Why it works:

The caffeine in coffee administered as an enema detoxifies the liver. While the coffee enema is being retained in the gut (for an optimum period ranging from 12 -15 minutes), all of the body's blood passes through the liver every three minutes. The hemorrhoidal blood vessels dilate from exposure to the caffeine, in turn, the liver's portal veins dilate too. Simultaneously, the bile ducts expand with blood, the bile flow increases, and the smooth muscles of these internal organs relax. The blood serum  and its many components are detoxified as this vital fluid passes through the individual's caffeinated liver. The quart of water being retained in the bowel stimulates the visceral nervous system, promoting peristalsis. The water delivered through the bowel dilutes the bile and causes an even greater increase in bile flow. There is a flushing of toxic bile which is further affected by the body's enzymatic catalyst known to physiologists as glutathion S-transferase (GST).

The GST is increased in quantity in the small bowel by 700 percent, which is an excellent physiological effect, because this enzyme quenches free radicals. These quenched radicals leave the liver and gallbladder as bile salts flowing through the duodenum. The bile salts are carried away by peristalsis in the gut, traveling from the small intestine, through the colon, an out the rectum.

The benefits of increasing quantities of GST in the gut:

GST binds bilirubin and its glucuronides so that they can be eliminated from the liver cells.

GST blocks and detoxifies carcinogens, which require oxidation or reduction to be activated. Its catalytic function produces a protective effect against many chemical carcinogens.

GST forms a covalent bond with nearly all free radical substances which is the precondition for their elimination from the body. The intermediate products of potential liver poisons also belong to this category of forming free radical pathology.

From The Gerson Therapy by Charlotte Gerson and Morton Walker