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What Are Antinutrients? (And How Do They Affect Me?)

When I had reversed rheumatoid arthritis but still had chronic joint pain, I started researching other root causes, and I stumbled upon antinutrients

You see, I felt better when I didn’t eat. 

But that wasn’t a sustainable long-term solution. 

In fact, when I got a bad stomach bug in college and didn’t eat for 3 days, my pain went away for days afterward

For a couple of years after that, my pain would go away for the rest of the day after I gave blood. 

I had food allergy and food sensitivity testing. Even after eliminating those, all it did was resolve the stiffness in my joints. I still had a lot of pain. 

RELATED: How to Handle Food Loss

Sprouted Rice

I kept a food diary for a few different practitioners but couldn’t see the pattern of food intake with my flares… until I learned about antinutrients. 

Let’s look at the common antinutrients In plant foods. Then I’ll share what helped me. 

Please don’t limit your diet unnecessarily. It’s so important to maintain diversity in your diet. For healthy people with good digestion, antinutrients are not something to fear.

However, if you’re struggling with mystery symptoms and you’re not sure what is causing them, you may want to rule out antinutrients alongside your healthcare practitioner. This is not medical advice.

What Are Antinutrients? 

Antinutrients are compounds that plants use to either help them absorb nutrients from the soil or deter pests

However, when we consume too many of certain antinutrients, these plant defense mechanisms can have adverse effects on our bodies. They have the potential to reduce nutrient absorption, block vitamins and minerals, and/or block digestive enzymes. 

Antinutrients are found in many plant foods like:

  • Fruits 
  • Vegetables
  • Nuts
  • Legumes
  • And more
long term storage beans

Not all antinutrients have the potential to be bad for you. Some of the more inert antinutrients are:

  • Polyphenols
  • Tannins 
  • Saponins
  • Glucosinates

Some can be easily reduced with typical cooking methods.

Even some of the potentially harmful antinutrients can still work in your favor. They’re similar to antioxidants where they may challenge your body in some way, but overall they have a positive effect in the right portions. 

A healthy person can handle antinutrient compounds in moderation. 

In some cases, you may not need to cut foods containing antinutrients from your diet if you prepare them the right way

But I didn’t know how. Read about other mistakes I’ve made in my health journey here. 

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What Antinutrients Harm 

When you consume too many of a particular antinutrient or neglect to use the proper cooking methods, antinutrients can cause you issues.

Some of my friends have tried doing a vegetarian or vegan diet. They felt better for two or three months because they were eating cleaner, but then they started to feel worse after that. In hindsight, I wonder if they were having a build-up of one of these antinutrients that was causing them to feel bad.

For example, antinutrients can bind and/or block you from absorbing these nutrients

  • Zinc
  • Calcium 
  • Magnesium
  • Iron 
  • Phosphorus 
  • Potassium

Specifically, phytates can steal your minerals. You can learn all about phytates and phytic acid in this post. 

Long-term consumption of antinutrients, especially without the correct cooking methods, can lead to nutrient deficiencies. For example, blocked iron absorption can lead to anemia. 

On the other hand, some hypothesize that antinutrients are correlated with leaky gut. This may be because lectins and oxalates are sharp. They are meant to deter bugs who bite into their plants, but they might poke holes in your fragile gut wall. 

man with stomach pain

Common Antinutrients in the Standard American Diet

In addition to phytates, the common antinutrients that you might be consuming are lectins, salicylates, and oxalates. Let’s take a closer look at each.


Lectins are probably the nutrient you’ve heard about the most in the media.

Dr. Steven Gundry popularized the low-lectin diet. 

Some common high-lectin foods are:

  • Tomatoes
  • Peppers 
  • Gourds 
  • Legumes  
  • Whole grains
  • Seeds 

Glutens might be one of the most difficult-to-digest lectin plant proteins. (But just because you react to gluten doesn’t mean you are reacting to the lectins in it.) 

whole grains in scoops


Salicylates are a common plant antinutrient. 

One of the telltale signs of salicylate intolerance is a reaction to aspirin. Aspirin comes from willow bark which is high in salicylates. 

Some common high-salicylate foods are:

  • Berries 
  • Herbs 
  • Broccoli
  • Coconut 
  • Corn  

Some people are so salicylate intolerant that they react to skin care products that have herbs that are high in salicylates. 



Also called oxalic acid, you’ve probably heard about oxalates if you or someone you love has kidney stones. Sometimes, they’re also called calcium oxalate. 

Oxalates are sharp crystals in plants. They repel bug pests from eating them. 

