The evidence indicating whether chocolate causes loose bowel movements is inconclusive. Some of the research reveals the caffeine in chocolate can cause loose stools, states Beth W. Orenstein for Everyday Health. Alternatively, other evidence indicates dark chocolate may inhibit loose stools, claims WebMD.
Caffeine is found in chocolate and stimulates the digestive system. It causes food to move through the digestive tract more quickly, which can result in diarrhea, explains Orenstein. Even so, in 2005, a study revealed that flavonoids contained in cocoa beans and dark chocolate products may help relieve diarrhea, according to WebMD. The flavonoids appear to inhibit intestinal fluid loss, which contributes to loose stools.