What is the process of taking food in the body called?

January 5, 2026 •

2 min read

Over 90% of a food's nutrients are absorbed in the small intestine, but this complex journey begins with a single, crucial step. That first action—taking food into the body—is known as ingestion, and it is the starting point of the entire digestive process.

Quick Summary

Ingestion is the initial act of taking food into the mouth, which kicks off the multi-stage digestive process. This biological function precedes the mechanical and chemical breakdown of food, the absorption of nutrients, and the final elimination of waste.

Key Points

Ingestion is the first step: The process of taking food into the body is called ingestion, and it occurs in the mouth.
Four main stages: Food processing involves four main stages: ingestion, digestion, absorption, and elimination.
Digestion begins in the mouth: Chewing and saliva begin the mechanical and chemical breakdown of food immediately upon ingestion.
The small intestine is key for absorption: Most nutrient absorption takes place in the small intestine due to its large surface area.
Waste is eliminated last: After nutrients and water have been absorbed, the remaining undigested waste is expelled from the body through elimination.

The First Step: Ingestion and the Oral Cavity

The digestive process involves several stages, beginning with ingestion, the act of consuming food or liquid by taking it into the mouth. This initial step involves mechanical breakdown through chewing (mastication), increasing the food's surface area for enzymes. Saliva mixes with the food, containing enzymes like salivary amylase that start carbohydrate digestion, and mucus that lubricates the food, forming a swallowable bolus.

The Digestive Journey Continues

Following ingestion, food moves through the digestive tract via propulsion, including peristalsis.

The Stomach: Churning and Acidic Breakdown

In the stomach, the bolus mixes with acidic gastric juices and enzymes like pepsin, breaking down proteins. This forms chyme, a semi-liquid mixture released into the small intestine.

The Small Intestine: Absorption is Key

The small intestine is where most digestion and absorption occur. Chyme mixes with pancreatic enzymes and bile. Villi, tiny projections on the intestinal walls, increase the surface area for efficient absorption of nutrients into the bloodstream or lymphatic system.

The Large Intestine: Water and Waste

Undigested material moves to the large intestine, primarily for water absorption and forming solid waste (stool). Gut bacteria also help break down remaining food particles.

Comparison of Digestive Stages


Digestive Stage	Primary Location	Key Function	Example Action
Ingestion	Mouth	Taking food into the body	Chewing and swallowing food
Digestion	Mouth, Stomach, Small Intestine	Mechanically and chemically breaking down food	Stomach churning and enzyme secretion
Absorption	Small and Large Intestine	Absorbing nutrients and water into the bloodstream	Nutrients moving through villi into capillaries
Elimination	Large Intestine, Rectum, Anus	Expelling undigested waste from the body	Defecation

The Final Stage: Elimination

Elimination (egestion or defecation) is the removal of indigestible waste from the body via the rectum and anus. Feces are stored in the rectum before expulsion.

Conclusion: A Symphony of Processes

Ingestion, the act of taking food into the body, is the starting point of a complex, coordinated digestive process. This journey involves distinct stages—ingestion, digestion, absorption, and elimination—each crucial for obtaining energy and nutrients. Understanding these phases illuminates the sophisticated mechanisms that power our bodies.

For additional detail on the various enzymes involved, the US National Library of Medicine provides comprehensive information on digestion physiology.

Key Factors Influencing Digestion

Mastication: Thorough chewing is vital for efficient digestion by increasing food surface area. Enzymatic Activity: Enzymes in saliva, gastric juices, and the small intestine are critical for chemical breakdown. Peristalsis: These involuntary muscle contractions move food through the digestive tract. Absorption Surface: Villi in the small intestine maximize nutrient absorption. Gut Microbiome: Bacteria in the large intestine aid in breaking down remaining food particles. Hormonal Regulation: Hormones control digestive juice secretion and digestion pace. Elimination of Waste: Expelling undigested material prevents waste buildup.

Frequently Asked Questions

Ingestion is the physical act of taking food into the mouth, which is the very first step. Digestion is the subsequent process of breaking down that ingested food into smaller, absorbable molecules.

Ingestion occurs in the mouth, where food is chewed and mixed with saliva before being swallowed.

The primary purpose of ingestion is to introduce food and other substances into the body's digestive system so that it can be processed for energy, growth, and cellular repair.

Immediately after ingestion, the process of chewing (mastication) begins, and salivary glands release saliva containing enzymes that start to break down starches.

If a substance is ingested but cannot be digested or absorbed, it will pass through the digestive tract and be eliminated from the body as waste, a process known as egestion.

Swallowing is part of the ingestion process. Ingestion encompasses the entire act of taking food into the mouth, chewing it, and then swallowing it to move it towards the stomach.

The tongue is essential during ingestion for manipulating the food inside the mouth, mixing it with saliva, and forming it into a bolus that is then pushed to the back of the throat for swallowing.