title: The effects of a weakly acidic meal on gastric buffering and postprandial gastro-oesophageal reflux.
abstract: BACKGROUND
  Exclusion of the meal during ambulatory pH monitoring presumes that a meal completely buffers gastric acid and reflux of acidic food content cannot be distinguished from gastric acid. However, the ability of a meal to completely buffer gastric acid remains unclear.
  
  
  OBJECTIVE
  To determine the effect of a weakly acid meal on gastric buffering and oesophageal acid exposure.
  
  
  METHODS
  Patients undergoing multichannel intraluminal impedance pH studies were given a standard weakly acidic meal (pH = 5.9). Gastric and oesophageal pH was measured during the meal and in 15 min intervals for 2 h postprandially.
  
  
  RESULTS
  The study included 30 patients, with pathological acid reflux detected in 18 patients. Complete gastric buffering occurred in seven patients (23%) and was lost in all patients within 75 min of the meal. Oesophageal acid was detected in 33% of patients within 30 min of the meal and 81% of patients during the 2 h postprandial period. Postprandial oesophageal acid exposure was greater in patients with pathological acid reflux (9 ± 2.7% vs. 1.7 ± 0.8% P = 0.05) with a trend towards more incomplete gastric acid buffering and significant differences when measuring weak acid reflux (pH 4-5). Acid reflux rarely occurred in the absence of gastric acid, with gastric acid present in 74 of 79 (94%) fifteen minute postprandial intervals with acid reflux.
  
  
  CONCLUSIONS
  The ability of a meal to buffer gastric acid is poor. Early postprandial oesophageal acid reflux occurs in a substantial proportion of patients. Addition of a weakly acidic or pH neutral meal to ambulatory pH monitoring may unmask early postprandial acid reflux and provide data on gastric acid buffering.
authors: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester MN 55905, USA.
authors: K
authors: K
authors: Ravi
authors: D L
authors: DL
authors: Francis
authors: J A
authors: JA
authors: See
authors: D M
authors: DM
authors: Geno
authors: D A
authors: DA
authors: Katzka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002021:Buffers; D004032:Diet; D004435:Eating / Q000502:physiology; D005260:Female; D005502:Food; D005744:Gastric Acid / Q000378:metabolism*; D005745:Gastric Acidity Determination; D005764:Gastroesophageal Reflux / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period / Q000502:physiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D002021:Buffers