Britannica
Sources used in this answer
How do ingestion, digestion, and egestion differ in humans?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
human nutrition
MyPlate, a revised set of dietary guidelines introduced by the U.S. Department of Agriculture (USDA) in 2011, divides the four basic food groups (fruits, grains, protein, and vegetables) into sections on a plate, the size of each section representing the relative dietary proportions of each food group. The small blue circle shown at the upper right illustrates the inclusion and recommended proportion of dairy products in the diet.
In human physiology, ingestion, digestion, and egestion represent distinct stages of the process by which the body acquires and utilizes nutrients.1
- Ingestion: This is the initial act of taking food and liquids into the body through the mouth. It involves chewing and mixing food with saliva to form a bolus, which is then swallowed.23
- Digestion: This is the sequence of physical and chemical changes that break down food into forms the body can use. It begins in the mouth and continues in the stomach, where gastric juices turn food into a semiliquid substance called chyme. In the small intestine, further enzymatic action breaks down particles so that nutrients can be absorbed into the bloodstream.143
- Egestion: This is the final stage, involving the elimination of indigestible waste. After the small intestine absorbs nutrients, the remaining material moves to the large intestine, where water and salts are reabsorbed. The large intestine compacts this waste—which includes undigested matter, bacteria, and cast-off cells—into feces, which are then expelled from the body through the anus.153