Since 2020, Josh and I have experimented with various diets—carnivore, vegan, vegetarian—but ultimately found the best results with an animal-based approach. With so much focus today on the benefits of plant-based diets, I discovered something surprising: anti-nutrients. These natural compounds, commonly found in many plant-based foods, can interfere with your body’s ability to absorb essential minerals, which could lead to health imbalances.
One podcast that truly opened my eyes to this was a conversation between Dr. Paul Saladino and Sally K. Norton, who explained the potential dangers of consuming too many oxalates—especially if you enjoy foods like spinach, kale, almonds, chocolate, and peanut butter. Sally highlighted how these oxalates can build up in the body and disturb mineral balance, particularly calcium and magnesium absorption. If you're a fan of those types of smoothies, it's worth a listen!
On an animal-based diet, our “vegetables” are actually fruits like avocado, cucumber, olives, and sauerkraut—foods naturally low in anti-nutrients. This approach simply works better for us and supports our overall well-being.
In this blog, I’ll explore the role of anti-nutrients, their sources, and how they impact mineral absorption, especially calcium and magnesium. Also listen to Josh and I discussing this topic on our podcast.
What Are Anti-Nutrients?
Anti-nutrients are natural compounds in plant foods that serve as a defence mechanism against pests and diseases. While they help plants survive, they can inhibit our body’s ability to absorb essential minerals like calcium, magnesium, and iron. Some common anti-nutrients include oxalates, phytic acid, gluten, and lectins. Though most plant foods contain them, knowing how they affect your body can help you make informed dietary decisions.
How to Spot Mineral Deficiencies on a HIGH Anti-Nutrient Diet
Symptoms from High Anti-Nutrient Diet:
Fatigue and Low Energy: Iron is critical for oxygen transport in the blood. If anti-nutrients block iron absorption, it can lead to iron deficiency anaemia, characterised by constant fatigue, weakness, and difficulty concentrating.
Muscle Cramps and Weakness: Magnesium plays a key role in muscle and nerve function. A diet that interferes with magnesium absorption can result in muscle cramps, spasms, or a sense of weakness, especially during exercise or physical exertion.
Bone Pain and Weakness: Calcium deficiency, caused by anti-nutrients like oxalates binding to calcium, can lead to weakened bones, joint pain, and an increased risk of osteoporosis over time. People may also experience more frequent fractures or bone-related issues.
Achy Joints: As Sally K. Norton discussed, high oxalate intake can lead to oxalate deposits in the joints, which can cause inflammation and pain similar to arthritis.
Digestive Issues: Anti-nutrients may also cause bloating, gas, and discomfort due to their ability to interfere with nutrient absorption in the gut. This can worsen symptoms of malabsorption.
Poor Immune Function: Magnesium and iron are crucial for immune health. A reduction in their absorption may make people more prone to infections and illnesses as their immune system weakens.
The Key Anti-Nutrients and Their Impact
1. Oxalates
Oxalates are commonly found in spinach, beets, sesame seeds, and soybeans. These compounds bind to calcium, forming calcium oxalate crystals, which are insoluble and cannot be absorbed by the intestines. This reduces calcium availability and may contribute to the formation of kidney stones. Studies have shown that high oxalate intake can significantly lower the bioavailability of calcium and magnesium, leading to deficiencies.
2. Phytic Acid (Phytate)
Phytic acid, found in whole grains, seeds, and legumes, can bind to minerals such as magnesium, calcium, iron, and zinc, forming insoluble complexes that are excreted rather than absorbed. In one study, phytic acid was shown to reduce magnesium absorption from bread by 20-50%, especially in whole-meal and brown bread, which contain naturally higher levels of phytic acid. This can lead to deficiencies in individuals relying heavily on phytic acid-rich foods.
"reduce magnesium absorption from bread by 20-50%"
3. Gluten
Gluten, a protein found in wheat, barley, and rye, is not easily digested and can trigger an autoimmune response in susceptible individuals, such as those with celiac disease. Gluten intolerance can lead to nutrient malabsorption, especially of calcium and magnesium, contributing to mineral deficiencies.
Gluten can trigger thyroid antibodies through a process linked to leaky gut (check out episode 4 of our Podcast). In a healthy gut, small spaces between intestinal cells allow only tiny particles to pass into the bloodstream. However, factors like stress, certain foods, and dysbiosis can increase a protein called zonulin, which widens these gaps, allowing larger, undigested particles, such as gluten, to enter the bloodstream. The immune system recognizes gluten as foreign and creates antibodies against it. Due to molecular mimicry, these antibodies may also attack the thyroid gland, as gluten and thyroid enzymes share similar structures, potentially contributing to autoimmune thyroid diseases.
The inflammation caused by gluten can prevent proper absorption of nutrients, making it important to avoid gluten-containing foods if you autoimmune issues.
4. Lectins
Lectins, present in legumes (beans, lentils, peanuts) and whole grains, bind to carbohydrates and can interfere with nutrient absorption. They are resistant to digestive enzymes and can damage the intestinal lining, leading to gut dysbiosis and impaired mineral absorption. For example, studies suggest that lectins can prevent proper calcium and magnesium absorption, further exacerbating deficiencies in individuals who consume a high lectin diet.
Sources of Anti-Nutrients
Anti-nutrients are abundant in a wide variety of plant-based foods:
Oxalates: Spinach, sesame seeds, soybeans, beets
Phytic Acid: Whole grains, legumes, seeds (pumpkin, sunflower)
Gluten: Wheat, barley, rye
Lectins: Beans, peanuts, soybeans, whole grains
How Much Magnesium and Calcium Should You Supplement?
Given the role of these anti-nutrients in inhibiting mineral absorption, it is crucial to ensure adequate intake of calcium and magnesium, especially if your diet is high in these compounds.
Magnesium: Daily intake recommendations range from 300-400 mg for adults. If your diet is rich in oxalates and phytic acid, supplementation may be necessary to offset the reduced absorption.
Calcium: Recommended intake is about 1,000-1,200 mg per day. Consuming calcium-rich foods like dairy or calcium-fortified products can help compensate for the loss caused by oxalates and phytates.
Conclusion: Finding Balance
Irrespective of the science, if you are feeling your best on a plant-based diet, then do not change a thing! This is some science and how having too much anti-nutrients made us feel.
Anti-nutrients aren't inherently "bad." In fact, many plant foods that contain them also offer significant health benefits, such as fiber, vitamins, and antioxidants. However, understanding their impact on mineral absorption is crucial for maintaining optimal health. By tweaking your diet—cooking methods like soaking and fermenting, and considering mineral supplementation—you can strike a balance that ensures you're getting the nutrients you need without the downsides.
If you're eating a heavily plant-based diet and struggling with symptoms like fatigue, joint pain, or digestive issues, consider adjusting your intake of these anti-nutrients. It might be the key to unlocking better health. Go and grab your self some Naru Revive!
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