Coffee enemas are the enema-related procedure of inserting coffee into the anus to cleanse the rectum and large intestines. This procedure, although well documented, is considered by most medical authorities to be unproven, rash and potentially dangerous.
While the idea of rectal cleansing dates back to the Ancient Egyptians, the notion of caffeine as an enema-related substance is relatively new. It was conceived in 1917, and first appeared in the Merck Manual in 1972.
In 1920, German scientists investigated caffeine's effect on the bile duct and small intestines. Max Gerson proposed that coffee enemas had a positive effect on the gastro-intestinal tract. Gerson said that coffee enemas had positive effects on patients with tuberculosis, and later even those with cancer. He claimed that unlike saline enemas, the caffeine traveled through the smooth muscle of the small intestine, and into the liver. This, he said, cleared even more of the gastro-intestinal tract and removed more toxins and bile than a normal enema. He told his patients often that the "coffee enemas are not given for the function of the intestines but for the stimulation of the liver."
Effects and dangers 
Some proponents of alternative medicine have claimed that coffee enemas have an anti-cancer effect by "detoxifying" metabolic products of tumors. There is no medical scientific evidence to support any anti-cancer effect of coffee enemas.
Coffee enemas can cause numerous side effects, including infections, sepsis (including campylobacter sepsis), severe electrolyte imbalance, colitis, polymicrobial enteric septicemia, proctocolitis, salmonella, brain abscess, and heart failure. If the coffee is inserted too quickly or is too hot, it could cause internal burning or rectal perforation. Long term use of coffee enemas can lead to malabsorption of fat, fat-soluble vitamins, and calcium.
The use of coffee enemas has led to several deaths as a result of severe electrolyte imbalance, hyponatremia, dehydration, pleural and pericardial effusions. The U.S. Food and Drug Administration (FDA) has ruled that study participants must be warned of the risk of death from coffee enemas in studies that use them.
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