate and phosphorus in a group of young and elderly women consuming high and low phytate diets.
  
  
  METHODS
  Fifteen young and fourteen elderly women were fed two experimental diets, high phytate and low phytate, for 10 days each with a washout period of 10 days between the two diet periods. Duplicate diet samples from two different menus and complete fecal samples were collected for 5 days during each diet period and analyzed for phytate and phosphorus contents. Mean daily excretions and percentages of dietary intakes of phytate and phosphorus were calculated.
  
  
  RESULTS
  Dietary phytate level does impact phytate excretion, but the effect was observed only in young subjects. Fecal phytate excretion of young subjects during the high phytate diet (313 mg/d) was significantly higher than during the low phytate diet (176 mg/d), however, that of elderly subjects did not vary with dietary phytate levels. Phosphorus excretion, net absorption, and apparent absorption rate were affected by dietary phytate level but not by the age of the subjects.
  
  
  CONCLUSIONS
  Results of this study indicate that phytate degradation in the gastrointestinal tract is substantial and more variable in young women than in elderly women. The high capacity of phytate degradation in elderly subjects may be related to long-term phytate intake but needs further clarification. Both beneficial and adverse health effects of phytate need to be studied considering the long-term phytate intake and age of subjects as well as dietary phytate levels.
authors.affiliation: Graduate School of Public Health, Seoul National University, Seoul 151-742, Korea.
authors.forename: Hyojee
authors.initials: H
authors.lastname: Joung
authors.forename: Bo Y
authors.initials: BY
authors.lastname: Jeun
authors.forename: Shan J
authors.initials: SJ
authors.lastname: Li
authors.forename: Jihye
authors.initials: J
authors.lastname: Kim
authors.forename: Leslie R
authors.initials: LR
authors.lastname: Woodhouse
authors.forename: Janet C
authors.initials: JC
authors.lastname: King
authors.forename: Ross M
authors.initials: RM
authors.lastname: Welch
authors.forename: Hee Y
authors.initials: HY
authors.lastname: Paik
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000378:metabolism*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D008875:Middle Aged; D010758:Phosphorus / Q000032:analysis; D016226:Phosphorus, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics*; D010833:Phytic Acid / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D016226:Phosphorus, Dietary; D010758:Phosphorus; D010833:Phytic Acid