Five portions of fruit and vegetables a day, whole grains, legumes… but in the end we don't risk exaggerating with all these fibers? "The 25 grams indicated in the Larns (the Reference Intake Levels of Nutrients and Energy established by the Society of the Country of Human Nutrition) represent the minimum amount to enjoy the benefits of fiber, including the prevention of colon cancer, first of all, but also that of liver cancer, as shown by a study published in the Annals of Oncology », explains Professor Francesco Marotta, del Department Human Nutrition, Texas University.
But is there a quota of fibers to be taken and not to be exceeded? "No precise limit has been set»Replies the expert. «The more we eat, the more we should proportionally increase the amount of fiber, arriving up to 30-35 grams. However, it seems that beyond this limit there may be more risks than advantages, first of all that of depleting ourselves of vitamins and minerals.
NOT ALL FIBERS ARE THE EQUAL
A study has revealed one decrease levels of betacarotene caused by an excessive intake of soluble fiber. Yes why not all fibers are the same. Soluble or insoluble? Both cannot be digested. But while the former attract water, forming a kind of jelly, the others pass unaltered through the intestine, causing greater problems with fermentation and meteorism. Knowing these differences is essential if you want to use fiber to keep hunger at bay, fight constipation, deflate the abdomen.
- 1. Keep hunger at bay with soluble fiber
If you want to avoid hunger pangs, the best fibers are those soluble (pectin, mucilage), because they "fill" deceiving the appetite. The stomach has only pressure receptors: the more its walls are stretched, the more full you feel and the more the release of cholecystokinin, a hormone that slows gastric emptying, increases.
An hour before main meals it may be useful to take a sachet of galactomannans (a type of soluble fiber), dissolved in water at room temperature. The feeling is that you have eaten 200-300 g of food while in reality you have only eaten 10 g of fiber and 290 g of water. Thus, with a full stomach, appetite is curbed and you avoid binge eating as soon as you sit down at the table.
At the beginning of the meal it is good to have a salad of raw vegetables (seasoned with a little oil): it “steals” space for other foods and also, by providing a lot of insoluble fiber, it slows down (even if it does not prevent it) the absorption of carbohydrates, prolonging satiety.
- 2. Against constipation: watch out for insoluble fibers
Contrary to what one might think, the best way to regularize the intestine it is not eating wheat bran every day: this food (often added to yogurt or milk for breakfast) is consisting almost exclusively from insoluble fibers which irritate the digestive system, causing fermentation, meteorism and swelling the belly without achieving the desired result.
If you want to combat constipation, choose i instead foods that are a source of soluble fiber, those that swelling increase the fecal mass favoring its transit with sweetness. This type of fiber, by the way, has a function prebiotic: stimulates the balanced development of the intestinal flora.
Green light for oat flakes, barley soups, cooked vegetables, prunes. Yogurt and fermented milks enriched with probiotic enzymes which (like fibers) favor the well-being of the intestine can also be useful.
And if you want to help you with a supplement, choose from those that provide soluble fiber.
La cooking it makes the fibers less irritating, because it increases the quantity of the soluble ones. If you then blend them, you get two other advantages: they become more attackable by bacteria (thus improving their prebiotic function) and they hold more water (therefore, they increase the sense of satiety and speed up the intestine).
- 3. If you have a swollen belly ... blend the fibers
II swelling it is often the consequence of dysbiosis (ie the imbalance of the bacterial flora) as well as the inability of the intestine to eliminate the air that forms inside it. Sometimes, to achieve the goal of a flat abdomen, it is enough to favor the distension of the intestinal walls by resorting to supplements di fibers soluble (pectins + glucomannans). Particularly indicated when tension is associated with constipation, they can also help in cases of diarrhea (which in colitis often alternates with constipation) because, by retaining water, make the stool less liquid. In general, however, the first thing to do is to counteract abdominal swelling minimize insoluble fiberby eliminating whole grains and legumes from the diet. And most of the vegetables too. Apples and pears are the only fruits that do not cause problems.
To vary, you can indulge in a mixed smoothie: during preparation the fibers are chopped and therefore less irritating. Even among the vegetables the choice is limited. Raw only green salads with small leaves are good. Boil the carrots, courgettes, potatoes (cooking in water reduces the percentage of insoluble fiber). Ok also to the past, but without beans, the number one enemies of the sensitive gut.