What do we know about the human digestive system not working for that long of a time?

There are many groups of medical patients, including preterm infants, coma patients, and cancer patients that undergo long periods of TPN use as their only source of nutrition. As a result, doctors have long had concerns over the effects of TPN and its long term affect on the human digestive system. Thirteen different studies have been conducted on over 400 infants and children between the ages approximately 4 months to 17 years old, and almost 100 healthy adults control subjects to identify complications such as gastrointestinal bacterial overgrowth and sepsis, impaired immune functions, overall mortality including bowel or stomach perforation, intestinal villous atrophy, and the effects of TPN on gut mobility. Based on this literature there is no evidence suggesting that TPN promotes bacterial overgrowth, impairs neutrophil functions, inhibits blood’s bactericidal effect, causes villous atrophy, or increases the risk of death due to gastrointestinal complications. The hypothesis of a negative effect of TPN, while commonly cited by many doctors, was also unproven in these studies.

The most common complication that can occur in adults from prolonged TPN use is a complication after returning to normal food called “refeeding syndrome”. “Refeeding syndrome” is a complication in patients that have gone without food for a long period time (usually greater than 5 days). When food is reintroduced to the patient they can have rapid disturbances in their electrolyte levels, causing complications with their body chemistry. This is a rare complication with TPN and can be easily prevented with the proper re-introduction of oral food and the proper monitoring and correction of the person’s electrolytes.