Sharing is Caring!
Legumes provide low nutritional value

What Are Antinutrients? – A Science-Based Review

This post may contain affiliate links. Please read my disclosure for more info.

Antinutrients are a controversial topic among the healthy-eating community, and particularly in the Paleo world. But what exactly are antinutrients? Why are they such a controversial topic? And are they bad for your health?

In this article, we’ll explore the science behind those so-called enzyme inhibitors, and I’ll provide clear answers to the most common questions people have. I’ll also identify foods that have high amounts of antinutrients, and highlight techniques for reducing the levels of those potentially-toxic compounds in the foods you eat.

What are Antinutrients?

Antinutrients are chemical compounds that you can find in many animal and plant-based foods, including ones that are otherwise considered healthy and Paleo-friendly.

In nature, plants use antinutrients to protect themselves from predators. In other words, these substances prevent plants from being eaten by animals.

Unlike nutrients that provide nourishment, antinutrients block the absorption of individual proteins, vitamins and minerals, and they can punch holes in your intestinal walls. That leads to increased intestinal permeability, which is a fancy term for a leaky gut. The consumption of antinutrients can also lead to mineral deficiencies — particularly if you have a diet low in wholesome foods.

We already know that increased intestinal permeability plays a role in certain gastrointestinal conditions such as celiac disease, Crohn’s disease, and irritable bowel syndrome. The biggest question is whether or not a leaky gut may cause problems elsewhere in the body. Some studies show that leaky gut may be associated with other autoimmune diseases (lupus, type 1 diabetes, multiple sclerosis), chronic fatigue syndrome, fibromyalgia, arthritis, allergies, asthma, acne, obesity, and even mental illness. However, we do not yet have clinical studies in humans showing such a cause and effect.

Marcelo Campos, MD – Harvard Health

While the studies referenced by Dr. Campos correlated those findings to Type 1 diabetes, other diseases — such as Crohn’s disease or coeliac disease — followed a similar pattern.

Another study, conducted by researchers at the University of Alberta, concluded that “in several autoimmune conditions it appears that increased permeability is a constant and early feature of the disease process. Furthermore, it is becoming increasingly apparent that in some conditions increased permeability is critical to the development of disease as if it is abrogated the disease does not develop.”

My Recommendation

The Paleo Diet
What did your ancestors eat?

When confronted with cases of inconclusive or conflicting scientific evidence, I always apply the evolutionary framework. That means I stick to foods that our bodies are genetically set up to thrive on. In other words, I follow the diet our Paleolithic ancestors adhered to for millions of years (based on what we know about their dietary habits).

As a result, I avoid grains because we know with a high degree of confidence that humans didn’t eat them until 10,000 to 13,000 years ago. Regarding legumes, there is evidence that early humans might have eaten them before the onset of modern agriculture. However, since legumes don’t offer any nutritional advantage over healthier alternatives, I generally avoid them as well.

To better understand how I have come to these conclusions, continue reading. Let’s start with a list of the most popular antinutrients.

Some leafy-green vegetables have Oxalates
Some leafy green vegetables have Oxalates

List of Common Antinutrients

Here are eight of the most problematic antinutrients:

Lectins

antinutrients - pea lectin protein
Pea lectin protein

You’ve probably heard about lectins. Eating lectin-free foods is becoming a “thing,” just like eating gluten-free.

The problem with lectins is that they can cause a leaky gut (also known as intestinal permeability). When you eat foods containing too many of these proteins, they bind to cells in your gut wall. This punctures your gut wall and creates holes, through which your gut’s contents can leak — unfiltered — into your bloodstream (enabling inflammatory pathways).

Lectins are naturally-occurring proteins found in a variety of foods. They occur in higher concentrations in legumes and grains. Lectins are most commonly found in the section of a seed that becomes a leaf after sprouting occurs.

Here’s why lectins are high up on the antinutrients list: lectins recognize and bind to carbohydrates and glycoconjugates. After binding, the lectins pass through the body and enter the bloodstream without ever succumbing to digestion.

In certain foods, lectins can cause food poisoning. For example, you should never eat raw red kidney beans because they contain up to 70,000 lectin units (versus up to 400 lectin units in fully-cooked beans).

Glucosinolates

Glucosinolates are compounds found in cruciferous vegetables like Brussels sprouts and cabbage. Glucosinolates prevent the body from absorbing iodine, flavonoids, and minerals such as iron and zinc. Studies show that a higher intake of glucosinolates is associated with a greater risk of Type 2 diabetes.

Oxalates

Oxalates are found in plant-based foods like spinach, beans, black pepper, and beets. They bind to calcium, preventing the body from absorbing this vital nutrient.

