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What Are Anti-Nutrients and Are They Harmful?


Eating a nutrient-dense diet is one of the best ways that you can take care of your body.

However, even some of the healthiest foods out there may contain compounds called “anti-nutrients” that inhibit nutrient absorption.

If your body isn’t able to absorb and assimilate those micronutrients, is it even worth eating healthy food?

Anti-nutrients get a bad reputation, but they may not be as harmful as they’re made out to be.

What Are Anti-Nutrients?

Antinutrients are compounds found naturally in plant foods that serve as protection to the plants against bacteria and predators.

These compounds are termed “anti-nutrients” because they tend to block the natural absorption and assimilation of nutrients in your body.

While the term anti-nutrient may sound off-putting, these compounds actually play both sides of the field and may provide your body with some potential health benefits.

Some of the most prominent anti-nutrients in your food include:

#1 Glucosinolates

Glucosinolates are found widely in the cruciferous vegetable family. Vegetables like cabbage, kale, broccoli, and brussels sprouts are rich sources of these anti-nutrients.

People with thyroid disorders are often advised to be wary of cruciferous vegetables due to glucosinolates affinity for binding with iodine[*].

Iodine is a crucial mineral involved in the health of your thyroid. Together with the amino acid tyrosine, your body creates thyroid hormone from iodine — therefore a deficiency would directly affect thyroid function.

While those with a thyroid hormone deficiency or thyroid dysfunction are the most at risk when it comes to glucosinolates, anyone with thyroid health in mind should be aware of them.

However, on the other hand, glucosinolates are also known to provide some significant health benefits. One well-studied benefit of these compounds come from a product of its breakdown called isothiocyanate.

In your small intestine, an enzyme called myrosinase breaks down glucosinolates and produces isothiocyanate. This same process can also occur in your large intestine by bacterial myrosinase.

Isothiocyanate plays a role in phase 2 detoxification in your liver — supporting the removal of wastes out of your body.

It’s also known to be cancer-protective, inhibiting cancer cell growth and stimulating cell death[*].

Another key role that isothiocyanate plays is in its transformation to glutathione — a potent antioxidant. As an antioxidant, glutathione has a number of roles in both combating oxidative stress and calming inflammation in your body[*].

#2 Lectins

Lectins can be found in a wide variety of plant foods, especially nuts, grains, and legumes.

While most studies have been done on animals, research shows that consuming high levels of lectins can produce potentially harmful effects in both your digestive tract and within your body system.

When you consume lectins, they don’t get broken down by your digestive juices or enzymes. Instead, they survive the digestive process and may wreak havoc on your intestinal lining. Lectins are known for their binding properties, and they may end up binding to the cells that line your digestive tract.

When this happens, these anti-nutrients may create a toxic effect on your gut which results in a harmful local and systemic reactions in your body.

Locally, they can inhibit the proper turnover of the cells in your gut lining, damage your gut membranes, and interfere with nutrient digestion and absorption. Additionally, they can create shifts in your microbiome that result in issues with both immunity and digestion.

Systemically, lectins can disrupt proper lipid, carbohydrate, and protein metabolism. They can cause damage to vital internal organs, and alter hormone and immune processes[*].

With all of that being said, there are some potential benefits to lectins as well. For instance, in nettle leaves, there is a type of lectin that exhibits antifungal properties. While this lectin is meant to protect the plant from fungal growth, its benefits may transfer to human health[*].

Other research also supports certain types of lectins for their antimicrobial and antioxidant activities[*].

#3 Oxalates

Oxalates, also referred to as oxalic acid, can be found in a wide range of foods. Specific fruits and vegetables, as well as nuts, seeds, and grains, carry varying amounts of oxalates[*].

The number one issue associated with oxalate intake is the production of calcium-oxalate kidney stones. This is due to oxalates affinity for binding calcium.

When oxalates are consumed, they typically bind to minerals in your digestive tract and then are eliminated along with the minerals they’ve bound. While this causes a decrease in mineral absorption, in most cases getting the oxalates out is a more important process than keeping minerals in[*].

