Original article Cola drinks consumption and oesophagitis* S. KapiciogÏlu 1 , A. Baki 1 , A. Reis 2 , Y. TekeliogÏlu 3 Karadeniz Technical University, School of Medicine, Department of Internal Medicine, 1 Section of Gastroenterology, Departments of 2 Pathology and 3 Histology, Trabzon Turkey 1 SUMMARY: For oesophageal epithelial changes to develop from gastro-oesophageal re¯ux disease (GORD), the character of the re¯uxate must be acid enough to cause injury. Experimentally, copious perfusion of the oesophagus with weak acid is quite harmless. However, hydrochloric acid alone with a pH below 3.0 may cause oesophageal injury. Cola drinks are strongly acidic (pH 2.5). This study analyses the in¯uence of and possible interaction between cola consumption and oesophagitis. Twenty rats were divided into two groups of 10. The animals received saline (pH 7.0) or cola (pH 2.6) per OS with 24 h free access to these solutions. After the experiment the oesophagus was dissected. The mucosa was macroscopically and histopathologically examined, and ¯ow cytometric analysis was used to look for proliferative activity. The histopathological analysis showed that there is no dierence between saline and cola. But the ®ndings of cell cycle analysis showed that the eects of cola and saline in inducing oesophageal mucosal damage are dierent. In the cola group the values were G 0 /G 1 , 7.33  2.88; S, 29.88  2.88; G 2 /M, 0.10  0.01; PI (proliferative±regenerative index), 29.76  2.88. The rat cell population g 0 /g 1 phases were found to be low (p < 0.01), and the cell population S and PI phases were found to be signi®cantly elevated compared with the control group (p < 0.01). (G 0 /G 1 , 79.30  5.97; S, 16.06  8.27; G 2 / M, 4.66  4.03; PI, 20.03  6.01). These results were re¯ected in the proliferative index, which is used as a measure of the regeneration index. The data show that cola has proliferative and regenerative eects on the oesophageal mucosa, and it is possible that its regenerative eect is caused as a result of an irritant eect. INTRODUCTION Oral regurgitation, the involuntary return of stomach acid to the mouth, is a common symptom of gastro- oesophageal re¯ux disease (GORD) and can cause acid erosion of the teeth and of the laryngitis. 1±3 Persistent oral regurgitation will damage the gingiva to an extent that seriously aects its appearance and function. For oesophageal epithelial changes or com- plications of GORD to develop, the character of the re¯uxate must be acid enough to cause injury. Experimentally, copious perfusion of the oesophagus with saline solution or weak acid is quite harmless, although hydrochloric acid alone with a pH below 3.0 may cause oesophageal injury. 4 Normally, the oeso- phageal pH returns to a value higher than 4.0 in about 15 swallows or fewer. An abnormal acid clearance time or an increased number of swallows for acid clearance is encountered in a substantial percentage of patients with re¯ux disease. 5 Cola, containing phos- phoric acid, has been shown to have erosive eects. 6,7 Experimental studies have shown that beverages containing citric acid cause the lowest pH values on the dorsal surface of the tongue; 8 however, in another study bovine teeth were immersed for up to 4 h in drinks containing phosphoric acid, and these drinks caused the deepest erosive lesions. 9 Thus, there is no doubt that the chemical composition of an acidic drink is important with regard to oesophagitis. Coca-Cola was chosen as a physiological exoge- nous acid consumed by millions of people every day. Cola drinks are strongly acid (pH 2.5). Oesophagitis may be caused by dietary acids. Therefore, this study analyses the interaction of consumption of cola drinks and oesophageal mucosal damage. MATERIALS AND METHODS Male Sprague±Dawley rats, weighing 200±300 g, were used for all experiments. The animals were left Address correspondence to: Professor Dr S. KapiciogÏ lu, Karadeniz Technical University School of Medicine, Department of Internal Medicine, Section of Gastroenterology, 61080 Trabzon, Turkey. Tel: (+90) 462 325 3011; Fax: (+90) 462 325 2270. *Presented at the VIIth World Congress, International Society for Diseases of the Esophagus, Montreal, 1±4 September 1998. 306 Diseases of the Esophagus (1999) 12, 306±308 Ó 1999 ISDE/Blackwell Science Asia