Normal values of 24-h ambulatory intraluminal impedance combined with pH-metry in subjects eating a Mediterranean diet

Background and aims: Multichannel intraluminal impedance combined with pH-metry is a novel technique for studying gastro-oesophageal reflux. As refluxes are particularly frequent after meals, we carried out this study in order to assess the impact of a Mediterranean diet on normal values of impedancemetry. Methods: Twenty-five Italian healthy subjects (13 men, median age 29 years, range 22-67 years) without reflux symptoms were recruited for this study. They underwent oesophageal 24-h impedance + pH-metry. A Mediterranean diet was given to all subjects on the day of examination and its total energy intake was 9668.5 kJ (2300 kcal). Results: A total of 1518 refluxes were recorded during 24 h with more upright than recumbent episodes (median 15 versus 0; p <0.01). The median total acid exposure time was 0.5% (range 0-4.2%). Acid and weakly acidic refluxes were equally reported (49% versus 51%). Weakly acidic episodes were more frequent than acid ones during 1-h postprandial periods (68% versus 32%; p <0.0001). Liquid-only and mixed refluxes reached the proximal oesophagus (15 cm above lower oesophageal sphincter) in 42.6% of cases. Median acid clearing time was longer than median bolus clearing time (28 s versus 12 s; p <0.01). Conclusions: This study provides normal values of pH-impedancemetry in Italian people eating a Mediterranean diet and are suitable for comparative pathophysiological investigations on reflux patients who have dietary habits similar to those of our country.