Problem
In general, it is claimed that only water and some salts are absorbed in the large gut, whereas the small gut is practically free of bacteria (which are present only in the large gut). In a patient on broad-spectrum antibiotics, bleeding can occur as a result of vitamin K deficiency. If the flora synthesizing vitamin K is disturbed, how can vitamin deficiency occur when the large gut is not supposed to absorb? How can this be due to a change in bacterial flora?