"Fibre" means plant components which are little or not at all broken down and digested by human beings.
Such components are heterogenic carbohydrate complexes such as fructo-oligosaccharides (garlic, onion, leeks, oats, chicory roots, etc.), pectins (strawberries, pears, apples, etc.), gum (guar, xantham), cellulose and lignin (green vegetables, pulses, cereals).
Unlike foods rich in simple carbohydrates or "sugars", fibre gives the foodstuffs that contain it a lower glycemic index (GI), which means that consuming such foods only slightly increases the blood sugar level, unlike white sugar for example. Just as with so-called fast-release foods, white sugar causes the blood sugar level to rise up sharply shortly after consumption, encouraging the rapid and sustained release of insulin, which in turn causes a rapid fall in the blood sugar level, triggering a hypoglycemic reaction.
For example, while white sugar has a glycemic index of 100, dried figs, rich in fibre, have a GI of just 40, with oleaginous fruit (almonds, walnuts, hazelnuts…) leading the way with a GI of 15.
Seasonal fibre on your plate
While summer is rich in high-fibre fruit and vegetables, when autumn arrives use the forgotten pulses which also have interesting alkalising properties: white, black, red or coco beans, flageolets, chick peas, split peas, lentils...
Different types of fibre with multiple health effects
According to their digestibility, different fibres are classified as:
- Insoluble fibre (IF), non-digested, which remains in suspension and expands in our intestine promoting speed of transit (cellulose, lignin)
- Soluble fibre (SF), partially digested, which form thick solutions or gels which slow down gastric emptying and modulate transit (pectin, gum)
Effect on the intestine
The two types of fibre share high absorption and water retention power, hence their role in regulating transit. 1 gram of fibre can absorb 3 to 25 times its own weight in water!
Most fruit and vegetables contain variable proportions of both types of fibre.
For example, 100g of prunes, one of the fruits with the highest fibre content, contains 7.8g of IF
and 5.2g of SF.
While insoluble fibre (green vegetables, fruit, wholegrain or semi-wholegrain cereals) is known to accelerate transit, soluble fibre (artichoke, onion, bananas, asparagus, chicory root) has a prebiotic role: it acts as food for certain intestinal bacteria which are beneficial to the body.
By encouraging the colonisation of our intestine by such bacteria (bifidobacteria, lactobacilli), it produces particular fatty acids, vital for the regeneration and repair of the intestinal mucous membrane.
"Fat trap" effect
Insoluble fibre generally has a high fat retention capacity. For example, wheat fibre (98% insoluble fibre) is able to retain 2 to 3 times its weight in oil, giving it a cholesterol-lowering effect.
After eating a meal rich in fibre, you will feel much fuller than compared to a meal low in fibre.
Effect on the carbohydrate metabolism
Different studies show that the consumption of fibre reduces hyperglycemia and hyperinsulinemia after a meal.
Vary your favourite breads
The consumption of bread has fallen sharply and yet it offers plentiful fibre if wholegrain or semi-wholegrain!
Fibre content in g for 100g
|GI white flour = 85
|GI wholemeal flour = 60