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.