The perceived effect of various foods and beverages on stool consistency

Some people believe that chocolate and other foods or beverages may cause constipation. This study was undertaken to quantify the effect of potentially constipating foods and beverages on apparently healthy and constipated populations of German individuals.

A questionnaire asking for the effect of certain foods and beverages on stool form (perceived consistency) was answered by 200 healthy controls, 122 patients with chronic constipation, and 766 patients with irritable bowel syndrome with constipation (IBS-C).

Patients with constipation or IBS-C reported altered stool form after food and beverage consumption more often than controls (controls 42.5% vs constipation 52.0% vs IBS-C 57.0%, P < 0.001). Controls experienced hardening of stools less often and experienced softening more often than either constipation or IBS-C patients. When patients were asked which foods or beverages caused constipation (open ended question), chocolate was most frequently mentioned, followed by white bread and bananas. The results of systematic questioning yielded chocolate (48-64% of respondents), bananas (29-48%), and black tea (14-24%) as constipating, while prunes (41-52%), coffee (14-24%), wine (8-30%), beer (14-24%), and smoking (42-70% in those who smoked) were considered stool softeners.

Several foodstuffs may exert an effect on stool consistency. Chocolate, bananas and black tea are perceived to cause constipation, while prunes are perceived to soften stools in many people. Coffee, wine and beer were perceived to soften stools in a minority of people. Cigarettes are perceived to soften stools by about half of the smokers.