Antinutrients - Should I Be Concerned?


Antinutrients are natural or synthetic compounds found in food, especially grains, beans, legumes, and nuts, that interfere with the absorption of certain vitamins, minerals, and other nutrients. An antinutrient's major role is to protect their natural “home”  (plant, root, or seed they inhabit). They are designed to repel pests, bugs, and other predators from eating the plant. Since plants don’t have legs and cannot run away from predators, they have a defense mechanism to ensure they can continue to grow and thrive. So in theory, antinutrients are a good thing; well, that is if you are a plant! But as we will unpack throughout this article, the human body is a “predator” and cannot properly digest these antinutrients. The plant’s defense mechanism is to fight against the digestive system and block the ability to fully breakdown food into it’s proper amino acids and nutrients. Antinutrients get their name from affecting the natural mechanisms of nutrient absorption. As you will learn below, eating large quantities of digestion-resistant foods (primarily grains) day after day can lead to inflammation and a weakened digestive system. The most common antinutrients include:

  1. Lectins
  2. Phytates (phytic acid)
  3. Tannins
  4. Oxalates (oxalic acid)
  5. Saponins

Although it may appear that antinutrients are a bad thing, under some circumstances they do have some health benefits. This is why they are so controversial. So how is one to know what antinutrients to avoid and which ones to consume? Let’s dive into each antinutrient and determine if it’s worth investing in!

1. Lectins

Lectins are carbohydrate-binding proteins found in all food plants, especially seeds, legumes and grains. Frequent consumption of these proteins can be harmful and damaging to the digestive system. They can stick to the cells in the lining of the small intestine and alter the texture. When over-consumed, grains and legumes (all beans, soy, and peanuts) can make digestion quite difficult. Although, all foods contain lectins, only about 30% contain significant amounts. Grains and legumes contain the most, followed by dairy, seafood, and nightshade plants (peppers, tomatoes, eggplant, and potatoes). When we consume grains and legumes we are actually eating the seed of the plant; this equates to eating hundreds, if not thousands, of seeds! Uncooked legumes are the largest source of lectins. I’ll be discussing how to properly prepare legumes in order to greatly reduce antinutrient levels towards the end of this article.

Conclusion: Concentrated amounts of lectins can cause damage to the intestinal wall and make digestion difficult. I recommend eating grains, beans, and other legumes in moderation, and if you have known digestive complications try to avoid them as much as possible. Dairy and nightshade vegetables have lesser amounts of lectins and only need to be tested for sensitivity in those with digestive complications, autoimmune disease, or other health complications relating to nutrient absorption.

2. Phytates

Phytates, also referred to as phytic acid, are indigestible, mineral-binding compounds found in grains, legumes, nuts, and seeds. Phytic acid is the most well-known antinutrient; it can prohibit phosphorus, calcium, copper, iron, magnesium, and zinc from being properly absorbed in our bodies. This is a big deal, as minerals are key players in every cellular function. Mineral deficiencies can result in a lot of symptoms from fatigue, muscle cramps, PMS, PCOS, constipation, asthma, migraines, and hormonal imbalances. Although phytates are found in all grains, legumes, seeds, and nuts they are not as high in seeds and nuts because the hard outer shell is removed prior to consuming; this shell is where the highest concentration of phytates reside as it is the plan’s first barrier. You may wonder why cows, sheep, goats, and buffalo can eat a grain based diet? It's because they are ruminant animals that possess phytase (the enzyme responsible for the breakdown of phytates). Despite the clear drawbacks to phytates there is some evidence that phytates may be protective against kidney stones and breast/prostate cancer. When phytic acid binds minerals in the gut, it can prevent the formation of free radicals, thus making it an antioxidant.

Source: Schlemmer U, et al. Phytate in foods and significance for humans: Food sources, intake, processing, bioavailability, protective role and analysis. Mol Nutr Food res 2009;53:S330-S375.

Source: Schlemmer U, et al. Phytate in foods and significance for humans: Food sources, intake, processing, bioavailability, protective role and analysis. Mol Nutr Food res 2009;53:S330-S375.

Source: Schlemmer U, et al. Phytate in foods and significance for humans: Food sources, intake, processing, bioavailability, protective role and analysis. Mol Nutr Food res 2009;53:S330-S375.

Source: Schlemmer U, et al. Phytate in foods and significance for humans: Food sources, intake, processing, bioavailability, protective role and analysis. Mol Nutr Food res 2009;53:S330-S375.

Conclusion: In comparison to other whole foods like vegetables and meat, foods that contain phytates can lead to malabsorption of certain key minerals. For example, calcium eaten with 100 calories of grain is likely to lead to a 7.6 mg rate of absorption, while calcium absorption eaten with 100 calories of vegetables is around 116 mg (Dr. Loren Cordian, The Paleo Answer). If you are generally healthy, eat a balanced diet, and consume grains, legumes, seeds, and nuts in moderation, phytic acid’s effect on mineral deficiencies should not be a major concern. The problem lies in consuming large amounts of phytates with little vegetable and meat consumption. My suggestion is to eat grains, legumes, seeds, and nuts in moderation if you are healthy and have no underlying deficiencies.

