Background: Coffee and tea are believed to cause gastro-oesophageal re
flux; however, the effects of these beverages and of their major compo
nent, caffeine, have not been quantified. The aim of this study was to
evaluate gastro-oesophageal reflux induced by coffee and tea before a
nd after a decaffeination process, and to compare it with water and wa
ter-containing caffeine. Methods: Three-hour ambulatory pH-metry was p
erformed on 16 healthy volunteers, who received 300 ml of (i) regular
coffee, decaffeinated coffee or tap water (n = 16), (ii) normal tea, d
ecaffeinated tea, tap water, or coffee adapted to normal tea in caffei
ne concentration (n = 6), and (iii) caffeine-free and caffeine-contain
ing water (n = 8) together with a standardized breakfast. Results: Reg
ular coffee induced a significant (P < 0.05) gastro-oesophageal reflux
compared with tap water and normal tea, which were not different from
each other. Decaffeination of coffee significantly (P < 0.05) diminis
hed gastro-oesophageal reflux, whereas decaffeination of tea or additi
on of caffeine to water had no effect. Coffee adapted to normal tea in
caffeine concentration significantly (P < 0.05) increased gastro-oeso
phageal reflux. Conclusions: Coffee, in contrast to tea, increases gas
tro-oesophageal reflux, an effect that is less pronounced after decaff
eination. Caffeine does not seem to be responsible for gastro-oesophag
eal reflux which must be attributed to other components of coffee.