Stressing About “Anti-Nutrients” Might Sabotage Your Healthy Diet

Photo: Getty Images/Dean Mitchell
Sometimes when I'm scanning a food label, I feel like I need a dietitian on speed dial who can tell me exactly what I should eat and what to avoid. Lately, a certain compound commonly found in foods like spinach, apples, oat milk, and coffee is causing causing widespread confusion.

"Anti-nutrients are found in foods that block the absorption of nutrients like protein, carbohydrates, fats, minerals, and vitamins," says registered dietitian and You Versus Food host Tracy Lockwood Beckerman, RD. "This label assumes that these foods are harmful to the human body, when in fact many of our most nutritious foods—vegetables, fruits—are full of anti-nutrients. These foods are what you should be eating!"

In other words, the prefix "anti-" carries a negative connotation, giving anti-nutrients an undeserved bad reputation.

Under the umbrella of anti-nutrients are specific compounds found in everything from nuts to cucumbers to french fries and beyond. More specifically, anti-nutrients include lectins (which interfere with absorption of calcium, iron, phosphorus, and zinc), phytates (which block iron, zinc, magnesium and calcium), tannins (which halt the absorption of iron), and protease inhibitors (which break down protein), among others.

"This label assumes that these foods are harmful to the human body, when in fact many of our most nutritious foods—vegetables, fruits—are full of anti-nutrients." —Tracy Lockwood Beckerman, RD

At face value, all that info kind of sounds like the side effects listed in a pharmaceutical commercial. There's a problem with thinking about these foods in such polarizing manner though: There's a whole lot of nutritional nuance that gets lost when we do.

"The beneficial nutrients of plant-based foods far outweigh the negative effects," says Brittany Michels, RD, a dietitian for The Vitamin Shoppe. Yes, Brussels sprouts contain glucosinolates, which prevent the absorption of iodine, according to Beckerman. But (but!) they happen to be rich in fiber, folate, and Vitamin K. As with every food you eat, the pros and cons need to be weighed together. That being said, there are certain people who should be wary of anti-nutrients.

"If you are at risk for a mineral deficiency or kidney stones, then these anti-nutrients are 'bad' for you," says Beckerman. Specifically, these folks should ditch foods containing oxalates—like beets and bran flakes—which "bind to calcium or iron and can form crystals which are passed through into urine, creating kidney stones," she explains. If you're anemic or at risk for osteoporosis, you should also avoid anti-nutrients as best you can or take certain precautions in food preparation. Beckerman says that soaking legumes before eating them, fermenting or boiling vegetables, and combining anti-nutrient foods with ones that don't are all countermeasures you can take to limit the power of these compounds.

If you prefer to eat your broccoli raw, know that its nutritional benefits far outweigh the presence of glucosinolates (which are found in the cruciferous vegetables). People may hate on anti-nutrients, but dietitians will tell you to give them a spot on your plate.

These six foods are should rule your diet. And if you're looking for snack ideas, here's what dietitians reach for when hunger strikes. 

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