Some of the latest buzz in diet blogs and books centers around something called antinutrients. The name sounds incredibly ominous, but these compounds may be getting an undeserved bad rap, say nutrition experts.
Here's the scoop on what they are and whether you should be concerned about them in your diet.
What are antinutrients?
Antinutrients are plant-based compounds found in an array of foods — including beans, whole grains, nuts, seeds, vegetables and leafy greens — that reduce the body’s ability to absorb or use essential vitamins and nutrients.
According to the Harvard School of Public Health, some of the most common categories of antinutrients include:
Glucosinolates — Found in cruciferous vegetables like broccoli, Brussels sprouts, cabbage, they can cause issues with iodine absorption.
Lectins — These are found in legumes (beans, peanuts, soybeans) and whole grains and may hinder the absorption of calcium, iron, phosphorous and zinc.
Oxalates — Found in green leafy vegetables and tea, they interfere with the body's ability to absorb calcium.
Phytates — Phytic acid is in legumes, seeds, whole grains, and nuts and can cause issues with calcium, iron and zinc.
Saponins — Found in legumes and whole grains, saponins can interfere with the absorption of nutrients.
Tannins — These are in tea, coffee and legumes and can cause issues with iron.
Are antinutrients harmful?
Although they have the ability to stop your body from absorbing things like calcium, iron, zinc and other vital nutrients, antinutrients aren't a concern for the average person with a healthy diet, say nutrition experts.
"If you eat a varied, nutrient-dense, balanced diet, for the vast majority of people, there’s no need to worry about antinutrients," registered dietitian Malina Linkas Malkani, spokesperson for the Academy of Nutrition and Dietetics, tells MNN. "They are primarily found in foods that have enormous, documented health benefits, like grains, vegetables and beans. For the vast majority of people, the benefits of nutrient-dense whole foods outweigh the concerns of antinutrients."
There are some exceptions. If you have certain health conditions, then you may be more susceptible to problems with antinutrients. For example, if you have an underlying thyroid disorder or iodine deficiency, you might be more likely to have problems with the glucosinolates found in cruciferous vegetables. Similarly, if you are prone to calcium oxylate kidney stones, then it would be smart to limit high-oxylate foods like green leafy vegetables, Malkani suggests.
Antinutrients can be problematic in very specific dietary situations.
"They are typically dangerous only when you have a unique situation usually created by very limited or very poor diet," Sarah L. Ash, a professor of nutrition at North Carolina State University, tells MNN.
She gives the example of case studies in Egypt in the 1960s when young men experienced problems with sexual maturation. It turns out they had zinc deficiencies due to high levels of phytates because of certain breads they were eating.
"If your diet is poor or limited, then you are at risk for having too much of a bad thing or not enough of a good thing," Ash says. "But that is just so unlikely unless you are following some extreme diet."
Where the buzz came from
Although the term has been around for a while, the recent interest in antinutrients likely stems from the 2017 book "The Plant Paradox" by cardiac surgeon Steven Gundry, M.D. In it, Gundry claims that lectins "incite a kind of chemical warfare in our bodies, causing inflammatory reactions that can lead to weight gain and serious health conditions." It warns of the "hidden dangers lurking in your salad bowl" and suggests switching from brown rice to white rice and avoiding tomatoes, wheat, beans and so many other foods that traditionally have been considered very healthy.
"The funny thing about lectins is that they are found in greater quantity in things we really don’t eat like raw beans and raw grains," says Malkani. "There are things you can do to foods — like boiling them, soaking them — then you can still get the benefits of these incredibly healthy nutrition-dense foods without the concerns. Lectins have a lot of benefits and negatives, which is why people get confused."
Some celebrities such as singer Kelly Clarkson raved about the book and helped put lectins and antinutrients on popular radar, and other books and websites began disparaging the compounds.
But it's too simplistic to characterize antinutrients as "good" or "bad." Some of them have beneficial effects. Some glucosinolates in cruciferous vegetables may have anticarcinogenic effects, for example, says Ash.
"We try to turn eating into a science and it really doesn’t work well because food is so complex," she says. "Plants may contain things that are good for us. They may contain things that are less good for us. Trying to look at one without looking at the other is problematic. If you eat a variety of things in moderation, then none of it matters."
"With people talking about the danger of antinutrients there's the danger of vilifying a single food or nutrient without evidence backing up that claim," she says. "Antinutrients have both positive and negative effects and we can't look at them in a black or white way. We have to look at both sides and weigh them."