Many of us consider the nutritional value of foods as we choose them. For example, you might add some strawberries to your morning cereal to get a boost of vitamin C and other nutrients (besides the nice flavor!)
However, foods also contain naturally occurring compounds that scientists refer to as anti-nutrients. Plants use these compounds for protection against disease and for storing nutrients. But when humans and non-ruminant livestock consume such plants, these anti-nutrients may interfere with the absorption of essential nutrients. It is important for crop breeders to consider anti-nutrients in crops because of their impact on human, animal, and environmental health.
Effect of anti-nutrients on human diets
Human diets high in plant-based foods can result in moderate to high intakes of anti-nutrients. Some common anti-nutrients are known as phytates, tannins, lectins, and phytoestrogens. For people who eat a wide variety of foods in their diets, anti-nutrients are not a concern. In addition, common food preparation methods such as soaking, germinating, fermenting, and cooking reduce levels of anti-nutrients in foods.
For individuals with existing nutrient deficiencies or conditions that affect nutrient absorption, anti-nutrients can further deplete their stores of essential nutrients, and their ability to absorb nutrients when digesting meals.
Studies about human nutrition and anti-nutrients have conflicting results. We know anti-nutrients can negatively impact nutrient absorption. However, diets rich in grains, legumes, nuts, fruits, and vegetables containing high amounts of anti-nutrients can be especially healthy diets. The Dietary Approaches to Stop Hypertension (DASH) diet is one such diet. Human clinical research has shown the DASH diet reduces blood pressure in adults with hypertension. There is substantial evidence supporting the positive health benefits of the DASH diet. Thus, the DASH diet is recommended by the USDA and NIH as a healthy eating plan to prevent and control hypertension.
Not everyone has access to a diverse diet, food fortification, or supplementation. Such situations can result in micronutrient deficiencies. Health officials consider iron deficiency one of the leading contributors to global disease. Over 1.2 billion cases of iron deficiency anemia were reported in 2016.
One of the tools to tackle micronutrient deficiency is breeding staple crops, such as corn or beans, to be higher in micronutrients. Breeders must increase the amounts of micronutrients – like iron – without increasing the amounts of anti-nutrients that would diminish the bioavailability of the targeted micronutrients.
For example, phytic acid is an anti-nutrient of concern. It binds with important nutrients like iron in the digestive tract. That limits the absorption of iron by the body.
Although breeders were able to create a new high-iron bean, eating the bean did not greatly improve the iron status among Rwandese women in the studies. The high-iron bean had 50% more iron, but the breeding did not decrease the phytic acid content enough to counter the anti-nutritive effect of phytic acid. So, while the iron was there, the women’s’ bodies couldn’t absorb it well.
Effect of anti-nutrients on animal diets
Livestock feed high in anti-nutrients compromises non-ruminant livestock health. It can also contribute to nutrient excess in livestock waste and environmental pollution. Creating low anti-nutrient crops can also reduce the amount of minerals removed from agricultural soils. That may reduce the amount of fertilizer needed. With less fertilizer, we reduce the chances of environmental pollution and extract less from our global reserves of critical limited resources. Researchers working towards a healthy and sustainable food system must consider anti-nutrients.
Anti-nutrient content can impact the digestibility and nutrient absorption in animal feed. Sorghum is a popular animal feed for poultry and swine production. However, sorghum varieties can have limited digestibility due to the presence of anti-nutrients. Enzymes are often incorporated into feed to improve nutrient absorption.
Anti-nutrients are naturally occurring and are important to human, animal, and plant health. Their effect on human and animal health can sometimes be negative because they interfere with the absorption of important nutrients. A diverse diet is the best way to avoid nutrient deficiencies but isn’t possible for everyone. It is critical to consider anti-nutrients in research, such as identifying and developing crop varieties low in anti-nutrients, while consumers focus on diversifying their diet.
Answered by Julianne Kellogg and Emily Klarquist, reviewed by Victor Raboy, Washington State University
About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified, professionals in the areas of growing our world’s food supply while protecting our environment. We work at universities, government research facilities, and private businesses across the United States and the world.