Understanding Anti-Nutrients

Anti-Nutrients: Should You Be Concerned?

Applying nutrition research to one’s diet is complicated because foods are often studied in isolation, unlike how we consume them. Even within a single food, various vitamins, minerals, and phytochemicals interact, and this complexity increases when combining different foods. This in addition to individual factors such as nutrient needs, genetic makeup, and the gut microbiome, no wonder we are confused about what to eat!

One category of compounds that often raises concerns is anti-nutrients. But what exactly are they, and should you be worried about consuming them? Let’s dive into the science behind these compounds, how they affect your body, and how to minimize any potential downsides while still enjoying nutrient-rich foods.

What Are Anti-Nutrients?

Anti-nutrients are naturally occurring compounds in plant-based foods that can interfere with the absorption of essential nutrients like minerals. However, they also provide health benefits, such as acting as antioxidants and supporting immune function.

The key is understanding how to properly prepare and balance these foods in your diet.

Common Anti-Nutrients and How to Reduce Their Impact

Lectins – For the most part, lectins are not broken down by enzymes or bacteria in the gastrointestinal tract which may contribute to their anti-nutrient properties. Lectin content can vary based on plant species, age, where it’s grown, disease susceptibility, and genetic resistance. One study showed that roughly 8-18% of 500 people tested were sensitive to various lectins. It is important to note that many studies on lectins are done using high doses in their raw form which is not how they are primarily consumed. When studies using human subjects are given cooked lectins, they often do not show the same results.

Found in: Legumes, cereal grains, seeds, nuts, fruits, vegetables
Potential concerns:
- May compromise the intestinal lining, contributing to inflammation
- Can trigger immune responses in sensitive individuals
- May interfere with nutrient absorption
How to reduce lectins:
- Soaking, sprouting, fermenting, boiling, and high-pressure cooking
- Example: Boiling legumes for one hour at 203°F reduces lectins by ~94-100%
- For high lectins sources like soybeans and kidney beans, reduced cooking temperatures do not affect lectin content as much as boiling or autoclaving

Oxalates- Oxalates are substances produced by the body and obtained through diet. They are primarily excreted through urine and urine oxalates are mostly from the oxalates we produce versus consume. Dietary oxalates exist as soluble or insoluble salts, with the soluble form binding to minerals like calcium and magnesium, potentially hindering absorption. The most well-known anti-nutrient property of oxalates is the potential to contribute to calcium oxalate stone formation in the kidneys after absorption in the digestive tract. Oxalate content in foods varies based on plant type, season, and growing conditions, leading to inconsistencies in reported levels. The amount of soluble versus insoluble oxalates in food, along with measurement techniques and the absence of standardized databases, further contribute to these discrepancies. Ongoing research continues to refine our understanding of oxalates and their effects on health.

Found in: Spinach, Swiss chard, beet greens, rhubarb, nuts, legumes, cereal grains, sweet potatoes, potatoes
Potential concerns:
- Can bind to minerals like calcium, iron, and magnesium, reducing absorption
- May contribute to kidney stone formation in susceptible individuals
How to reduce oxalates:
- Boiling and steaming decrease oxalate content more effectively than dry cooking
- Eating oxalate-rich foods with calcium, magnesium, and potassium helps prevent absorption and kidney stone formation

Phytates- Phytates are compounds used in plants as a storage form of phosphorus which can bind to minerals like iron, zinc, calcium, and copper, hindering absorption and thus making them ‘anti-nutrients.’ However, this same property also gives them antioxidant benefits. Their levels vary by species, growing methods, and seasons.

Found in: Legumes, cereal grains, pseudocereals (quinoa, millet, amaranth), nuts, seeds
Potential concerns:
- Can bind to minerals like iron, zinc, calcium, and copper, reducing absorption
How to reduce phytates:
- Soaking, fermentation, sprouting, germinating, and cooking
  - Note: soaking will also leach out iron and zinc as well, but these losses can be mitigated by using the water during the remaining parts of food preparation.
- Consuming phytate-rich foods with vitamin C enhances iron absorption
- Fermented foods containing probiotics (e.g., L. plantarum) help improve mineral absorption

Tannins- Responsible for the astringent taste in many plant foods, tannins can bind to minerals like iron, copper, and zinc. However, they can also support immunity, detoxification, and protect against cancer and cardiovascular disease. Their levels vary by plant variety, region, farming and processing methods, storage, and for tea infusion time, peaking at 4–5 minutes.