If your muscles are not absorbing calcium, you will experience muscle pain. Also, unused calcium can accumulate in the kidney and cause kidney stones.

Phytates or Phytic Acid

Phytates are found in the hulls of whole grains, seeds, and legumes such as soybeans and peanuts. Phytates also bind to essential dietary minerals, including calcium, magnesium, iron, copper and zinc. This makes them unavailable for the body to use.

Barley is a source of gluten
Barley is a source of gluten

Gluten

Most health foodies are aware of the adverse effects of this antinutrient. Gluten is found primarily in wheat, barley, and rye. Based on statistics, scientists estimate that up to 7% of the domestic population is sensitive to gluten (non-celiac gluten sensitivity).

According to Dr. Fasano, gluten sensitivity potentially affects far more people than celiac disease. He estimates about 6% to 7% of the U.S. population may be gluten-sensitive, meaning some 20 million people in the United States alone could have the condition.

That’s much more than the 1% of people who are thought to suffer from celiac disease.

Saponins

Saponins have soap-like properties
Saponins have soap-like properties

Saponins are mainly found in legume plants. The name saponin comes from this antinutrient’s ability to form soap-like foams in solution. Like lectins, saponins can bind to the gut and can increase intestinal permeability.

Tannins

You may have heard of tannins as the element that gives wine its dry taste.

Tannins are naturally-occurring polyphenols. You can find them in various plants, seeds, bark, wood, leaves and fruit skins. Tannins are antinutrients because they inhibit the absorption of iron.

Trypsin Inhibitors

Trypsin inhibitors are proteins that block trypsin activity. Trypsin is one of the digestive enzymes involved in the digestion and absorption of protein.

Trypsin inhibitors are antinutrients because they prevent our bodies from digesting and beneficially using protein.

Other Antinutrients

Beyond the most important enzyme inhibitors mentioned above, here are a few more antinutrients (and foods containing them):

  • Uric acid: Meat, organs, eggs, dairy, legumes and some vegetables
  • Oligosaccharides: Legumes
  • Avidin: Egg white
  • Cyanide: Beans and fruit pits
  • Goitrogens: Soy, peanuts and cruciferous vegetables
  • Alpha-amylase inhibitors: Grains, legumes, nut skins and stevia leaves
  • Allicin and mustard oil: Onions, shallots, leeks, chives, scallions and garlic
  • Salicylates: Berries, dried fruits, herbs and spices
  • Calcitriol, solanine, nicotine: Green potatoes, eggplant, peppers, tomatoes and goji berries

Top Foods Containing Antinutrients

The following are the top four food categories that contain high amounts of antinutrients:

Legumes

Many raw beans are toxic due to high antinutrient concentrations
Many raw beans are toxic, due to high antinutrient concentrations

Legumes — including cowpeas, peas, kidney bean seeds and peanuts — contain antinutrients such as tannins, phytic acid and trypsin inhibitors.

For a long time, I thought that our Paleolithic ancestors didn’t consume legumes because they didn’t know how to process them. I was wrong. Scientists have found neanderthals with starches between their teeth that resembled carbohydrates from cooked legumes. If you think about it, that makes sense: how could they have started cultivating legumes and grains without having discovered them beforehand?

However, while early humans might have been exposed to grains and legumes, those items weren’t a staple of their diets (like they are for us today). Plus, our genetically- and lab-modified versions of these foods have (genetically) little in common with the ones humans might have eaten over 10,000 years ago.

More importantly, legumes have low nutritional value compared to healthier alternatives. And since I have no desire to spend a lot of time correctly processing them (see below), I see no reason to make them part of my diet. In business terms, I’d say that grains and legumes have a weak value proposition.

Grains

Cereals have a low nutritional density
Cereals have a low nutritional density

The hulls of whole grains contain the antinutrients phytate and saponins. Also, certain grains — wheat, barley and rye — contain the antinutrient gluten.

From a nutritional perspective, grains are even worse than legumes. In other words, grains are on the bottom of the list when it comes to nutrient density. You don’t need them, and no processing method in the world removes all the antinutrients (such as gluten) they contain.

Because of their low nutritional value and high antinutrient content, I generally recommend cutting grains out of your diet entirely.

Vegetables

Raw cruciferous vegetables such as kale, radishes, cauliflower and broccoli, as well as leafy greens such as spinach and parsley, contain the antinutrient oxalic acid. Other veggies also have oxalates, but in lesser amounts.

