Antinutrients in Nutrient-Rich Foods?
When we hear the word antinutrient associated with the foods we consider healthy such as whole grains, legumes, nuts and seeds, it can be frustrating and confusing. After all, these foods are supposed to be some of the most nutrient rich foods on the planet. Even so, most will agree that too much of any good thing will eventually produce negative consequences, regardless of whether we are speaking about food or something else. For this reason, some experts speculate that one of the roles of antinutrients is to prevent the tendency to eat the same food(s) all the time and help us to instinctively know when other nutrients are needed. After all, variety is one of the most important aspects of a healthy diet.
Antinutrients can be defined as either natural or synthetic "toxic" compounds that prevent the absorption of nutrients such as iron, zinc, magnesium, copper and calcium. This doesn’t present a huge problem for most people unless the same antinutrient foods are consumed on a regular basis, which can lead to malnutrition, digestive system/gut problems and other chronic health conditions. Even though antinutrients can have a negative impact on health, they also serve a valuable purpose of protecting the plants against invaders (insects, bacteria, fungus, etc.) and ensuring that the seeds sprout and reproduce properly, instead of being eaten by animals.
Although there are many, three of the most commonly discussed antinutrients are phytates/phytic acid, oxalates/oxalic acid, and goitrogens.
Found in whole grains, nuts, seeds and legumes, phytates (more commonly referred to as phytic acid), can prevent the uptake of all of the previously mentioned nutrients and especially zinc, essential for the optimal functioning of the brain and nervous system. Even though there are preparation techniques to reduce or neutralize phytates, which we’ll discuss in more depth later, soy (a legume with one of the highest phytate content) does not respond well to these techniques and is best eaten only in its fermented form or with meat. In addition to mineral deficiencies, phytates most commonly contribute to digestive problems.
Found in dark-green leafy vegetables such as spinach, kale and swiss chard, oxalates can lead to the development of crystals in the kidneys, bladder, thyroid tissue, heart and even bone. Experts suggest reducing the amount of oxalate foods in the diet to prevent kidney stones from forming, the most common problem related to oxalates. However, others say that as long as you are eating a balanced diet with healthy levels of calcium, there is no need to reduce the amount of healthy greens you are eating (although the daily consumption of spinach is not recommended). Calcium binds to the oxalates and removes them through the bowels before they are filtered through the kidneys. Oxalates are also found in soy, wheat, nuts, beer, beets, chocolate, rhubarb, and strawberries.
Found primarily in soy and cruciferous vegetables (broccoli, cauliflower, brussel sprouts, cabbage, etc.), goitrogens have been most associated with thyroid health. This is because the isoflavins (soy) and isothiocyonates (cruciferous vegetables) can reduce thyroid function by blocking the activity of and enzyme called thyroid peroxidase, which is necessary for adding iodine atoms to thyroid hormones. Although much more problematic with the excess consumption of soy or for those with a preexisting thyroid condition, if prepared correctly, goitrogen content can be reduced significantly to prevent health problems. Goitrogens are also found in millet, peaches, peanuts, strawberries, spinach and radishes.
Some of the other antinutrients include tannins, lectins, cyanide, purines, lipase, amylase, gluten, glycoalkaloids, saponins and enzyme inhibitors.
As most of the antinutrient containing plant foods offer benefits that far outweigh their risks, my recommendation would be to not avoid them unless you have a specific condition that may be worsened by their consumption. As long as you aren’t consuming any one food in excess and preparing your foods properly, you shouldn’t experience any side effects related to the antinutrients.
Proper preparation techniques include soaking, sprouting, fermenting and cooking in order to improve digestion and neutralize the antinutrients. There are many resources online that explain in detail soaking and sprouting times for individual foods. Once you get in the habit, properly preparing your food should become a mindless part of a healthy diet.
 (n.d.) Retrieved from http://www.ivy-rose.co.uk/HumanBiology/Nutrition/What_is_an_Anti-Nutrient.php  Palmer, S. (2011, July). Nutritional anomalymight antinutrients offer some benefits? Retrieved from http://www.todaysdietitian.com/newarchives/070111p54.shtml
 Fallon, S. (n.d.). Newest research on why you should avoid soy. Retrieved from http://www.mercola.com/article/soy/avoid_soy.htm  Shaw, W. (2010, March 26). The role of oxalates in autism and chronic disorders. Retrieved from http://www.westonaprice.org/food-features/the-role-of-oxalates-in-autism-and-chronic-disorders
 Jockers, D. (2011, March 8). Prevent kidney stones. Retrieved from http://www.naturalnews.com/031618_kidney_stones_prevention.html  (n.d.) Retrieved from http://www.whfoods.com/genpage.php?tname=george&dbid=47
Kara wrote for HealthCentral as a patient expert for Food & Nutrition.