Antinutrients
Humans evolved eating a wide variety of plant foods. For millennia, our ancestors developed ways to process fruits, nuts, seeds, greens, and tubers—transforming them into safe, nourishing staples.
Walnuts are packed with healthy fats, but also antinutrients like phytates and oxalates. Learn how to prepare them for better nutrient absorption.
Beyond the nectar and fruit that plants produce for assisted reproduction, they don’t want to be eaten. To defend themselves, many evolved antinutrients that can discourage predatory animals from eating them. While small amounts of these compounds may offer benefits, overconsumption can lead to nutrient depletion and chronic symptoms, especially for diets high in grains, legumes, nuts, seeds, or vegetable smoothies.
What Are Antinutrients?
Antinutrients are naturally occurring compounds in plants that can block nutrient absorption, irritate the gut, interfere with digestion, or contribute to food sensitivities. Here are some of the most common types:
Glycoalkaloids
Found in nightshades such as potatoes, tomatoes, and eggplant, glycoalkaloids are natural pesticides. In high amounts, they can cause digestive distress—or, in rare cases, toxicity. They are most concentrated in green or sprouted potatoes.
Reduce with: Peeling, fermentation, and avoiding damaged or green produce.
Lectins
Lectins are a class of proteins found in many plants. They tend to be higher in legumes (beans, chickpeas, lentils, peanuts), grains (wheat and barley), nightshades (tomatoes, eggplant, and bell peppers), and cucurbits (cucumbers, squash, and pumpkin seeds). They can bind to the gut lining, impairing digestion and nutrient absorption. Individual tolerance varies.
Reduce with: Soaking, boiling, fermenting, and pressure cooking.
Oxalates (Oxalic Acid)
Oxalates are found in leafy greens like spinach and chard, as well as in nuts and seeds. They can bind with calcium to form crystals, potentially contributing to kidney stones or joint pain.
Reduce with: Boiling and discarding the water, fermenting, soaking, and pairing with calcium-rich foods such as dairy.
Phytates (Phytic Acid)
Common in grains, legumes, nuts, and seeds, phytates bind to minerals like calcium, magnesium, zinc, and iron, reducing their absorption.
Reduce with: Soaking, sprouting, and fermenting.
Sunflower seeds are naturally high in phytic acid, a compound that can bind minerals and reduce their absorption. Soaking the seeds overnight, then draining and rinsing, may help reduce phytic acid levels and improve mineral bioavailability.
Tannins
Tannins are antioxidant polyphenols found in tea, wine, legumes, and some fruits and nuts. They can interfere with the digestion of proteins and reduce iron absorption.
Reduce with: Soaking and boiling.
Protease Inhibitors
These compounds interfere with protein digestion by inhibiting key digestive enzymes. Found in grains (such as wheat, rye, and barley), legumes, and some fruits and vegetables including apples, bananas, spinach, cabbage, and tomatoes.
Reduce with: Soaking, sprouting, boiling.
Saponins
Saponins are bitter, foam-producing compounds found in legumes, quinoa, and some leafy greens. They can irritate the gut lining and may have detergent-like effects on cell membranes when consumed in large amounts. (For this reason, I would suggest that aquafaba from chickpeas might not be ideal to consume, despite its popularity in plant-based cooking and among gastronomes.)
Reduce with: Vigorous rinsing, soaking, and scrubbing—particularly important for quinoa and certain beans. Discard soaking water before cooking.
Traditional Techniques to Tame Antinutrients
Throughout history, traditional food cultures developed effective ways to neutralize antinutrients—methods that are simple to replicate at home:
Boiling and Blanching
Best for oxalates, lectins, tannins, and protease inhibitors. These water-soluble compounds leach into cooking water, which should be discarded. While effective, boiling can reduce water-soluble vitamins like B and C, so it’s best used in combination with other methods.
Soaking and Sprouting
Ideal for reducing phytates, lectins, protease inhibitors, and saponins. Soaking seeds, grains, nuts, and legumes in warm, salted water mimics natural germination, activating enzymes that begin breaking down protective compounds. Sprouting enhances these effects and can boost overall nutrient availability.
Fermentation
A powerful method to reduce phytates, lectins, and some oxalates. Fermentation introduces beneficial microbes that pre-digest and break down antinutrients while enhancing gut-friendly probiotics. Examples include sourdough bread, fermented vegetables, miso, and tempeh.
Scrubbing and Rinsing
Especially effective for saponins. Thoroughly rinsing quinoa or scrubbing legumes before cooking can significantly reduce their bitter, irritating compounds. Combine this with soaking for best results.
Smart Food Pairing
Strategic combinations can offset the effects of remaining antinutrients. Calcium-rich foods such as yogurt or kefir can bind to oxalates, reducing their absorption and supporting mineral balance. Iron that’s otherwise inhibited in phytate-rich foods might become more available when vitamin C is included—for example, adding sauerkraut to a whole-grain meal.
Quick Guide to Reducing Common Antinutrients
Glycoalkaloids (potatoes, nightshades): Peel, ferment, and avoid green or damaged produce.
Lectins (beans, lentils, wheat, nightshades): Soak, boil, ferment, or pressure cook.
Oxalates (spinach, nuts, seeds): Boil and discard water, ferment, pair with calcium-rich foods.
Phytates (grains, legumes, nuts): Soak, sprout, ferment, eat with vitamin C-rich foods.
Tannins (tea, wine, legumes): Soak and boil.
Protease Inhibitors (grains, legumes, fruits): Soak, sprout, boil.
Saponins (quinoa, legumes): Rinse thoroughly, scrub, soak, and discard soak water before cooking.
Final Thoughts: The Power of Preparation
Antinutrients are not inherently harmful—in fact, some may offer benefits in moderation, such as antioxidant or anti-inflammatory effects. But when consumed in excess, especially in diets that rely heavily on improperly prepared plant foods, they can contribute to nutrient depletion, digestive distress, and long-term imbalances.
Fortunately, traditional preparation methods like soaking, sprouting, fermenting, and food pairing allow us to make the most of what plants have to offer—reducing what harms and preserving what supports us.
It’s also worth remembering: when plants are grown in healthy soil, harvested at peak ripeness, and eaten in season, they tend to be more flavorful, digestible, and nutrient-dense. Colorful, seasonal plant foods provide a wide array of beneficial phytonutrients when we prepare them thoughtfully.