Found in: Tea, cocoa, grapes, berries, apples, stone fruits, nuts, beans, whole grains
Potential concerns:
- Bind to minerals such as iron, copper, and zinc, reducing their absorption
How to reduce tannins:
- Cooking and processing can decrease tannin content
- Since many tannins are often consumed in raw form, pairing tannin-rich foods with vitamin C enhances iron absorption
- Drinking tea away from meals minimizes interference with iron absorption

Phytoestrogens

Phytoestrogens are compounds found in plants that have a similar structure to estrogen, therefore can mimic estrogen in the body. This poses the concern that phytoestrogens can act as endocrine disruptors and contribute to certain cancers. Though more research is needed, phytoestrogen intake, particularly soy in its whole form such as tofu, tempeh and edamame, have actually been associated with reduced risk of breast cancer due to its ability to bind to certain estrogen receptors that have antiproliferative effects. Other potential health benefits include reduced risk of cardiovascular disease, metabolic syndrome, type 2 diabetes, benefits for bone health, and improvement in menopausal symptoms.

Found in: Soy products, flaxseeds, nuts (negligible amounts), fruits, and vegetables (negligible amounts)
Potential concerns:
- Can mimic estrogen in the body, raising concerns about hormonal effects especially in concentrated amounts and/or highly processed forms
Potential benefits:
- May reduce the risk of breast cancer, cardiovascular disease, metabolic syndrome, and type 2 diabetes
- Supports bone health and menopausal symptom relief
How to optimize intake:
- Boiling, steaming, and fermenting help activate beneficial compounds

Goitrogens

Goitrogens, found in medications, environmental toxins, and certain foods, are classified as anti-nutrients due to their potential to interfere with thyroid function. Cruciferous vegetables contain glucosinolates, which may inhibit iodine uptake, but their levels are typically not high enough to cause issues unless iodine intake is low. Those with thyroid disease or at risk should ensure adequate iodine consumption from sources like seafood, seaweed, iodized salt, and dairy if tolerated. The impact of glucosinolates varies by vegetable type and preparation method, with Brussels sprouts and some kales containing higher levels compared to broccoli and cauliflower.

Found in: Cruciferous vegetables (kale, Brussels sprouts, cabbage, turnip greens, broccoli), millet, cassava
Potential concerns:
- May interfere with thyroid function by inhibiting iodine uptake
- More likely to be an issue for those with iodine deficiency
How to reduce goitrogens:
- Ensuring adequate iodine intake (from seafood, seaweed, iodized salt, or dairy if tolerated)
- Cooking reduces goitrogen levels

Key Takeaways

Anti-nutrients are not inherently harmful when consumed as part of a balanced, whole-foods diet.
Proper preparation methods (soaking, sprouting, fermenting, boiling, steaming) significantly reduce their effects.
Many anti-nutrient foods also provide essential nutrients, fiber, and antioxidants, contributing to an overall healthy diet.
If you have specific health concerns (e.g., autoimmune disease, kidney stones, nutrient deficiencies, thyroid issues), you may need to be more mindful of your intake and preparation methods.

Final Thoughts

I hope after reading this, you see that when properly prepared, anti-nutrient-rich foods are unlikely to be a concern in a balanced, whole-foods-based diet. Consuming a diverse range of fruits, vegetables, lean proteins, and healthy fats ensures a broad spectrum of nutrients, reducing the risk of deficiencies or anti-nutrient excess. Anti-nutrient rich foods also provide essential protein, fiber, vitamins, minerals, and antioxidants, contributing to an overall anti-inflammatory diet.

Individuals with specific health concerns such as autoimmune disease, kidney stones, or nutrient deficiencies may need to be more mindful of their intake and preparation methods. Just as plants have evolved protective mechanisms, so too have humans, allowing us not only to tolerate anti-nutrients but to benefit from them in ways we may not yet fully understand. Working with a functional medicine nutritionist can help you with food choices to optimize your nutrients based on your individual needs.

References