Digestion
The mechanical and chemical processes that break food down into absorbable nutrients, from the mouth through the stomach to the intestine.
Digestion is an orchestrated journey:
- Mouth: chewing + salivary amylase (starch digestion begins)
- Stomach: hydrochloric acid + pepsin (protein), churning
- Small intestine: pancreatic enzymes + bile, absorption of nutrients
- Colon: fermentation of fibre by the microbiota, reabsorption of water
An original angle (digestion starts in the head): a little-known fact: digestion begins before you even eat, in the « cephalic phase ». The sight, smell or even the thought of food triggers salivation and the secretion of gastric juices. The brain « prepares » the ground.
This is why mindful eating matters: eating stressed, standing up or distracted by a screen disrupts this cephalic phase and the whole of digestion (stress activates the sympathetic nervous system, which puts digestion on « pause »; you only digest well in « rest and digest » mode, the parasympathetic state).
Chewing, an underrated step: chewing well (20 to 30 times) is not a detail. It:
- Breaks food down mechanically (less work for the stomach)
- Mixes in salivary amylase (pre-digestion of starch)
- Sends satiety signals (eating fast means eating too much, as the signals arrive about 20 minutes late)
- Reduces bloating and discomfort
Timing: complete digestion takes 24 to 72 hours depending on the food. Fibre speeds up transit; fats slow it down (prolonged satiety). Transit that is too fast (diarrhoea) or too slow (constipation) affects absorption and the microbiota.