By definition, fibers are substances of plant origin that are neither digested nor absorbed by our digestive tract. However, our intestinal flora, by degrading them, allows us to absorb the carbohydrates in a variable and partial way, hence their contribution to the tune of 2 cal / g in our energy intake.
In addition to their effects on our transit, they would also reduce our energy intake by 5 to 10% (satiating effect of fibers), to reduce our total cholesterol level by 10 to 15% (but it is necessary in large quantities) and to limit the increase in glycemia (blood sugar level) after a meal. By slowing the digestion and absorption of sugar, soluble fiber helps us fight cravings. Certain minerals such as calcium or phosphorus are less well absorbed if the diet is too rich in fiber. So be careful if you have mineral deficiencies (magnesium, calcium …) or if you consume a lot of refined fibers (such as bran for example) to boost your lazy transit: be sure to enrich your diet with sources of minerals (pulses) and green vegetables in particular) and drink enough because otherwise, instead of facilitating the transit, they will form a plug. Finally, fibers would prevent the appearance of certain cancers.
Soluble and insoluble fiber are different.
The former are said to be soluble because they dissolve in water. In the intestine, they cause the intestinal bolus to swell, giving it a viscous consistency that facilitates intestinal transit. They are found in oats, barley, dried fruits (prunes, dates, figs …), fresh fruits (currants, raspberries, blackberries, pears and apples with the skin …), fresh vegetables (Brussels sprouts, celeriac, broccoli, chervil …) and dried (red beans, chickpeas, lentils …).
The second, called insoluble, absorb large amounts of water and increase the weight of the stool, its water content and plasticity. They thus fight against the constipation, provided you drink well. They are found in wheat bran, whole grains, wholemeal bread …
How can we meet our daily fiber needs?
25 to 30 g This is the amount of fiber that an adult should consume each day according to the recommendations of the National Health Nutrition Program (PNNS), while most women and men absorb half as much on a daily basis.
Our daily fiber needs are 40% met with a 40g bowl of All Bran cereal, 50% with 6 slices (160g) of wholemeal bread or 400g of cooked peas, and 25% with 2 to 3 dried prunes or 300 g of broccoli or 100 g of raspberries.
