The unknown 'anti-nutritional table' of legumes, vegetables to be aware

Making the purchase well has its secrets, and among the most important is to know how to read the nutritional label of the products. How much fat does this cheese have? How much sugar does that fried tomato have? How many vitamins are in the yogurts? But most of the chemical compounds that contain food does not appear on the list, although some directly influence the nutritional quality of the foods we take home. There is no "anti-nutritional label", but antinutrients exist, and these chemical compounds make it difficult for the body to assimilate nutrients from the diet. They are in fruits and vegetables, in legumes, in whole grain cereals (those that are really whole grains), in eggs, seeds, pure cocoa and even black tea: in the last two, in the form of tannins.

Most antinutrients are the result of a silent war that plants wage with the world, they are part of the tens of thousands of compounds that it seems that these living beings have developed only to defend themselves their enemies natural, that what they want is to eat them. "They are phytochemicals, substances that exercise plant protection functions against external environmental factors," explains the professor of nutrition and bromatology at the University of Zaragoza Iva Marques.

Ways of sabotaging the nutritional quality of our food are diverse. The avidine of the egg white and the niacinogen of the maize bind to other substances of the food with an undesirable result: they inactivate the vitamins; the obese in many fruits and vegetables block iodine, which is part of the structure of the thyroid glands; oxalic and phytic acids, present in foods such as spinach, beetroot and chard, bind in the gut to minerals such as iron, zinc and calcium and prevent their absorption. There are also antinutrients that inhibit proteases and amylases, which are enzymes that catalyze the reactions needed to digest proteins and carbohydrates. Enzymes accelerate biochemical processes needed for digestion and if they disappeared they would be so slow that they would become ineffective

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Biochemical strategies of antinutrients are as varied as our weekly menu should be, which is precisely the best way to prevent them from exerting a negative influence. "In a diet complete and varied, the antinutrients do not have a significant impact because they are in many different foods and we are supposed to vary the intake throughout the week, the month and the year, thus disappearing their possible adverse effect, that would happen if we were to interit in high quantities every day," Marques says. But we don't necessarily have to think about increasing the range of food we put in the pantry, because variety is not the only defense we have against them. Humans have developed an unparalleled defense throughout the animal kingdom,

In the heat of the stoves, the contest is in our favor

The struggle for plant life in the face of the voracity of the outside world (it should not be forgotten that they are our main sources of energy, in the form of carbohydrates) goes beyond antinutrients. Vegetables, over millions of years of evolution, have come to manufacture venoves such as glucosinolates, biochemical weapons unique to plants of the order of the Brassicales, to which belongs for example broccoli (which has its own cabbage, watercress and capers, and they mean death for some small animals. Not so for some types of butterfly, which have developed a defense that turns poison into the food of their buds. In a similar way, humans have been able to disable the effect of antinutrients in order to access the numerous nutrients of plants  thanks to an invention that no other animal masters: the kitchen.

Cooking and soaking food are the two basic techniques for inactivating antinutrients. "First, soaking causes them to go into the water, then the cooking temperature turns them off because it changes their chemical structure," Marques explains. This process is essential to remove antinutrients from legumes (they all have these types of substances), although it is difficult to think of eating them otherwise... In what there is not so much consensus is that must be soaked whole grains, precisely those that are considered healthier because of their high fiber content, but it is a recommended practice. "Whole grain cereals such as rice, oats and rye should be soaked and then cooked like rice, or taken directly soaked, as in the case of oats and rye," Marques recommends.

It is also advisable to cook some vegetables such as spinach if consumed regularly and in large quantities, an important information for people who follow a diet based on raw vegetables. "In today's society, antinutrients can be a problem in a cruvegan diet that is unbalanced and monotonous," says the expert. According to her, if the routine is to repeat the same foods, especially raw and unsoaked, "it may be important to choose foods with good bioavailability of nutrients and less antinutrients, such as cabbages and the whole family of cruciferous, which they have good calcium availability because they contain little of their antinutrient par excellence, oxalic acid."

Another technique that deactivates antinutrients is fermentation, but even if it is used or soaking, the presence of antinutrients is higher when one takes the foods always raw. Germination is also an important process, as it removes the antinutrients present in the seeds, But antinutrients aren't always a piece of food chemistry that needs to be disposed of sooner or later,

What if they also oppose heavy metals?

Facing the Manicism in which some of the most noble human activities can, and often fall, the collective action of scientific research is characterized by illuminating fields of knowledge rich in nuances. Antinutrient is no exception. It is true that the unwanted action of these compounds is taken into account in the production of processed foods, both for human consumption and livestock that we then consume,

"Currently, this concept is used and manipulated importantly in feed to feed the cattle, for example, to which are added enzymes that destroy phytic acid, an antinutrient that blocks the absorption of iron; it is important that animal feed has nutrients with high bioavailability," explains dietitian-nutritionist. As for human food, "they are important and are controlled when preparing formulas or food for malnourished people in developing countries, or for emergencies," he adds. But it is also true that positive effects on these substances are beginning to be seen,

"Today it is known that, in small amounts, some of them also have beneficial effects for our organism", concludes Marques. There are publications on experiments carried out on cell cultures and also on animals that show that the phytic acid quela, that is, traps heavy metals in the large intestine, and that it has a protective effect on these cells, says Expert. "A hypolipidizing effect has also been observed, i.e. lowering the level of blood lipids, but the mechanisms behind it are still being investigated," Marques says. Regarding tannins, the dietitian-nutritionist emphasizes that they have a very high cellular protective potential for their antioxidant capacity and that an anti-inflammatory and antimicrobial biological activity has been described. And on saponins, another common group of antinutrients, it emphasizes that it has been observed to be involved in decreasing intestinal cholesterol absorption, and therefore contributes to lower blood cholesterol values. It wasn't all going to be bad,