Ask the RD: Are Beans and Whole Grains Good for You?
Question: Are there really “antinutrients” in beans and whole grains? Aren’t beans and whole grains good for you?
Answer: The answer is yes, to both questions. Antinutrients are substances in food that interfere with the availability or absorbability of nutrients. Many substances are considered antinutrients. Protease inhibitors in soybeans can interfere with protein digestion; glucosinolates in cruciferous vegetables like Brussels sprouts and cauliflower can interfere with iodine absorption (Suliburska & Krejpcio 2014); even fiber can be an antinutrient because it may get in the way of mineral absorption. Phytic acid—found in whole grains, nuts and legumes—binds with calcium, iron and zinc. Oxalic acid in spinach also interferes with calcium absorption. Polyphenols, including tannins in red wine and tea, inhibit iron and zinc absorption.
It’s fascinating that some of the same components that give plant foods their health benefits—components like fiber and polyphenols—can also be antinutrients. So the question becomes, should you try to avoid these substances? The answer is definitely no. The overwhelming evidence is that a plant-based diet is good for your health, even if plants that contain antinutrients are included.
Cooking whole grains, beans and vegetables reduces the impact of antinutrients. Sprouting grains and legumes, as in mung bean sprouts, reduces phytic acid (Gupta, Gangoliya & Singh 2015). Fermenting also reduces antinutrients; think fermented vegetables like kimchi and sauerkraut, or fermented soy foods like miso and tempeh. In fermented foods, microbes have already done some of the work of digestion, which improves the availability of a variety of nutrients, including protein, iron, calcium and B vitamins (Sheers et al. 2016; Landete et al. 2015). Antinutrients in vegetables, whole grains, legumes and nuts are a concern only when a person’s diet is very limited in terms of calories and/or variety (Hunt 2003), or when the diet is composed exclusively of uncooked plant foods.
There’s no need to be concerned about antinutrients as long as you keep eating beans, whole grains and other plant foods in a wide variety of forms, including sprouted, fermented, raw and cooked.
Gupta, R.K., Gangoliya, S.S., & Singh, N.K. 2015. Reduction of phytic acid and enhancement of bioavailability of micronutrients in food grains. Journal of Food Science and Technology, 52 (2), 676–84.
Hunt, J.R. 2003. Bioavailability of iron, zinc, and other trace minerals from vegetarian diets. American Journal of Clinical Nutrition, 78 , 633S–39S.
Landete, J.M., et al. 2015. Effect of soaking and fermentation on content of phenolic compounds of soybean (Glycene max cv. Merit) and mung beans (Vigna radiata [L] Wilczek). International Journal of Food Sciences and Nutrition, 66 , 203–209.
Scheers, N., et al. 2016. Increased iron bioavailability from lactic-fermented vegetables is likely an effect of promoting the formation of ferric iron (Fe3+). European Journal of Nutrition, 55, 373–82.
Suliburska, J., & Krejpcio, Z. 2014. Evaluation of the content and bioaccessibility of iron, zinc, calcium and magnesium from groats, rice, leguminous grains and nuts. Journal of Food Science and Technology, 51 , 589–94.