Relationships between diseases and their etiological significance.

All the results of a common cause will be related to one another. Consequently observed inter-relationships between diseases suggest some common causative factors. Certain characteristically western diseases have been shown to be related to one another in a number of different ways, including their order of emergence. This order with increasing age in western countries is the same as that of their emergence with the passage of time following the impact of western culture in developing countries. These observations are consistent with the hypothesis that they share some causative factor, and the removal of fiber from plant foods has been postulated to be such a factor.