The level of indican is an index of the efficiency of protein digestion. Compromised amino acid or protein digestion can be caused by insufficient gastric hydrochloric acid, insufficient digestive enzymes, adverse food reactions, parasitic infection, fungal infection, an overgrowth of bacteria that metabolize specific proteins, hypermotility of the small intestine, or other gastrointestinal dysfunction.
Putrefaction is especially important because it can produce dozens of types of carcinogens. These substances can enter the liver through the general circulation. Undigested protein also increases systemic toxicity, burdening the detoxification capacity of the liver. Poor protein digestion can lead to other problems, such as intestinal microbial overgrowth, which in turn can lead to unfavorable pH changes and impaired absorption.