There has been much research conducted lately on substances called “anti-nutrients”. The term anti-nutrients suggest what they are, whereas nutrients are substances that nourish plants and animals to grow and live, anti-nutrients are aptly named due to their ability to block the absorption of nutrients. They are found both in animal and plant-based foods. In plants, anti-nutrients are compounds designed to protect bacterial infections and dissuade certain insects from eating them. So, while they function to serve an evolutionary purpose for the plant, what effect do they have on us humans when we eat them?
But first thing is first. What are some examples of anti-nutrients? Examples of anti-nutrients include the following:
- Glucosinolates. Found in cruciferous vegetables (broccoli, Brussels sprouts, cabbage). They can prevent the absorption of iodine, which may then interfere with thyroid function and cause goiter. Those that suffer from hypothyroidism are most susceptible.
- Lectins. Found in legumes, lectins (beans, peanuts, soybeans). They can interfere with the absorption of calcium, iron, phosphorous, and zinc.
- Oxalates. Found in leafy green vegetables and tea. They can bind to calcium and prevent its absorption.
- Phytates (phytic acid). Found in whole grain, seeds, legumes and some nuts. They can decrease the absorption of iron, zinc, magnesium, and calcium.
- Saponins. Found in legumes and whole grains. They can interfere with normal nutrient absorption.
- Tannins. Found in coffee and tea. They can decrease iron absorption.
However, research has been less than conclusive of how much nutrient loss occurs not just in each individual, but in people as a whole. In other words, we don’t know how adversely affected my body would be compared to yours, or the person next to you, or humans as a whole. Further, evidence does exist that the effects vary among individuals based on their individual metabolisms, where they buy their food, and how they prepare their foods. Many anti-nutrients such as phytates, lectins, and glucosinolates can be removed or deactivated by soaking, sprouting, or boiling the food before eating. So behavioral patterns in food preparation matter.
Another consideration is that these anti-nutrients affect the absorption of nutrients consumed at the same meal. Therefore, it is smart to avoid eating large quantities of anti-nutrients at one meal, and to eat a balanced diet throughout the day with a variety of foods. I tell my clients this all the time, especially my bodybuilders who want to eat the same chicken, rice and broccoli at each meal. As omnivores, evolution has enabled us to develop enzymes that can process and digest most foods. So we need to take advantage of that.
However, keep in mind that anti-nutrients may also exert health benefits. Some of them have antioxidants, they increase our metabolism, and lower cholesterol, so avoiding them totally is not recommended. At the end of the day, the health benefits of eating these foods outweigh any potential negative nutritional effects. It would be absurd for me to tell clients to avoid eating broccoli – it is one of the world’s most powerful wonder foods. Eating a variety of nutritious foods daily and avoiding eating large quantities of a single food at one meal can help to offset minor losses in nutrient absorption caused by anti-nutrients.