Effect of cigarette smoking on gastric emptying of solids in Japanese smokers: a crossover study using the 13C-octanoic acid breath test
Cigarette smoking is associated with an increased risk of peptic ulcer and gastroesophageal reflux disease. Gastric emptying disorders may play a role in the development of these upper gastrointestinal diseases. Thus, studies examining a link between smoking and gastric emptying disorders have clinical relevance. This study was conducted to investigate the effect of smoking on gastric emptying of solids in Japanese smokers. The 13C-octanoic acid breath test was performed in eight male habitual smokers on two randomized occasions (either sham smoking or actively smoking). The time vs 13CO2 excretion rate curve was mathematically fitted to a conventional formula of y (t) = m*k*β*e−k*t*(1 − e−k*t)β−1, and the parameters of k and β were determined: under the crossover protocol, a larger (smaller) β indicates slower (faster) emptying in the early phase, and a larger (smaller) k indicates faster (slower) emptying in the later phase. The half 13CO2 excretion time (t1/2b = −[ln(1 − 2−1/β)]/k) and the time of maximal 13CO2 excretion rate (tmax = [lnβ]/k) were also calculated. Between the two occasions, k, β, t1/2b, and tmax were compared by the Wilcoxon signed-rank test. After smoking, k was significantly increased. No significant differences were found in β, t1/2, and tmax between the two occasions. The increase in k suggests the acceleration of gastric emptying in the later phase. For the first time, this study has revealed that acute smoking speeds the gastric emptying of solids in Japanese habitual smokers.