Feces

Feces are solid or semi-solid waste produced by the digestive system of animals, including humans. They consist of undigested food material, water, bacteria, and cells shed from the intestinal lining. They are expelled through the anus in a process known as defecation.

The color, shape, and consistency of feces are determined by the type of food consumed, the amount of water retained by the body, and overall health status. Persistent changes in these characteristics are commonly used by medical practitioners as indicators of digestive health or disease.

Formation

Food that is consumed passes through the stomach and small intestine, where most nutrients and water are absorbed. The remaining material enters the large intestine (colon), where additional water is absorbed and bacteria partly ferment the contents. The result is a solid substance stored in the rectum until defecation.

Composition

Water makes up the largest portion of feces. The remainder consists of living and dead bacteria, undigested fiber, fat, protein, and minerals. The brown color comes from the breakdown of bilirubin, a substance derived from the breakdown of red blood cells processed by the liver.

Health and disease transmission

Human feces can carry many disease-causing pathogens, including cholera, typhoid, and various parasites. When contaminated water is drunk or food is contaminated with feces, it causes serious infectious diseases, particularly in children. For this reason, sanitation of latrines, proper water treatment, and hand washing are among the most important measures for public health.

Uses

Animal feces have long been used as manure in agriculture. In many rural areas, dried manure has been used as a cooking fuel. It can also produce biogas from anaerobic decomposition. The use of human feces in agriculture requires prior treatment to reduce pathogenic organisms.