As awareness grows for the benefits of eating more plant-based protein, so the importance of reducing our intake of antinutrients increases too.
What Are AntiNutrients?
Antinutrients are especially challenging for those choosing a predominantly plant-based diet since eating a lot of these foods can lead to nutrient deficiencies and, in extreme cases, malnutrition.
At the same time, antinutrients also provide some health benefits. For this reason it would be unwise to eliminate them from our diets altogether.
The Most Common AntiNutrients
There are a wide variety of antinutrients, however some of the most common are:
Phosphorus stored as phytic acid can be unlocked during digestion of plant matter by the digestive enzyme phytase. While humans don't create this it's produced in the stomachs of ruminants who obtain their energy solely from plants.
In the absence of phytase, phytic acid can impede the absorption of other minerals like iron, zinc, magnesium and calcium and passes through the human digestive tract intact.
Sprouting or lactic acid fermentation break down phytic acid, which releases locked minerals in food and makes plant-matter easier to digest. These techniques are useful tools to manage antinutrients in a range of plant-based foods.
Tannins (tannic acid):
Grapes and green tea are rich in this bitter-tasting, water soluble polyphenol, which also happens to be an antinutrient.
Tannins have been shown to impair the digestion of various nutrients by decreasing the efficiency with which the body can derive benefit from other bioavailable substances.
Tannic acid is typically broken down through the action of fermenting grape juice to make wine or heating green tea.
Lectins are a class of proteins found in almost everything - including our bodies!
Seeds, legumes, grains, beans, potatoes and dairy are all sources of lectins, though only about a third of all the foods we typically consume contain truly significant amounts of these proteins.
In plants it's thought they play a role in protecting them from external damage but may also have co-evolved as a means for plant seeds to pass through digestive systems and get dispersed.
While a current source of some debate, there is currently little scientific evidence to show whether we should avoid foods with lectin. In the meantime the same techniques can help lower concentrations of lectins as other antinutrients.
Many of the same foods we've reviewed above also contain compounds and proteins that inhibit the absorption of proteins from other foods when ingested.
These act by suppressing or blocking the action of proteases, enzymes that break down long-chain proteins into their constituent components through proteolysis.
Oxalates are natural salts or esters (acids) of organic compound oxalic acid, which are commonly found in plants can can also be synthesized in the body. In the presence of metal ions (atom compounds), they form solid precipitates.
Calcium oxalate is especially problematic as its accumulation is linked to kidney stones. This insoluble precipitate forms in leafy green vegetables rich in calcium, such as spinach, which can't be processed out of the urinary tract once processed through the digestive system. Rhubarb, beetroot and bran are also rich sources of calcium oxalate.
Despite its name, calcium actually binds to oxalates in the intestines and prevents calcium oxalate from being absorbed by the body. As a result diets rich in calcium prevent the oxalate from accumulating. Combining other calcium-rich foods with leafy greens is therefore a great way to prevent the oxalate form from causing harm.
In addition to antinutrients that are naturally produced, some supplements or foods rich in beneficial nutrients can create reactions of an antinutrient nature when taken in sufficient quantities.
For example calcium or calcium-rich foods and beverages can impede the absorption of iron if ingested at the same time as foods or this mineral supplement.
Similarly grapefruit, for example, can prevent the body from absorbing certain medications. This is the reason behind some food interaction warnings listed on medical labels.
Eating a varied diet lowers the incidence of these kinds of interaction.
Soaking and cooking disable or reduce the action of antinutrients in food since many are water-soluble or degrade with heat. This is one of the reasons why you can eat cooked kidney and soybeans, for example, but not raw ones.
Similarly fermentation is a powerful natural tool to break down antinutrients and improve the digestibility and nutrient profile of many plant-based foods.
For example heartburn and acid reflux, experienced by at least 20% of the population on a regular basis, can be triggered by antinutrient plant acids found in coffee beans and a range of other otherwise harmless and beneficial foods.
This is one of the reasons why eatCultured developed a special fermentation technique for Cultured Coffee and how our work with natural microbes helps improve the nutritional value of plant-based protein as well as their digestibility.
Are All Antinutrients Bad?
No. While antinutrients can be problematic, some may also provide health benefits.
Ultimately with such a range of antinutrients to investigate, many more helpful applications of these compounds may yet present themselves.
In the meantime fermenting, soaking, sprouting and heating foods, especially for those following plant-based diets, are simple and effective ways to control antinutrient intake.