Anti-Nutrients

by | May 6, 2024 | Nutrition, Real Food

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Anti-nutrients are a natural part of many plants’ defense mechanisms, but they are not inherently harmful if consumed in moderation and with proper preparation.

We all want and need nutrients. Nutrients allow our body to function properly and contribute to overall vitality. But what about anti-nutrients? What are they, and should they be avoided?  

Anti-nutrients are natural or synthetic compounds found in a variety of foods, particularly in plant-based foods, that can interfere with the absorption of vitamins, minerals, and other nutrients. They can also inhibit digestive enzymes, potentially leading to digestive disorders if consumed in large quantities. Those who adhere to the carnivore diet tribe often cite anti-nutrients as a reason to avoid all plants and solely consume meat. Do anti-nutrients make a plant-based diet a bad idea? 

Despite their name, anti-nutrients are part of the natural defenses of plants and are not necessarily harmful. They primarily evolved as a defense mechanism for plants, helping to protect them from pests, insects, and from certain bacteria. By inhibiting the ability of animals (including humans) to digest these plants fully, anti-nutrients can reduce the likelihood that a type of plant will be completely consumed and destroyed, thereby ensuring the survival and propagation of the species. 

Many everyday foods contain anti-nutrients, although they are predominantly found in plant-based foods. Some common examples include: 

  1. Phytates (Phytic Acid): Found in whole grains, seeds, legumes, and some nuts, phytates can bind to minerals like zinc, iron, magnesium, and calcium, preventing their absorption. 
  2. Tannins: These are polyphenols found in teas, coffees, and some legumes and grains. Tannins can inhibit digestive enzymes and reduce iron absorption. 
  3. Oxalates (Oxalic Acid): Found in foods like spinach, rhubarb, and beetroot, oxalates can bind with calcium and prevent its absorption, sometimes leading to the formation of kidney stones. 
  4. Lectins: Present in all food plants, especially in seeds, legumes, and whole grains, lectins are known to resist breaking down in the gut and can bind to the intestinal lining, potentially causing digestive issues. 
  5. Goitrogens: Found in cruciferous vegetables like broccoli, Brussels sprouts, and cabbage, goitrogens can interfere with thyroid gland function, particularly in regulating the uptake of iodine. 

Research indicates that vegetarians consuming a diet rich in plant-derived anti-nutrients often do not exhibit deficiencies in essential minerals like iron and zinc, suggesting that their bodies may adapt by enhancing mineral absorption in the digestive tract. However, other research has found that vegetarians do generally have lower iron stores and zinc levels in their blood compared to non-vegetarians. The absorption of zinc and of the type of iron found in plants can be influenced by the presence of inhibitors like phytates. 

Although anti-nutrients can interfere with nutrient absorption, it’s important to recognize the potential health benefits of anti-nutrients. Phytates, for instance, are associated with reduced cholesterol levels, moderated digestion speeds, and stabilized blood sugar levels. Furthermore, many anti-nutrients possess antioxidant and anticancer properties, suggesting that completely avoiding them may not be beneficial for health.

These and many other health benefits of plant foods outweigh the potential harm of anti-nutrients for most populations, and it’s almost always a good idea to eat a variety of nutritious foods daily. Fortunately, the impact of antinutrients can be minimized with proper food preparation techniques. Here are some effective methods: 

  1. Soaking: Soaking beans, grains, and seeds overnight can reduce their phytate content significantly. This process activates phytase enzymes, which break down phytates, thus enhancing mineral availability. 
  2. Sprouting: Similar to soaking, sprouting further reduces anti-nutrient content in seeds, grains, and legumes, and can also increase the content of beneficial nutrients. 
  3. Fermentation: Fermenting foods is another effective way to decrease anti-nutrients. Fermentation involves the breakdown of complex proteins and carbohydrates by bacteria and yeast, making these foods easier to digest and their nutrients more accessible. 
  4. Cooking: Simply cooking food can reduce the level of anti-nutrients. For instance, boiling removes some anti-nutrients in spinach and other leafy greens. 
  5. Pairing Foods: Combining foods wisely can also mitigate the effects of anti-nutrients. For example, eating vitamin C-rich foods like bell peppers or citrus fruits with iron-rich legumes can enhance iron absorption. 

Anti-nutrients are a natural part of many plants’ defense mechanisms, but they are not inherently harmful if consumed in moderation and with proper preparation. Understanding how to prepare and combine foods can significantly mitigate the effects of anti-nutrients and ensure that you reap the maximum nutritional benefits from your meals.

Emily Rhodes, MPH, RD

Emily Rhodes, MPH, RD

Position

Emily Rhodes, MPH, RD, our Food and Nutrition Writer, is a Registered Dietitian and Clinical Nutrition Manager at Keck Medicine of USC in Arcadia, CA. You can find her at the barn or in the grocery aisle reading a label.

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