Fibers and laxative action
What are
Almost all vegetables, or rather vegetables, belong to a group of foods with laxative properties.
"Laxative food" means a food capable of stimulating intestinal evacuation (defecation) through the direct or indirect incentive of peristaltic motility / contraction.
Intestinal peristalsis
Intestinal peristalsis is a rather complex and articulated system: let's try to explain its fundamental points to better understand the mechanism.
Peristalsis is nothing more than a set of muscular contractions of the intestinal tube, aimed at segmenting and advancing the product of digestion. The segmentation and advancement contractions are different but both are indispensable.
How they act
Basically, laxative vegetables promote two useful conditions for the evacuation mechanism:
- Increase of the fecal volume by dissolving the water-soluble fiber: this phenomenon allows to optimize the bowel contraction and to constantly advance the faeces contained in it
- Increase in gases due to probiotic fermentation of the insoluble fiber: the gases, by pressing against the walls of the digestive tract, favor a reflex contraction that increases the transit
The vegetables consist essentially of vegetables, of which the leaf, the root, the flower or the tuber is consumed; the laxative property of vegetables derives above all from the quantity of dietary fiber, a fundamental nutritional component for maintaining cleanliness and intestinal integrity. Some vegetables that promote the secretion of bile, such as artichoke and chicory, have a mild purifying and laxative effect linked to these cholagogic and choleretic properties, and mediated by the action of bile acids not reabsorbed by the intestine.
Having said this, it is easy to understand that the most laxative vegetables are those characterized above all by the greater quantity of fiber, or those that have larger portions for consumption; a classic example is that of cooked chard, whose portion is about 150-250 g, compared to fresh lettuce, which is instead consumed within 50-100g.
We also remember that, in addition to the consumption of laxative vegetables, to optimize the regulation of the alvo it could be useful to also follow other tricks; first of all it is essential to drink frequently to guarantee body hydration, as systemic dehydration also causes fecal dehydration; secondly, the consumption of other foods favoring bowel cleansing should also be promoted; among these we mention: warm milk, honey, vegetable oils, tamarind jam, cassia syrup, and many others.
What are they?
Assuming that the hydration is optimal and that the colon is not irritated, the vegetables characterized by the greater laxative power induced by dietary fiber could be those shown in the table. Also asparagus, chicory, cauliflower, spinach and green beans are commonly considered vegetables with laxative action.
| Food | Fiber (g) |
| Artichokes | 5.5 |
| Brussels sprouts | 5.0 |
| Field chicory | 3.6 |
| carrots | 3.1 |
| broccoli | 3.1 |
| Leeks | 2.9 |
How many vegetables?
In the case in which the laxative vegetables are consumed together with other foods of vegetable origin (cereals, legumes and fruit), it would be good practice to consider that the quantity of dietary fiber introduced daily is equal to the sum of that contained in all foods of vegetable origin . In order to avoid a possible excess of fiber it is necessary to keep the portions consumed within the limits of national guidelines and correct the diet based on individual susceptibility.
In principle it is possible to define that the right consumption of vegetables (both laxative and non-lax) must necessarily be daily, with a frequency of at least two portions / day. The latter vary according to the type of vegetable and the method of consumption; for a cooked vegetable it is possible to use a weight (raw) of at least 150g (artichokes, Brussels sprouts, chicory, etc.), while for a raw leaf at least 50g (lettuce, radicchio, valerian, rocket, etc.), and finally, for a raw vegetable root, or any one of high consistency, at least 100g (turnips, carrots, beets, leeks, etc.).
If necessary, it is advisable to increase the portions of laxative vegetables a little at a time, in order to avoid the undesirable effects related to excess dietary fiber (reduced nutritional absorption, diarrhea, meteorism, etc.) and anti-nutritional components (oxalates and phytates).
