Ingesting one’s own feces, known scientifically as coprophagia, raises serious questions about potential biological consequences. This behavior involves significant risks related to infectious disease and gastrointestinal physiology. Understanding the composition of this waste material is the first step in assessing the health hazards it presents. This article details the makeup of feces, the specific illnesses that can result, and the body’s defense mechanisms against this threat.
What Feces Is Made Of
Human feces is composed primarily of water, accounting for approximately 75% of its total mass. The remaining 25% is solid material, a complex mixture of substances the body could not digest or absorb. A significant portion of this solid matter, between 25% and 54% of the dry weight, consists of bacterial biomass. These bacteria, though helpful in the gut, pose a high risk of causing infection upon re-ingestion because they are outside their intended environment.
The solid components also include undigested food matter, such as plant fibers and cellulose, which the human digestive system cannot break down. Feces also contains dead cells sloughed from the intestinal lining, small amounts of fat, protein, and inorganic substances like phosphate salts. This high concentration of viable and dead microorganisms, along with cellular debris, transforms the waste product into a source of potential danger.
The Primary Health Risks
The primary danger of ingesting feces lies in the fecal-oral route of transmission, where excreted pathogens are reintroduced into the digestive tract. Feces can harbor a vast array of infectious agents, including bacteria, viruses, and parasites, all capable of causing severe gastrointestinal illness. Pathogenic bacteria are a major concern, including harmful strains of Escherichia coli (such as O157:H7), Salmonella, Shigella, and Campylobacter. These bacteria are responsible for acute gastroenteritis, often leading to severe diarrhea, abdominal cramping, and fever.
Viruses shed in the stool can also lead to illness, even in small doses. Norovirus and Rotavirus are highly contagious causes of vomiting and diarrhea. Hepatitis A, another virus found in human waste, can cause liver inflammation and is dangerous because it survives outside the body for extended periods. Re-ingesting these pathogens completes their life cycle, allowing them to re-establish an infection.
Parasites represent another significant health risk, as many of their hardy, infective forms are excreted in the feces. Common organisms include Giardia intestinalis, Cryptosporidium, and Entamoeba histolytica. Cryptosporidium is protected by a resistant outer shell that allows it to survive harsh conditions and causes prolonged, watery diarrhea. Ingesting these pathogens can lead to new or repeat infections, with symptoms ranging from mild discomfort to life-threatening disease.
How the Digestive System Reacts
The body’s digestive system possesses multiple defensive layers designed to counteract the threat of ingested pathogens, starting with the stomach. The highly acidic environment of the stomach, where the gastric juice maintains a pH typically between 1.0 and 3.0, acts as a first-line chemical barrier. This low pH is designed to be instantly lethal to most microorganisms that enter the digestive tract.
If pathogens survive the acidic conditions, the body initiates a rapid physiological response to prevent intestinal colonization. Nausea and vomiting are immediate, forceful reactions intended to physically expel the toxic material. This reflex attempts to limit the infectious dose that reaches the small intestine.
The subsequent line of defense involves a massive inflammatory response in the gut lining, manifesting as severe diarrhea. Diarrhea is the body flushing itself out, utilizing increased water secretion and muscle contractions to rapidly move infectious agents out. While uncomfortable, this mechanism is a crucial survival tool. If pathogens bypass these defenses and penetrate the intestinal wall, there is a risk of systemic infection, spreading through the bloodstream to other organs.