Woman holding out plant-based meal that naturally contains antinutrients

Antinutrients: Should You Avoid Them?

Everyone knows that eating healthy foods is the cornerstone of whole-body health. Foods like spinach, tomatoes, whole grains, and legumes are packed with the essential nutrients our bodies need to thrive. What’s more, a large body of research suggests that plant-based diets are associated with a lower risk of chronic diseases.

But sometimes piling your plate with more plant foods can impact digestion, resulting in uncomfortable bloating, gas or more serious symptoms, which can make anyone question how “healthy” these foods really are. It’s frustrating when a meal that seems to be the very embodiment of optimal human nutrition can make you wish you’d worn looser-fitting pants! Indeed, that hefty quinoa salad with tomatoes, black beans, seeds, nuts and mixed greens can be a real gut-buster—because these high-in-protein, high-fiber foods also have antinutrients, which are plant compounds that in some cases may interfere with digestion and nutrient absorption.

If you haven’t heard of antinutrients, you’re certainly not alone. But, if antinutrients are on your radar due to some Google sleuthing, you may be at a crossroads about whether you should cut out plant-based foods from your diet. There’s a lot of contradictory information about whether they are harmful (as the name suggests…after all, it’s “anti-nutrient”).

We’ll be the first to tell you that the answer is definitely not to eliminate plant foods from your diet. The foods that contain antinutrients happen to be among the most nutritious foods out there! That being said, knowing about antinutrients—and how to mitigate their effects on digestion—can help you enjoy these foods more comfortably. Here’s what you need to know about antinutrients and the food chemistry of our body’s absorption of plant compounds—plus, some hacks for digesting fruits, vegetables, nuts and other plant-based food sources.

What are antinutrients?

Antinutrients are bioactive plant compounds that protect plants from predatory insects and infections—so that your favorite fruit, vegetable, legume or other plant-based food can survive and thrive… and, ultimately, make it to your plate intact. Unfortunately, that “protective armor” which fends off threats and pests may be a little rough going down. Antinutrients may also mean that you don’t absorb all the goodness from your food.

How do antinutrients impact digestion?

Antinutrients do not always impact digestion—everybody’s biology is a bit different. For those who do struggle a bit with plant-based foods, there are two main ways that antinutrients can interfere with digestion:

1. You might feel uncomfortable after you eat.

Digestion starts the moment we take a bite (or smell, see or think about food) thanks to your digestive enzymes. These specialized proteins facilitate the breakdown and future absorption of carbs, fats and proteins from the foods you eat. Certain antinutrients may inhibit these digestive enzymes from doing their job. For example, some antinutrients interfere with alpha-amylase, the enzyme that breaks down carbs. And, antinutrients can act as trypsin inhibitors and protease inhibitors, meaning that they might get in the way with your body’s ability to digest proteins.

2. You might not absorb all the health benefits from your diet.

Antinutrients also can affect the absorption of nutrients when not prepared correctly or when you eat them in excess. And they may impact whether you get the benefits from other foods on your plate. Antinutrient compounds can bind to or otherwise inhibit the absorption of vitamins like B12 and minerals like zinc, copper, and iron, reducing their availability to the body. For example, when you eat a chickpea and beetroot salad—which contains the antinutrients lectins, oxalates and phytic acid (phytates)—your body may not get all the fats, protein, fiber, healthy carbs, vitamins, minerals and antioxidants this nutritious dish contains.

Cooking foods and other processing techniques can mitigate both of these concerns, however. More on that in a bit!

6 common antinutrients

The six plant compounds most commonly known for containing anti-nutritional factors are saponins, goitrogens, lectins, oxalates, tannins, and phytates (phytic acid). You’ll find these in food staples like whole grains, legumes, cereals, nuts, seeds, fruits and vegetables. Here’s more about each antinutrient and where you can find them (you’ll note that some foods contain more than one kind).

