What are Antinutrients?

If you’ve heard of the term antinutrients, you’ve likely heard they have the potential to be harmful to our health. But what are antinutrients? What foods contain them? How can you reduce them and are they actually harmful? Here is everything that you need to know about antinutrients.

What are antinutrients?

Antinutrients are compounds naturally found in food that impair digestion and nutrient absorption. All foods contain nutrients, however, certain plants; including grains, seeds, nuts, and legumes, contain compounds that act as a form of natural defense mechanism. The presence of these compounds in plant foods can decrease their absorption of essential amino acids, vitamins, and minerals.

Why do antinutrients exist?

Antinutrients help to protect plants from infection or consumption by animals and insects. Unlike animals, which can run away, swim away, or fight their prey, plants cannot move and, therefore, use natural or synthetic compounds known as antinutrients, that can be harmful or deadly to various organisms, to protect themselves.

Types of Antinutrients

The most well-known antinutrients in plant foods include:

Phytates (Phytic Acid)

Phytates, also known as phytic acid, is the most common antinutrient found in grains and legumes. Found in the hulls of nuts, seeds, and grains, it has a strong binding affinity for calcium, zinc, magnesium, iron, and copper, which can limit their nutrient absorption (1, 2).

Lectins

Lectins are found in all plant foods but are present in greater amounts in grains and legumes and can interfere with the nutrient absorption of calcium, iron, phosphorus, and zinc (3).

Oxalates

Oxalates and oxalic acid can bind to calcium, limit absorption in the body, and may increase the formation of kidney stones from calcium oxalate. Oxalate-rich foods include green leafy vegetables, such as spinach and Swiss chard, rhubarb, cereal grains, cocoa, nuts, and seeds (1, 4).

Tannins

Tannins are antioxidant polyphenols found in food and beverages, including coffee, tea, some fruits, and cocoa, and can impair digestive enzymes, protein digestibility, and iron absorption (5, 6).

Glucosinolates (Goitrogens)

Glucosinolates, also known as goitrogens, are found in cruciferous vegetables; including broccoli, Brussels sprouts, cabbage, and cauliflower, and are widely recognized for their interference with the uptake of iodine and flavonoids and their ability to chelate metals such as iron and zinc, thus reducing their absorption (5).

Saponins

Saponins are mainly found in legumes, have a bitter taste and soapy texture, and can impair the digestion of protein, and uptake of vitamins and minerals in the gut (6).

Foods with Antinutrients

All plant-based foods contain antinutrients. Various antinutrients can be found in grains, legumes, roots, nuts, seeds, vegetables, and fruits (6, 7).

Antinutrient	Foods	Potential Implication
Phytic Acid	Legumes, cereal grains, pseudo-grains, nuts, seeds, nightshades	Reduce mineral absorption
Lectins	Legumes, grains, pseudo-grains, nuts, seeds, fruits, vegetables	Inhibit nutrient absorption
Oxalates	Legumes, cereal grains, nuts, tubers, green leafy vegetables	Inhibit calcium absorption
Tannins	Legumes, tubers, nightshades, fruits, cocoa, tea, coffee	Impair digestive enzymes and iron absorption
Glucosinolates	Brassica vegetables, pseudo-grains, tubers	Inhibit iodine absorption
Saponins	Legumes, pseudo-grains, nightshades	Inhibit nutrient absorption

Which foods have the most antinutrients?

Antinutrients are found in their highest concentrations in grains, beans, lentils, and nuts, however, can also be found in some leaves, roots, tubers, and fruits of certain plants. Some of the most consumed antinutrient-containing foods include soybeans, whole grains (including wheat), chickpeas, beans, lentils, nuts, seeds, spinach, kale, broccoli, peppers, eggplants, tomatoes, chocolate, and tea.

Are antinutrients safe?

Although most plant foods contain antinutrients, when properly prepared, they are safe to consume (7). In fact, some antinutrients have been shown to provide health benefits, for example, phytic acid has been found to lower cholesterol, slow digestion, and prevent sharp rises in blood sugar (8, 9).

Moreover, most antinutrients can be removed or deactivated by soaking, sprouting, or boiling before consumption, and some traditional methods of food preparation, such as fermenting, have been shown to increase nutritional value (10).

How to Reduce Antinutrients in Foods

Many traditional methods of food preparation are known to reduce antinutrients and increase the nutritional value of plant foods. The following processing methods can be used individually or in combination to reduce the impact of antinutrients.

Soaking

Soaking grains, beans, and legumes in water before preparation is a simple yet effective way to deactivate enzyme inhibitors (11). Many of the antinutrients are found in the skin and are water-soluble and, therefore, dissolve in water. For example, soaking whole grains in water overnight or in water with an acidic medium such as lemon juice or cider vinegar can help to neutralize phytic acid. Soaking is often used in combination with sprouting, fermenting, or boiling.

Sprouting

Sprouting, or germination, is one of the most effective ways to deactivate antinutrients in plant foods, specifically phytic acid and lectins. Given most antinutrients are part of the seed’s system of preservation – preventing sprouting until the conditions are perfect –  the process of sprouting grains, legumes, and seeds helps to reduce their level of phytic acid and tannins and increase their nutrient availability (6, 11).

Fermenting

Fermentation is a traditional method of food preservation and preparation that has been used across cultures. The process of fermentation helps to decrease the level of phytic acid and lectins while increasing beneficial bacteria and nutritional value at the same time (6, 11).

For instance, fermenting soy into tempeh or miso, cabbage into sauerkraut or kimchi, and whole grains into sourdough bread help to make the foods more easily digested and micronutrients more available. Moreover, fermented foods are sources of probiotic bacteria which have been shown to promote a healthy balance of gut bacteria and have a wide range of health benefits.

Boiling

Cooking food at high heat has been shown to decrease levels of lectins, tannins, and protease inhibitors in plant foods (12). While boiling whole grains, boiling legumes, boiling or steaming Brussel sprouts, cauliflower, and leafy greens have specifically been shown to significantly decrease their levels of oxalates and glucosinolates (11).

Antinutrients FAQs

The Bottom Line

Antinutrients are natural compounds found in plant foods, including whole grains, beans, lentils, nuts, seeds, and some vegetables, that can interfere with the absorption of other nutrients. Although antinutrients can make certain foods more difficult to digest and their nutrients less bioavailable, when properly prepared via soaking, sprouting, fermenting, and boiling, antinutrient-containing foods are generally not of concern and can be consumed in a healthy diet.