By Philippe Mathelet
Chemical transformation of food
Chemical transformation of food: understanding this mechanism and the different organs involved
The transformation system
After the path of food described in a previous article, let us now study the chemical transformation of food.
This requires three reactions:
- protides (proteins) are broken down into amino acids
- lipids (fats) are emulsified and converted into fatty acids
- carbohydrates (sugars) are transformed into assimilable sugars.
Digestive enzymes serve to cut food into increasingly smaller substances.
Saliva mixed with food (1.5 litres per day) contains an enzyme that splits starch.
Gastric acids mix with the food bolus to break it down while mucus deposits on the stomach walls to protect it.
The thus pre-digested food passes into the small intestine through the pylorus at the base of the stomach.
Arriving in the Duodenum, the most important place of digestion, the food undergoes the action of three digestive juices: intestinal juice, pancreatic juice and bile.
Enterokinase contained in the intestinal juice will activate other enzymes (sucrases, maltases, lactases, peptidases).
Moreover, Secretin will neutralise gastric acidity in association with bile arriving via the common bile duct.
The Pancreas is an accessory gland of the digestive system that produces about two litres of juice per day, containing several enzymes allowing the breakdown of proteins, fats and starch (Trypsin and Chymotrypsin breaking down proteins, Lipase dealing with fats and Amylase completing the hydrolysis of starch).
Bile is secreted depending on fats and minerals in the stomach and Duodenum, bile salts combining with lipids to become soluble in the blood.
The intestinal flora transforms urea into ammonia and participates in the fermentation of carbohydrates not absorbed by the small intestine in order to allow waste evacuation. The small intestine is therefore the main organ for nutrient absorption, a process facilitated by its length and by its villi which develop a large exchange surface (about 250m2).
Cells of the intestinal wall and the very dense network of blood and lymphatic vessels allow the passage of digestion products into the internal environment of the organism.
Absorption will be more or less selective depending on the needs of the organism, minerals and vitamins undergoing no transformation.
These articles are for information only and are neither medical advice, nor a diagnosis, nor a prescription.
The articles in this section reflect the experience and reading of their author, who does not practise any medical profession. They are published for information and never replace a consultation with a doctor or pharmacist. Food supplements are not medicines. If you are under treatment, pregnant, breastfeeding or ill, ask a health professional before any use.