What's the Deal with Antinutrients in Plant-Based Foods?

Introduction

There’s this lesser known aspect of plant-based eating that can significantly impact the way you absorb nutrients, and these are components known as antinutrients. Antinutrients are naturally occurring compounds found in many plant-based foods that can interfere with the absorption of essential nutrients in the human body like iron, calcium, or zinc. They exist because they serve a protective role for plants, acting as a defense mechanism against pests, insects, and diseases (1). While these compounds are beneficial for plants, they can post challenges for those who heavily rely on plant-based foods for their nutritional needs.

Here, we detail the most common types of antinutrients, how they affect vitamin and mineral absorption, common foods they are found in, and ways to reduce antinutrient content.

Common Antinutrients in Plant-Based Foods

Antinutrients work by binding to essential minerals and nutrients, forming complexes that the body finds difficult to absorb. There are several types of antinutrients, each with unique effects on nutrient absorption:

Phytates (Phytic Acid)

Found in whole grains, legumes, nuts, and seeds, phytates can bind to minerals like iron, zinc, and calcium, reducing their bioavailability as a consequence (2). This binding can lead to potential deficiencies, especially in people who rely heavily on plant-based foods like vegans and vegetarians or in diets that lack significant variety. One study found that reducing the phytate content of cereal and legume-based foods increased iron absorption by 12-fold (3).  

Oxalates

Commonly found in spinach, beet greens, and certain nuts, oxalates can bind to calcium, affecting calcium absorption and forming these oxalate crystals that may contribute to kidney stones (4). Researchers compared calcium absorption in spinach and milk and found that the calcium absorption from spinach hovered around 5% whereas the calcium absorption from milk averaged 27.6% (5). This study shows that the calcium from spinach is less bioavailable than the calcium from milk, likely due to the presence of oxalates in spinach.

Tannins

Tannins are a class of antioxidant polyphenolic compounds that are present in tea, coffee, legumes, and some fruits (6). They can inhibit the absorption of non-heme iron, the type of iron found in plant-based foods, which is already less readily absorbed compared to heme iron from animal products (7).

Click here to read more about heme iron vs. non-heme iron absorption

Lectins

Lectins are proteins found in beans, lentils, and whole grains. In large amounts, they can interfere with nutrient absorption and cause digestive discomfort and inflammation (8). However, it has been shown that proper cooking methods such as soaking can significantly reduce lectin content in food (9).

For those following a plant-based diet, this reduced bioavailability caused by antinutrients can lead to serious deficiencies over time, especially if the diet is not properly managed. This makes it crucial to understand the role of antinutrients and to employ the strategies mentioned here to minimize their impact.

Catch up in The Journal Club with these posts about plant-based diets:

Plant-based diets: unlocking their potential while addressing the risks

A scientist’s 8 tips for a well-balanced plant-based diet

Symptoms of nutrient deficiencies: plant-based edition

Addressing common myths about vegan nutrition

Strategies to Reduce Antinutrients in Plant-Based Foods

While antinutrients are a natural part of many plant-based foods, there are several strategies that have shown to be effective to improve nutrient absorption:

• Soaking: Soaking grains, legumes, and nuts in water for several hours or overnight can help reduce the levels of phytates and other antinutrients (10). One study found that soaking peas for 12 hours reduced the phytate content by around 9% (11). This process of soaking activates enzymes that can break down these compounds, making the nutrients more bioavailable for our bodies to absorb.
• Sprouting: Sprouting involves germinating seeds, grains, and legumes by soaking them and keeping them moist until they begin to grow. This process not only reduces antinutrient levels, but also increases the availability of certain vitamins and minerals (12). A study from 2012 found that sprouting could reduce the phytate content by up to 81% in beans (13). Sprouting has also been shown to enhance the nutritional profile of foods like lentils, mung beans, and wheat berries.
• Fermenting: Fermentation is another effective method co-opted to reduce antinutrient content, though it was originally used in ancient times to preserve food. Foods like tempeh, miso, and sourdough bread undergo fermentation, which uses beneficial bacteria to break down antinutrients and improve digestibility. Sourdough fermentation can degrade antinutrients and therefore lead to greater nutrient bioavailability (14). Fermented foods also have other health benefits, including evidence of improved gut health (15).
• Cooking: Cooking methods such as boiling, steaming, and pressure cooking can reduce levels of certain antinutrients like lectins and oxalates due to exposure to high heat (16). For instance, boiling beans for a specific duration can inactivate most lectins, making them safe to consume. Similarly, boiling spinach can reduce its oxalate content by up to 87%, making its calcium more bioavailable (17). Although high heat is an effective method to degrade antinutrients, it can also destroy certain vitamins and minerals. It has been shown that steaming vegetables can retain more nutrients than boiling (18).  

The Role of Balanced Nutrition and Supplementation

While it's essential to reduce the impact of antinutrients through proper food preparation techniques, maintaining a balanced and varied diet is equally important. Consuming a wide range of plant-based foods ensures that you receive all the necessary nutrients while minimizing the effects of any single antinutrient.

However, in some cases, supplementation may be necessary to ensure adequate nutrient intake. High-quality supplements, like The Plant Based Essentials, are designed to provide essential nutrients that may be affected by antinutrients. For example, this all-in-one vegan supplement includes bioavailable forms of iron and zinc, ensuring that your body receives these critical minerals despite the presence of antinutrients in your diet.

Conclusion

Antinutrients are a natural part of many plant-based foods, and while they can pose challenges to nutrient absorption, they don’t completely ruin the benefits of a plant-based diet. By understanding what antinutrients are and employing strategies like soaking, sprouting, fermenting, and cooking in your meal prep routine, you can minimize their impact and ensure that your body receives the nutrients it needs.

Maintaining a balanced diet rich in a variety of plant-based foods, along with the appropriate use of supplements, can help you thrive on a plant-based diet while enjoying its health benefits. It’s important to be mindful of antinutrients, but don't let them discourage you from enjoying the benefits of plant-based eating.

If you’re looking for a supplement to support you on your plant-based journey, learn more about the plant-based essentials, our all-in-one vegan multivitamin, here.

References

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