Nuts and Seeds

Nuts and seeds have antinutrients
Nuts and seeds have antinutrients

Most nuts (in particular, the hulls of their seeds) contain phytate. That kind of throws a wrench into the hypothesis that nuts are healthy, and seeds (such as chia seeds) are superfoods, doesn’t it?

The good news is that you can easily remove or reduce the amount of antinutrients in healthy food.

Eliminating Antinutrients from Food

Some methods of preparing food can (partially) remove antinutrients. Examples include heat treatments such as boiling, roasting, microwave cooking and autoclaving. Others include processing methods such as dehulling, soaking and fermentation.

If you don’t take the time to remove antinutrients from certain foods, you may experience side effects such as nausea, vomiting and diarrhea, as well as long-term health issues such as inflammation.

Sprouting

Sprouting can remove certain antinutrients
Sprouting can remove certain antinutrients

Legumes are the most abundant source of the antinutrient lectin. However, one way to get rid of lectins is through sprouting.

Lectins are found in the seed coat. During sprouting or germination, the seed coat is metabolized, thus eliminating the lectins.

Soaking and Boiling

Soaking and boiling can remove some antinutrients
Soaking and boiling can remove some antinutrients

Ever wonder why your mother passed down the age-old tradition of soaking and rinsing beans repeatedly before boiling? Studies show that the tannins in legumes are found mainly in their seed coats. Lectins are also found in the seed coats. In fact, there’s a particularly problematic lectin (agglutinin) that is found in soybeans (and thus, in soy products like soy protein isolate).

The seed coats that contain tannins and lectins are soluble in water. In essence, if you soak or boil legumes (like beans) for a sufficient period of time, the antinutrients will leach into the water, decreasing (but not eliminating) the concentration of antinutrients inside the seeds.

Legumes also contain phytic acid, which is another antinutrient. When you expose legumes to heat, phytic acid combines with the calcium and magnesium inside the seeds to form insoluble calcium and magnesium phytates. Humans cannot digest these insoluble compounds (3). This is one of the reasons why I recommend staying away from raw peanuts.

Another type of antinutrients in legumes that are affected by heat are trypsin inhibitors. These are protein molecules, and any application of heat can cause a breakdown (denaturation) of protein structures (thus impacting protein digestibility). In fact, the longer you heat legumes, the more the trypsin inhibitors are denatured. One study showed that cooking lima beans for one hour resulted in a complete elimination of trypsin inhibitors.

Dehulling

Next, let’s take a look at whole grains and seeds. I already mentioned that phytic acid is found in the hulls of whole grains and seeds. Therefore, it would make sense that dehulling would decrease the antinutrients in those foods.

That’s also why white rice is healthier than whole rice; it doesn’t have a hull. So much for whole grains always being healthier! The other reason why rice is generally less problematic is that it contains only ~1% of protein as opposed to >10% in wheat. Remember, it’s the proteins in grains that cause issues (such as celiac disease).

Fermentation

Fermenting food can remove some antinutrients
Fermenting food can remove some antinutrients

In ancient times, humans fermented grains to make them easier to consume. The earliest archeological evidence of fermentation is wheat-and-barley-based alcohol that dates back 13,000 years. Archeologists discovered these fermented grains inside stone mortars in a pre-historic cave in Israel.

Fermentation breaks food down with the help of beneficial bacteria. These bacteria can digest and convert many of the harmful antinutrients.

However, you should note that fermentation does not remove all antinutrients. Some stubborn lectins (especially those found in beans) are not destroyed by fermentation.

How to Resolve the Antinutrient Controversy?

How to resolve challenging situations

I have been following a Paleolithic lifestyle for over three years, and I knew that grains and legumes weren’t permitted while on the Paleo diet. But leafy-green vegetables and nuts (such as almonds) are favorites in this ancient diet.

So, is there a difference between antinutrients in legumes/grains and kale/spinach/peppers? Maybe. Let’s look at one example.

Oxalic Acid and Calcium

As we learned above, the oxalic acid in leafy greens can prevent the body from absorbing calcium. That paints some of these so-called superfoods in a bad light, doesn’t it?

Red meat can improve calcium absorption
Red meat can improve calcium absorption

You probably have also heard that red meat is bad for you. However, eating animal protein has been associated by scientists with improved calcium absorption.

On a side note, consuming red meat isn’t bad (unless it’s processed). But that’s the topic of another article.

The takeaway here is that every food has varying degrees of pros and cons. However, evolution has shaped our bodies so that we can eat and metabolize certain foods better than others. For instance, humans are perfectly capable of thriving on pastured meat, animal fats, wild-caught seafood, seasonal vegetables and fruits.

Evidently, we are not adapted (or are only partially adapted) to consuming grains, dairy and modern legumes. It’s as simple as that.

