In a crossover study, volunteers consumed a diet supplemented with either wheat or rye bread. Levels of faecal mucus were determined and the adhesion of five selected probiotics to immobilized intestinal mucus, was assessed. No significant difference in the concentration of faecal mucus or adhesion of the probiotics to the mucus was observed during the two dietary periods. However, male subjects were observed to excrete significantly more mucus during the rye bread supplemented diet. From these observations it was concluded that these two diets, with a low or high fibre content, did not change the potential binding sites for the tested probiotics or affect the level of mucus excreted in the faeces, however, on a high fibre diet men excrete more faecal mucus.