  1. Saponins—These antinutrients are commonly found in quinoa and starchy grains like millet and have a bitter taste. You’re correct if you think the word “saponins” sound very much like the word “soap.” The name derives from its soap-like properties. And you’ve probably seen them in action already; the foam that forms when you soak and wash quinoa is all thanks to saponins!
  2. Goitrogens—Some foods like cabbage, Brussels sprouts and millet contain goitrogenic compounds that can also interfere with adequate iodine absorption, which could impact thyroid health. However, the goitrogen concentration in these foods is very low, and cooking them significantly lowers their impact on digestion. Research shows that a typical serving of raw cruciferous vegetables doesn’t affect iodine absorption or your thyroid.
  3. Lectins—Found in a wide variety of foods—ranging from nightshade vegetables like tomatoes to whole grains, quinoa and legumes—lectins are considered antinutrients because they can harm the integrity of intestinal cells and proper activity of the immune system, as well as interfere with adequate nutrient absorption. However, the lectin content in raw fruits and vegetables isn’t significant enough to be a problem; the real concern comes from improperly cooked legumes or grains. Instead of avoiding lectins-containing legumes and grains, you can reduce any negative impact with the right cooking techniques.
  4. Oxalates (oxalic acid)—You’ll find these in high quantities in some green leafy vegetables like spinach and Swiss chard, as well as soybeans and other legumes, sesame seeds and millet. A high dietary intake of oxalates can reduce your absorption of some minerals. More troublingly, because oxalates can form calcium oxalates, they may contribute to kidney stones. And here’s where it can get tricky. There’s some research that shows there’s no direct correlation between high dietary oxalate intake (like eating a lot of spinach) and kidney stones; other studies show a low-oxalate diet is recommended for people who are prone to kidney stones. So, what to do? Of course, cutting out leafy greens and vegetables from your diet isn’t ideal. Your doctor or a nutritionist can recommend a tailored diet that lowers oxalate consumption while still keeping you well-nourished.
  5. Tannins—Maybe you’ve heard this term in reference to wines? Tannins are polyphenols found in foods like fruits (grapes, of course!), cacao, tea and coffee. They are considered antinutrients because they can act as protease inhibitors, potentially reducing protein digestibility and inhibiting adequate amino acid absorption. Tannins can also reduce iron uptake. But there’s plenty of evidence that suggests that a plant-based diet rich in polyphenols exceeds any potential negative effects of tannins.
  6. Phytates—These antinutrients inhibit how well your body absorbs nutrients like iron and zinc. Lupini beans and other legumes have a high phytate content. Their effects tend to be more of a concern in developing countries where beans and other phytate-rich foods are consumed in high amounts and make up a large part of their diet. But washing and soaking these foods before cooking them can often help lessen phytate’s effects.

What foods are high in antinutrients?

Here’s a list of foods that have a high concentration of antinutrients and the potential negative effects they can have. Pro tip: While some of these drawbacks sound severe, note that with proper food preparation, most of these healthy foods offer far more benefits than they do risks.

Antinutrients Foods Possible effects
Goitrogens Cruciferous vegetables like kale, broccoli, Brussels sprouts, cabbage, millet, cassava May reduce iodine absorption

Legumes, cereal grains, seeds, nuts, fruits, vegetables

Digestive disruption, may cause inflammation
Phytate (phytic acid) Legumes, cereal grains, quinoa, nuts, seeds

May inhibit proper absorption of minerals like zinc and calcium

Oxalates Spinach, Swiss chard, sorrel, beet greens, beetroot, rhubarb, nuts, legumes, whole grains, sweet potatoes, potatoes

May interfere with calcium absorption; may increase kidney stone formation (made up of calcium oxalate)

Saponins Quinoa, legumes, spinach, oats, whole grains, licorice root May interfere with nutrient absorption
Tannins Cacao, tea, coffee, legumes, grapes, berries, nuts, beans, whole grains May decrease iron absorption and storage

Why do foods have antinutrients?

If these foods are healthy for us, why do they have active compounds that can impact human health? Well, they’re there to protect the plant, not us; for example, research has identified over 500 lectins in plants that protect them from insects, molds, fungi and disease.

Are there any benefits to antinutrients?

Yes! Despite their name and possible negative effects, emerging research shows that the plant compounds we call antinutrients can have therapeutic benefits for various conditions. For example, lectins may help prevent harmful cellular overgrowth. Meanwhile, polyphenols like tannins can have antioxidant properties and help protect cells from oxidative stress; they’ve been shown to promote a healthy inflammatory response, which is essential for overall health and whole-body comfort. A polyphenol-rich diet has also been shown to help reduce the risk of cognitive decline and dementia.

And while it’s true that phytates (or phytic acid) may negatively affect digestion and mineral absorption, their antioxidant benefits far exceed these drawbacks. Phytates help protect your cells from oxidative stress and have been shown to support healthy inflammation and immunity.