In some cases, however, oxalates can build up in your system, and eventually lead to kidney stones. This can be due to issues with your digestion, imbalanced microbiota, or not having enough minerals to bind the oxalates.

As a result, your body passes the oxalates through your kidneys to be excreted, increasing the risk for stone formation[*].

Unlike the other anti-nutrients, oxalates don’t seem to offer many health benefits themselves.

However, they’re often found in a variety of health-promoting foods like fruits and vegetables. Due to the high nutrient quality of oxalate-rich foods, it may be worthwhile to learn how to reduce the oxalate content of foods instead of avoiding the foods altogether.

It should also be noted that the health of your digestive tract has a lot to do with whether or not oxalates will be harmful to your health or not[*].

#4 Phytates

Phytate, also called phytic acid, is an anti-nutrient that’s found in a range of whole grains, seeds, legumes, and nuts. Within those categories, however, the phytate content of foods can vary greatly.

As an anti-nutrient, phytic acid inhibits the absorption of several essential minerals, inducing; iron, zinc, calcium, and magnesium[*][*].

These minerals play a variety of essential roles in the health of your body. Some of the most notable include; immunity, blood cell formation, electrolyte balance, central nervous system function, DNA synthesis, and bone health[*][*][*][*].

However, even with all of these potential detriments to health, phytic acid does have some potential benefits.

One benefit of phytic acid is its role in reducing the risk of calcium-oxalate kidney stones by inhibiting calcium salt crystallization. In fact, observational studies show that there is an inverse relationship between dietary phytate intake and kidney stone formation[*].

In addition, phytic acid has been studied as a potential anti-carcinogenic substance. One study on colorectal cancer found that phytic acid was able to up-regulate specific pathways which induce apoptosis (cell death) of cancer cells[*].

#5 Saponins

Saponins are found widely in whole grains as well as legumes. They get their name from their ability to form stable, soaplike foams in water solutions.

Like most compounds discussed, saponins exhibit both beneficial and potentially harmful properties.

From a health benefits standpoint, saponins may help reduce cholesterol, blood sugar, and protect your body against certain types of cancers.

A saponin-rich diet may also protect against dental carries, and acute treatment can be used in cases of lead poisoning. In addition, saponins appear to have an inverse relationship with the incidence of kidney stones[*].

However, as an anti-nutrient, saponins not only bind certain minerals but may also cause digestive disturbances like gas or bloating. It should be noted, however, that these disturbances have been reported in animal, not human, trials[*].

#6 Tannins

Tannins are actually a source of antioxidants. They’re a class of polyphenols that are water-soluble and found in many plant-based foods.

Antioxidants are an essential component of the human system as they help to balance oxidative stress. Without the help of antioxidants, oxidation would run wild in your body, and you would experience a wide range of health concerns[*].

However, although they can act as a source of antioxidants, tannins can also negatively impact your health due to their inhibitory effect on certain enzymes. They also cause impaired utilization of vitamins and minerals and precipitate proteins — separating them in solution.

Tannins have been implicated in the progression of certain types of cancers(esophageal and cheek). However, other research supports the use of tannins as anti-carcinogenic.

Tannins act as protection molecules in plants against fungi and bacteria. As such, they offer natural antifungal and antibacterial properties to your body –including your GI tract.

In addition to their anti-carcinogenic and antioxidant behavior, tannins may also support lipid metabolism, liver health, and immune response[*].

How to Reduce Anti-Nutrients in Food

As you can see, most foods that are high in anti-nutrients are also high in nutrients like vitamins, minerals, and fiber. Instead of avoiding foods that contain anti-nutrients, another option is to prepare your food in a way that reduces the number of active anti-nutrients.

There are several techniques that work to achieve this, including:


Boling may be the fastest way to decrease the anti-nutrient content in your foods.

Anti-nutrients like tannins, oxalates, saponins, and lectins can be effectively deactivated with proper boiling[*][*][*][*].

For glucosinolates, boiling is the most effective way to reduce levels in brassica vegetables, along with the act of chopping the veggies[*].

Boiling water, and other forms of high-heat activation, does a wonderful job of deactivating anti-nutrients. Depending on the food item, you may want to boil for longer or short periods of time to make sure the anti-nutrients are properly degraded.