However, when in doubt — and when there is conflicting scientific evidence — I always apply the evolutionary framework. In other words, I do what we have learned our ancestors did successfully for millions of years.

The point is to pick wholesome sources of food that provide the highest levels of micronutrient density, even if they come with antinutrients. Grains and legumes have incredibly low nutrient density compared to healthier alternatives such as pastured meat, poultry, and vegetables. That’s one of the reasons why I exclude them from my diet (and why you should too).

How to Deal With Conflicting Information

If you’re just starting out in your journey to healthy eating, the available information about antinutrients may prove confusing. Solid research on associated conditions, such as leaky gut syndrome, is only about a decade old. While that might seem like a long time, the reality is that it takes up to 20 years for scientific evidence to make it into medical school and practice.

So don’t be surprised if your primary care physician still hasn’t heard the term “leaky gut” and thinks diet has nothing to do with chronic disease. Some people, including medical professionals, even claim that antinutrients are a myth and you shouldn’t worry about them.

USDA MyPlate
USDA MyPlate

Case in point: the American Dietary Guidelines still recommend filling your plate with whole grains, a significant source of antinutrients and empty calories.

However, after having seen the evidence and heard the arguments from both sides of the aisle, I conclude that it’s difficult for the average consumer to fully understand under what circumstances the antinutrients in individual foods can cause harm.

The standard American diet is evidently not working, considering the recent explosion of auto-immune and metabolic diseases — all of which have a common root: systematic inflammation, which is influenced by what we eat. So stick with the diet and foods that have worked well for humans and our ancestors for 2.5 million years.

Hint: It’s pretty much the exact opposite of what the US government recommends you to eat!

Frequently Asked Questions

Below is a list of questions I hear often. I already answered most of them in some shape or form throughout this article, but since they are so prevalent (and so important), I’m spelling them out again.

Raw food should be part of a healthy diet
Raw food should be part of a healthy diet

Are Antinutrients as Unhealthy as Some Say?

As I’ve discussed already, antinutrients prevent the body from absorbing the essential nutrients it needs. Plus, in sufficient concentrations, they can make you seriously sick (or even kill you). Therefore, antinutrients by definition aren’t good for you.

However, you will find varying degrees of antinutrients in all types of food. And here’s the catch: you cannot avoid eating food. The truth is that the pros of healthy foods that contain antinutrients far outweigh the cons. What we can do is control what foods we choose to eat (and how we process these foods).

I always consider the evolutionary framework when deciding whether the benefits of eating a particular type of food outweigh the risks.

Take legumes, for example. Most people claim that legumes are beans, but the definition is broader than that. These plants are found in a vast array of ecosystems in every place except Antarctica. Ancient hunter-gatherers found legumes while hunting. Then, between 10,000 and 20,000 years ago (Epipaleolithic and Neolithic), a group of humans in southwest Asia started cultivating lentils, peas, bitter vetch and wild chickpeas.

Lentils, peas, and bitter vetch were first cultivated in the Fertile Crescent, while wild chickpeas were first cultivated in southeastern Turkey. Our ancient ancestors thought it was a good idea to grow them in one location versus finding them randomly in the wild. This idea is what developed into modern-day agriculture.

People who follow the Paleo diet tend to avoid legumes because they have higher concentrations of antinutrients. However, the Paleo diet is modeled from foods our ancestors likely ate during the Paleolithic era.

So should we exclude legumes? Here’s what’s interesting. Researchers have reported evidence of legumes recovered from the teeth of Neanderthal skeletons. This means that legumes were part of the Paleolithic-era diet (at least to some extent).

However, it’s essential for us to consider that raw legumes are toxic without proper preparation methods such as soaking, boiling and fermentation.

Grams of protein per 100kcal
Grams of protein per 100 kcal

Plus, the nutritional value in legumes — compared to healthier alternatives such as meat, fish and other animal foods — is incredibly low. Beans, peas, and other legumes actually contain 66% less protein than either lean chicken or turkey, and 61% less protein than lean beef, pork, and seafood. This is another indication that it may be beneficial to stay away from them.

To be on the safe side, you should only eat legumes if they have been appropriately prepared with methods that remove antinutrients.

People in China Eat a Lot of Foods That Contain Antinutrients, And They Don’t Get Sick

If you look at the top ten causes of death in China, you’ll see that nine out of ten Chinese dies of a metabolic disease, such as cardiovascular disease or cancer. Even worse, the rates of metabolic disorders in China have gone up significantly between 2007 – 2017. The number of deaths stemming from Hypertensive heart disease, for example, have gone up by almost 100%.

