Introduction: The red dragon fruit (Hylocereus polyrhizus) is a popular fruit, not only where it originated from, in Central America, but across the world including in Asia. It contains healthy minerals, vitamins and antioxidants, and has been shown to have gut motility action in animals. Methods: To determine the effect of red dragon fruit on whole gut transit time, a cross-sectional study of whole gut transit time using two different stool markers was conducted among 128 young Malaysian adults. Results: Red dragon fruit, in a half fruit serving of 225±25 grams, reduced mean whole gut transit time from 26.0±12.9 hours to 21.9±12.8 hours (p<0.001) when colour change in stools was used as an indicator. The tests also showed that 14.8-17.3% of individuals had whole gut transit time ≥40 hours with carbon as a stool marker compared to only 7.8-8.6% when red dragon fruit was consumed and used as a marker. Conclusion: This study demonstrated a laxative effect of red dragon fruit among young adults.