However, kidney stones are not the only problem that high levels of oxalates in the body can cause. In severe cases,  too much oxalic acid may result in hypothyroidism (aka Hashimotos.) Some hypothesize that oxalates can get lodged in the soft tissues and joints. 

Some common high oxalate foods are:

  • Spinach 
  •  Beets
  • Curly kale
  • Swiss chard 
  • Sweet potatoes 
  • Rhubarb 
  • Peanuts

I was eating pretty high oxalate on a grain-free diet.

Note: Never quit oxalates all at once. You’ll need to wean down your consumption slowly so that you don’t end up in the emergency room. 

The Antinutrients I Was Reacting To

I had an organic acids test in my early 20s that tested some of the common oxalate markers. But my levels came within range so I didn’t try a low oxalate diet then. A more experienced practitioner would have known that a negative test result doesn’t mean that you don’t have an oxalate build-up in your body. Only a positive result confirms it. 

Over a decade later, I heard some practitioners discussing oxalates on one of those virtual summits, and I had almost every symptom they listed:

  • Joint pain 
  • Eye irritation
  • Autoimmunity
  • Persistent candida
  • Electrolyte deficiencies
  • Random Interstitial Cystitis
  • Fatigue 
  • Migraines 
  • Occasional sandy stool

We suspect that my oxalate intolerance was caused by Mold Poisoning. 

sore knee

The pathways that your body processes oxalates through are in your liver and kidneys. This may be why some people who don’t process oxalates well end up with kidney stones

When I looked over my food journals and reviewed my bad flare days, the day before the flare I frequently had multiple high oxalate foods

What To Do About Antinutrients 

The first step before you make any changes to your diet is to keep a food journal along with your symptoms

Depending on your immune system function you may have an immediate response to antinutrients or you may have a delayed response up to four or five days. 

Keep a symptoms journal to record your symptoms. If it’s helpful, you can abbreviate by putting the first letter of phytates, lectins, salicylates, and oxalates to mark foods that are high. For example:

  • Kidney beans – L
  • Brown Rice – P, O 
  • Broccoli – S 

You will want this data to be able to share it with your doctor if you start to see a pattern of what you’re reacting to. 

Stay tuned for next month’s post on how to reduce them from your diet if you start to see patterns. 

The overall goal would be to reduce your intake of the antinutrients you are reacting to while you address whatever the root cause is for you. Long term, you’ll want to be able to add these foods back into your diet in moderation and prepared right. 

Check out the next post in this series for how to reduce antinutrients in your diet.

Do you suspect that you could be reacting to some antinutrients? Did you find the root cause? 

More on Unexplained Illness 


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Baenkler H. W. (2008). Salicylate intolerance: pathophysiology, clinical spectrum, diagnosis and treatment. Deutsches Arzteblatt international, 105(8), 137–142. 

Goldman, M., & Doering, G. J. (1979). The effect of dietary ingestion of oxalic acid on thyroid function in male and female Long-Evans rats. Toxicology and applied pharmacology, 48(3), 409–414.  

Katoh, R., et al. (1993). Birefringent (calcium oxalate) crystals in thyroid diseases. A clinicopathological study with possible implications for differential diagnosis. The American journal of surgical pathology, 17(7), 698–705.  

Muntz F. H. (1999). Oxalate-producing pulmonary aspergillosis in an alpaca. Veterinary pathology, 36(6), 631–632.

Preet, K., & Punia, D. (2000). Antinutrients and digestibility (in vitro) of soaked, dehulled and germinated cowpeas. Nutrition and health, 14(2), 109–117. 

Pusztai A. (1993). Dietary lectins are metabolic signals for the gut and modulate immune and hormone functions. European journal of clinical nutrition, 47(10), 691–699. 

Swain, A. R., Dutton, S. P., & Truswell, A. S. (1985). Salicylates in foods. Journal of the American Dietetic Association, 85(8), 950–960. 

Zimmerman, L. E., & Johnson, F. B. (1958). Calcium oxalate crystals within ocular tissues; a clinicopathologic and histochemical study. A.M.A. archives of ophthalmology, 60(3), 372–383.  

Unless otherwise credited, photos are owned by the author or used with a license from Canva or Deposit Photos.

3 thoughts on “What Are Antinutrients? (And How Do They Affect Me?)”

  1. If you are interested in delving into this topic further, I can’t recommend Sally K. Norton’s book, Toxic Superfoods, on oxalates enough!

  2. Jessie Weaver

    That is really helpful, SJ! My daughter has been having a lot of wild medical symptoms we can’t pin down. I’m definitely going to get her to keep a food journal and see if we can pin down any antinutrients that are hurting her.

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