So, don’t judge antinutrients by their (unfortunate) name—with the right hacks, you can eat these plant compounds to your advantage!

Is gluten an antinutrient?

Not for most people. Gluten is a protein found in foods like rye, barley and grains. As a protein, your body has enzymes that can digest some of it but not entirely. Most healthy people can handle undigested gluten when it enters the small intestine. However, any and all gluten can trigger unpleasant symptoms in people who are gluten intolerant or have celiac disease. That’s why following a gluten-free diet can be more beneficial for their overall health. If you experience health conditions like gluten sensitivity or celiac disease, avoiding gluten-containing foods is a wise choice for your well-being.

Should everyone avoid antinutrients?

No! Some plant sources contain antinutrients, but their nutritional value is essential to your well-being, so by all means, eat up! Let’s not forget that many foods that have antinutrients are rich sources of flavonoids and other famously beneficial plant compounds. You shouldn’t deprive your body from the colorful health benefits plant foods bring to your diet. After all, foods like Swiss chard, spinach, brussels sprouts, broccoli, beets, beans, chickpeas, whole grains, nuts and seeds offer irreplaceable nutritional value to your body and keep you functioning optimally. A number of antinutrients offer health benefits like helping reduce cholesterol levels, balancing blood sugar levels, conferring antioxidant protection and more.

There are exceptions, of course. If you have a thyroid condition (or are iodine deficient), avoiding large amounts of raw cruciferous vegetables in a single meal, which contain goitrogens that might interfere with iodine uptake, is a smart way to find balance. And of course, you don’t want to eat any food in excess, even broccoli and quinoa! But, in general, the average healthy person would benefit more from adding more plant-based sources to their diet than avoiding them, as much as you may hate Brussels sprouts and broccoli.

4 ways to avoid the ill effects of antinutrients

If you ever thought cooking legumes, quinoa and other plant foods was time-consuming because your grandmother always soaked or washed them before cooking them, you’re not alone. Many of us have questioned the traditional cooking wisdom of generations past—but it turns out they were right.

Those extra steps in prepping and cooking these foods can help minimize any potential negative effects antinutrients might have, so you can enjoy the health-promoting benefits of plant-based meals! Here’re four ways to do so:

  1. Soaking—The next time you’re cooking grains, quinoa or lentils, soak them in water for at least 15 minutes (you can also leave it overnight). It can significantly reduce the impact antinutrients can have on your digestive health. Pro tip: Add a teaspoon of apple cider vinegar. This creates an acidic environment that activates the digestive enzyme phytase, which breaks down phytic acid. This, in turn, can help improve the digestibility of these foods.
  2. Boiling—When you boil foods like beans, it changes the molecular conformation of compounds such as lectins or goitrogens, which helps minimize their possible negative effects.
  3. “Autoclaving”—Ok! This one sounds like a made-up step, but the word just means to heat something under high pressure to sterilize it. For example, canned legumes are sterilized in airtight containers, reducing their antinutrient content significantly. 
  4. Fermentation or sprouting—These processing methods can significantly reduce the phytate content in foods like whole grains, legumes, seeds and nuts, improving their digestibility.

What do I do if antinutrients upset my stomach?

In addition to the food prep tips above, eating foods in moderation and listening to your body are an essential part of enjoying every meal. Pay close attention to how you feel after you eat and take note when specific plant-based foods cause digestive discomfort. For example, if you’re a tomato fan and enjoy starting your day with a cherry tomato and avocado combo, watch out for symptoms like uncomfortable bloating. It could be a sign that you’re overeating tomatoes. In that case, you may want to eat tomatoes sporadically throughout the month instead of religiously every morning. You can also peel the skin of tomatoes and remove the seeds to help reduce their effects.

Adding digestive enzymes to your routine is another good way to keep the upper hand on those pesky antinutrients. And don’t forget that lab tests can help you uncover the real reason your food is making you feel sick. If you notice you don’t feel like your normal self after eating certain foods, you may want to do a food sensitivity test to see if your body has developed an immune response to any foods.

About the Author: Jessica Monge has a bachelor's degree in biological sciences & neuroscience and a master's degree in comparative studies and related languages from Florida Atlantic University. She worked as a tutor, freelance writer and editor before joining Life Extension, where she is currently a Digital Content Writer.