How Digestion Works
Quick answer
Digestion breaks food into smaller components that can be absorbed and used. Mechanical movement, enzymes, acid, bile, microbes and the intestinal lining all contribute.
Mouth and stomach
Chewing increases surface area. Saliva begins digestion, while the stomach mixes food with acid and enzymes.
Small intestine
Most nutrient digestion and absorption occur here. Pancreatic enzymes and bile help process carbohydrate, protein and fat.
Large intestine
Water and electrolytes are absorbed, and microbes ferment some fibres, producing compounds that interact with the intestinal environment.
A sandwich is not absorbed as “sandwich.” Starch is broken toward simple sugars, protein toward amino acids and fat toward fatty acids and related molecules.
Key terms
| Digestion | Mechanical and chemical breakdown of food. |
|---|---|
| Absorption | Movement of nutrients into blood or lymph. |
| Enzyme | A protein that speeds a chemical reaction. |
| Microbiome | The community of microbes living in a particular environment. |
Common mistakes
- Thinking digestion happens only in the stomach. It begins in the mouth and continues through the digestive tract.
- Assuming every digestive symptom is caused by one specific food.
- Using “detox” products to do work the digestive system, liver and kidneys already perform.
Practical takeaway
Digestion is a coordinated process, not a cleanse. Persistent pain, bleeding, major bowel changes or unexplained weight loss deserve medical assessment rather than dietary guesswork.