In Reply.—Dr Graham's interest in and comments on our work are appreciated. As our attention focuses increasingly on diet and other environmental factors that affect disease states, we agree that we must exert great care attributing these relationships to cause and effect. This is particularly important in an era when nutritional data evolve into national policy.
Abnormal bowel movements have been characterized as disease states since the second century ad, when Arataeus described diarrhea as "the discharge of undigested food in a fluid state." Attempts to quantify diarrhea more precisely have met with little success, since "normal" bowel function differs for each person. Even the best index, stool weight, cannot suffice, particularly in cross-cultural comparisons.1 Thus, one cannot use these measures alone to standardize what is diarrhea and what is not. One must evaluate the change in stool pattern for the individual patient.
The patients described in