Many people soak foods like beans before they cook them to enhance their digestibility. One of the benefits of soaking is the effect it has on anti-nutrients, especially those found on the skin of beans.

Many anti-nutrients are water-soluble, therefore allowing an overnight soak can significantly reduce the number of anti-nutrients left in the food.

But beans aren’t the only type of food that can be soaked to reduce anti-nutrient levels. Some vegetables also benefit from a good soak to reduce oxalate levels as well[*].

In general, soaking is a great option for reducing levels of oxalates, phytates, tannins, saponins and lectins[*][*][*][*].


Sprouting is a great way to reduce phytates, tannins, and lectins in your food. During the sprouting process, the seeds of the plant germinate and put out shoots. This phase in the life cycle of the plant creates more bioavailable nutrients, increasing the nutrient density of the food.

A valuable side effect of the sprouting process is the natural breakdown of some of the anti-nutrients. As anti-nutrients breakdown, mineral bioavailability increases.

Sprouting is an excellent option for seeds and legumes[*].

The sprouting process is slightly more involved than simply soaking, but is still pretty straightforward:

  1. Rinse your seeds or beans.
  2. Soak them (using a ratio of three parts water to one part seed or bean) for around 12-24 hours depending on the type of seed or bean.
  3. Drain the water, and allow the seeds to sit in either a mason jar or a sprouting container.
  4. Repeat the process of rinsing and draining a few more times until the seeds or beans are sprouted as desired.


Along with sprouting, fermentation is another way to enhance the bioavailability of nutrients in your food. And likewise, it is also a great way to reduce anti-nutrient content at the same time.

Fermentation is a process that’s been around for thousands of years. During the fermentation process microorganisms (either naturally occurring or added) digest the carbohydrates in the food.

Along with carbohydrate digestion, anti-nutrients like phytates and lectins tend to be degraded[*][*].

A quick google search can give you an easy, step-by-step guide to fermenting pretty much any food you want, although this technique tends to work best with vegetables or dairy.

Should You Avoid Anti-Nutrients?

Whether or not you should avoid anti-nutrients is a hot topic. For some people, anti-nutrients may be cause for concern, while for others they may actually help boost health.

If you’re someone who has digestive issues or is prone to kidney stones, you may do well by taking some extra steps to reduce the anti-nutrient content of your food.

However, if your digestion is strong and there is no concern for kidney stones anti-nutrients may not be that big of a deal.

Although they are termed “anti-nutrients,” many of these compounds actually impart some impressive health benefits.

Antioxidants like tannins can support the health of your cells, boost your immune response, and may even protect against cancer[*].

While saponins may provide benefits to your oral health, helping to ward off plaque and dental carries[*].

If you’re on the fence about anti-nutrients, or one type in particular, a great rule of thumb is to try an elimination diet. Depending on which anti-nutrient is of concern for you, you can try to reduce the content in your food using one of the techniques mentioned above, or simply avoid foods high in that specific anti-nutrient all together.

However, this type of elimination only needs to take place over a week or two. Since anti-nutrients are so abundant in a wide variety of foods, you may find yourself eliminating too many valuable nutrient sources.

If you do find that you feel better when eliminating anti-nutrients from your system, it’s likely due to an underlying issue in either your digestion or elimination processes. From there, you can seek out the advice of a health care practitioner or nutritionist to guide you.

Overall, however, anti-nutrients seem to get a worse reputation than they deserve. With the understanding that many cooking methods degrade anti-nutrients naturally, along with the potential health benefits, anti-nutrients don’t necessarily need to be on your watch list.


Anti-nutrients are labeled as such due to their tendency to inhibit the absorption of nutrients.

While this tendency may cause a slight hit to the nutritional value of your food, there are some benefits of anti-nutrients that can’t be ignored.

Research shows that these compounds can support your immune system, act as antioxidants, support oral health, decrease inflammation, and much more.

Unless you know you are sensitive to one or more of these compounds, they’re likely safe to consume. And when in doubt, you can decrease your anti-nutrient intake by boiling, sprouting, fermenting, or soaking your food.

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