3. Tannins

These are a type of enzyme inhibitor that may impair the digestion of various nutrients. Since we need enzymes to properly digest foods and transport nutrients to our cells, molecules that inhibit enzymes from doing their job can cause bloating, diarrhea, constipation, and other digestive issues. In addition, their capability to bind and shrink enzymes is what causes the puckery and dry feeling in the mouth after consuming foods rich in tannins. During my research, I found that coffee, teas, red wine, grapes, pomegranates, berries, barley, nuts, chocolate, rhubarb, squash, and legumes all contain tannins. As with phytates, tannins have some possible benefits. They have been reported to reduce the mutagenicity of a number of mutagens and have some anti-carcinogenic activity. But from my research, there have been few studies on this effect on humans. Consuming foods rich in vitamin C can help neutralize the effects on tannin on iron absorption.

Conclusion: Consuming large quantities of tannins may result in negative health effects, specifically to the digestive tract; however in small quantities they may be beneficial to human health. My suggestion: don’t eat a quart of blueberries in one sitting!

4) Oxylates

Oxylate is an organic acid found in most plants (leafy greens, vegetables, fruits, cocoa, nuts and seeds). After consumption, oxalate can bind to minerals to form calcium oxalate and iron oxalate. For most people, these compounds are eliminated in the stool or urine, but for sensitive individuals high-oxalate diets can lead to an increased risk of kidney stones or other health problems. As with other antinutrients, the main concern is prohibiting mineral absorption. It is of particular concern, when minerals like calcium are eaten with fiber which can further prevents absorption.

Conclusion: Most healthy people can consume oxalate-rich foods without any problem, but those with poor gut health may need to limit their intake. Individuals with IBS (Irritable Bowel Syndrome) or IBD (Irritable Bowel Disease) have an increased risk for developing kidney stones. For those with digestive concerns, drink plenty of water and make sure to get enough calcium (well-sourced dairy, bok choy, broccoli, etc.), which will bind oxalate in the gut and reduce the amount the body absorbs.

5) Saponins

These compounds are similar to lectins. Saponins can create pores in the cell membrane. Some experts believe they may increase intestinal permeability, also known as “leaky gut”, which can lead to a range of health problems. Interestingly, saponins can stimulate an immune response from within our cells which can then up-regulate antibody production. This can be problematic as the body can launch an immune attack on undigested food particles that may enter in our blood stream. Saponins are found in a variety of plant sources (beans, peanuts, soy), nightshade vegetables, and seeds (quinoa and sesame). In addition, they are found in Yuccaschidigera (a commercial source) that is used in beverages to produce a foamy head, and extensively in lipstick and shampoo for is emulsion properties. Saponins are known for their ability to create foam in water and behave like a detergent. I do want to note that some saponins have shown to exhibit anti-inflammatory and immune-stimulation characteristics, as well as antimicrobial properties towards some fungi and bacteria. But once again, more studies need to be conducted in order to conclude any health benefits to humans. 

Conclusion: More research is needed to conclude whether saponins are truly harmful to the gut. For now, it is wise to play it safe and eat saponins in moderation or limit consumption due to their known ability to increase permeability in the small intestines.


You have probably noticed that most foods containing antinutrients also have positive health benefits and overall are healthier than eating processed foods (except modern, processed grain products like wheat, soy, and corn). So how can you best enjoy these foods if you are an average, healthy person? The answer: soaking, sprouting, and fermenting grains, beans, nuts, and seeds!

It is best to purchase sprouted or fermented grains (properly sprouted grains like quinoa or true sourdough bread). Some of my favorite bread brands are Angelic Bakehouse and Food for Life; although I personally don’t consume gluten often so I like the gluten-free versions. Fermentation and sprouting of grains can help break down the antinutrients. Soaking dry beans and other legumes overnight can improve their nutritional value and decrease phytate, lectins, tannins, and calcium oxalate. I still advise limiting your consumption though, as some types of legumes (kidney and soy especially) are still high in enzyme inhibitors even after soaking. Sprouting and soaking legumes and grains has been used in traditional preparation methods for thousands of years by various cultures. It is the recent mass production and processing of grains the last century that has stripped the nutritional value from typical grains and legumes. Evidence shows that by using these methods, grains’ nutrients are more bioavailable. If you choose to consume grains and legumes I suggest purchasing them organically and/or in bulk and sprouting them yourself to ensure the least amount of processing or chemical alteration. And as stated previously, make sure the remainder of your diet is varied with a lot of vegetables. And if you are susceptible to gut or digestive problems, limit or avoid grains and legumes all together in order to best reduce any negative digestive symptoms. To learn how to properly sprout beans check out the website Sprout People.

Overall, the benefit of eating antinutrients is overshadowed by their harmful properties, and proper preparation of grains and legumes can take an extreme amount of time. If a substance may be harmful to you when consumed, and there are no negative side effects of removing it, it may logically make sense to avoid it all together. I also want to make sure to note that organic white rice (jasmine and basmati) is white because the grain has been stripped of the bran, which removes almost all of the phytic acid, making white rice more digestible.  While white rice is still a grain, it is a safer option for those with digestive distress.