The health of the colon and the skin are indicators of a person's internal health. They are essential aspects of the body's elimination system. A poorly functioning colon will produce a poor immune reaction and a lack of mental clarity. Skin conditions are much more a condition of internal health. If you cannot sweat well, you are not healthy nor will you be. You need to be able to have waste pass restricted through your body without having the associated toxins accumulate in your tissues. The cells also need to eliminate waste through efficient metabolism.
We are dependent upon healthy bacteria in our gut for many necessary functions of the brain and immune systems, but we have encouraged the growth of unhealthy bacterial and microbial activity. This is the basis behind all aging and the close association with chronic diseases.