Metabolic diseases aren’t an issue of Americans, it’s a global phenomenon that goes hand-in-hand of how humans how changed their dietary habits.

How About People in India? Are They Affected By Metabolic Diseases Too?

Unfortunately, yes! Six out of the top ten causes of death in India are metabolic diseases, and those rates are dramatically increasing. Coincidentally, infectious diseases are on the decline.

Does Flaxseed Have Phytic Acid?

Just like other seeds, flaxseed has phytic acid. To remove these antinutrients, soak them for at least six hours.

Do Cashews Contain Lectins?

Nuts, including almonds and cashews, contain very high levels of lectins. Unfortunately, unlike cooking legumes, cooking nuts will not eliminate lectins.

Do Bananas Have Phytic Acid?

The hulls of seeds contain phytic acid. Since bananas are not a seed or grain, they do not contain any detectable phytic acid.

Does Quinoa Cause Leaky Gut?

Quinoa is considered a superfood staple. However, quinoa contains certain antinutrients, including saponins, phytic acid, and oxalates.

The problematic thing about quinoa is that it’s whole and unprocessed, which makes it difficult for many people to digest. Quinoa contains antinutrients known as saponins. Like lectins, saponins can bind to the gut, resulting in holes that cause the leaky gut syndrome. If you have to have grains, I would stick with white rice over quinoa, if I were you.

Do Plant-Based Diets Increase my Exposure to Antinutrients?

Probably, because plants are a significant source of antinutrients. However, while I don’t recommend a strict plant-based diet for nutritional reasons, seasonal fruits and vegetables should still make up a large portion of every single meal.

Should I Supplement with Vitamins and Minerals?

We have learned that some antinutrients prevent your body from absorbing individual minerals. However, we have also learned that nutrients in other foods and proper food preparation can significantly reduce the risk.

In other words, if you have a healthy dietary lifestyle, you might not need supplements. To learn more about that topic, check out this article I recently published.

Should I Stay Away From Raw Food

I wouldn’t go so far as removing all raw food from your diet, except for foods that you know are toxic because of their antinutrient concentrations. For example, fresh beans have high amounts of plant lectins; thus, you shouldn’t eat them raw.

Also, keep in mind that any process you apply to reduce the number of antinutrients might destroy other nutrients as well. Many vitamins are water-soluble or heat-sensitive. So keep that in mind!

Can Antinutrients Cause Heart Disease?

Besides the immediate effects of antinutrients on your body and digestive tract (i.e., digestive problems), continuous exposure to those enzyme inhibitors can lead to systematic inflammation, which is the leading cause of all kinds of chronic diseases, including cardiovascular problems.

Do (Sweet) Potatoes Contain Antinutrients?

Both regular and sweet potatoes contain numerous antinutrients, including patatins, lectins, salicylates, and protease inhibitors.

That’s one of the reasons why raw green potatoes are toxic, and why you need to cook ripe potatoes before enjoying them.

How Can I Remove Gluten From Food?

Unfortunately, you can’t. The only way to avoid the consequences of gluten sensitivity is to have a gluten-free diet.

Do Fruits Have Antinutrients?

Yes, certain fruits have antinutrients called vaso-active amines and salicylate.

Legumes provide low nutritional value
Legumes provide low nutritional value

Conclusion

Based on scientific evidence, antinutrients are a real thing and can cause health issues. However, you should note that the benefits of eating certain healthy foods far outweigh the disadvantages of the antinutrients found in them.

Some foods containing antinutrients are part of our evolutionary framework. If necessary, take the time to remove the antinutrients by sprouting, soaking, boiling, dehulling and fermenting these foods.

For instance, keep eating your kale and spinach. But instead of eating it raw, consider steaming or sautéing it first. Unfortunately, many of the methods that destroy antinutrients, also destroy nutrients, such as water-soluble or heat-sensitive vitamins. Therefore, you have to find a balance.

I recommend removing foods that contain large amounts of antinutrients, with comparatively low numbers of nutrients (e.g., grains and legumes), from your diet.

About the Author Michael Kummer

I was born and raised in Austria. I speak German, English, and Spanish. Since moving to the U.S., I have lived and worked in the greater Atlanta area. In my twenties, I was a professional 100m sprinter. These days I do mostly CrossFit. I'm a technologist and Apple fan. I love science and don't believe anything unless there is proof. I follow a Ketogenic Paleo diet and intermittently fast every day. I'm married and have two trilingual kids. My goal with this blog is to share what I learn so that you can spend time on something else. Check out my latest Diet, Fitness, and Technology articles.

follow me on:
>