The more we become aware of the benefits of consuming more plant-based foods, the more important it is to control our consumption of antinutrients.
What is anti-nutrients?
Although some are artificial, most antinutrients are natural molecules produced by plants and animals that prevent the absorption of nutrients and essential amino acids from other foods. Antinutrients are a particular issue for people who adopt a vegetarian diet, as the consumption of a large amount of these foods can lead to nutrient deficiencies and, in extreme cases, malnutrition.
This is because antinutrients can exacerbate food intolerances and health problems such as heartburn, acid reflux, Crohn's disease, and irritable bowel syndrome. That said, antinutrients also have some health benefits. That is why it would be unwise to completely eliminate them from our diet.
The most common anti-nutrients
There is a wide variety of anti-nutrients, but the most common are:
Phytate (phytic acid)
Tannins (tannic acid)
Lectins
Protease inhibitors
Oxalates
Phytate (phytic acid)
Seeds, cereals, nuts, and legumes store phosphorus in the form of phytic acid in their husk, in the form of phytin or phytate salt.
Phosphorus stored as phytic acid can be released during the digestion of the plant matrix by the digestive enzyme phytase. This enzyme is not made by the human body, but it is produced in the stomach of ruminants that derive their energy only from plants.
In the absence of phytase, phytic acid can prevent the absorption of other minerals such as iron, zinc, magnesium, and calcium. Not being digested, it passes intact through the human digestive tract.
Germination or lactic fermentation breaks down phytic acid, which helps recover minerals stuck in food and makes plant components easier to digest. These techniques are effective ways to combat antinutrients in a variety of plant-based foods.
Tannins (tannic acid)
Grapes and green tea are rich in this bitter-tasting water-soluble polyphenol, which is also an antinutrient.
Tannins have been shown to impede the digestion of various nutrients by reducing the efficiency with which the body can benefit from other bioavailable substances.
However, tannic acid also has important antioxidant properties, which help protect cells from free radical damage.
Tannic acid is usually broken down during the fermentation of grape juice to obtain wine or when heating green tea.
Lectins
Lectins are a category of proteins found in almost everything, including our bodies!
Seeds, legumes, grains, beans, potatoes, and dairy products are all sources of lectins, although only about a third of all the foods we usually eat contain really significant amounts of these proteins.
Lectins bind to carbohydrates in cell membranes and can be toxic at sufficiently high concentrations (ricin, a powerful nerve agent, is a good example). They also cause gastrointestinal problems.
In plants, it is thought that these substances play a role in their protection against external aggressions, but that they may also have participated in their evolution as a means for plant seeds to pass through the digestive systems (without being degraded) and be dispersed.
The American doctor Steven Gundry suggests in his book "The Plant Paradox"(1) that lectins have consequences on our microbiota: they are harmful to the intestinal walls and cause digestive problems (diarrhea and vomiting). This hypothesis is supported by a systemic review(2) published in 1999 revealing that the consumption of foods rich in lectins, undercooked or undercooked, can cause digestive disturbances.
Some lectins are also thought to contribute to inflammatory bowel disease, diabetes, rheumatoid arthritis, and celiac disease. They are also part of the nutrients to avoid in case of irritable bowel syndrome.
Although they are currently controversial, there is little scientific evidence to determine whether we should avoid foods containing lectins. In the meantime, the same techniques can help reduce the concentrations of lectins like other antinutrients.
Protease inhibitors
Many of the foods we reviewed above (seeds, grains, legumes) also contain substances that inhibit protein absorption from other foods when ingested.
They work by preventing or blocking the action of proteases, enzymes that break down long.
Oxalates
Oxalates are natural molecules commonly found in plants. In the presence of metal ions, they form solid precipitates.
If oxalate manages to enter the body, it can form calcium oxalate, a particularly problematic crystal, because its accumulation is responsible for kidney stones.
To prevent oxalate damage, it must be prevented from being absorbed by the body. This is possible thanks to calcium.
What makes oxalates actually pose few problems is that most of the plants that are rich in them (leafy green vegetables like spinach) are also rich in calcium or magnesium.
Antinutrients of circumstance
In addition to the antinutrients found in nature, certain supplements or foods rich in beneficial nutrients can cause reactions of an anti-nutritional nature when taken in sufficient quantities.
For example, the consumption of large quantities of tea (more than 1 l/day)(5), red wine, olive oil, chocolate, and coffee inhibits iron absorption.
Similarly, grapefruit, for example, can prevent the body from absorbing certain medications. For this reason, some warnings about food interactions appear on medical labels.
However, a varied diet reduces the incidence of this type of interaction.
Disable antinutrients
Soaking and cooking disable or reduce the action of antinutrients in food, as many of them are soluble in water or degrade with heat. This is one of the reasons why you can eat red beans and soybeans, cooked, for example, but not raw.
Similarly, fermentation is a powerful natural tool for breaking down antinutrients and improving the digestibility and nutritional profile of many plant-based foods.
Take flavonoids, for example, which are linked to the production of plant pigments in tea, coffee, and other plants. These polyphenolic compounds have proven antioxidant and antimicrobial properties.
Indeed the combination of oxalate in the intestines prevents its absorption in the body.
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