Is Eating Raw Kale *Actually* Bad for You? Here’s What the Experts Say
As a food that's known for its impressive nutritional profile, there's really no wrong way to use it. Kale has made its way into salads, smoothies, green juices, tacos, pasta dishes, and more. You can even find it in the chip aisle. And while eating as much of the leafy green as possible isn't a problem for most people, a handful may need to watch their intake when eating raw kale. While kale itself is an all-star, one thing that gives it its bright and shiny gold star in the health world is also something that can lead to health issues in certain individuals.
- Beth Basham, MS, RD, LD, registered dietitian and mindful eating coach
- Brierley Horton, MS, RD, co-host and co-creator of the Happy Eating podcast
"Kale gets its super healthy reputation in part because of compounds called glucosinolates," says Brierley Horton, MS, RD. (Found in all cruciferous vegetables, gluconsinolates are the subject of intense research centered on cancer prevention.) "However, it’s that exact same compound that also can pose a problem for your metabolism." Glucosinolates can impact your thyroid, which keeps your metabolism under control. It’s only in raw kale that these compounds are present and problematic. But to really hinder your thyroid you would have to eat a lot. One endocrinologist told me that it would have to be bowls and bowls to really be an issue. That is, unless you have hypothyroidism.
Along with creating some thyroid concerns in some women when eaten in large quantities, Beth Basham, MS, RD, LD, says eating raw kale could also affect another subset of the population: those susceptible to kidney stones.
"Another population that might be weary of regular raw kale consumption would be those with kidney stones who have been told to follow an oxalate-restricted diet," Basham says. "Oxalates are commonly found in foods—included, but not limited to—kale, spinach, beets, and nut butters. Excess consumption of oxalate-containing foods can be problematic for those who are susceptible and may lead to pain and future kidney stone development."
But don't worry, you probably don't need to rethink those gigantic raw kale salads for lunch. "The hype about raw kale is mostly just that. The majority of folks won’t be impacted," Horton says. "And if you have hypothyroidism, raw kale—and other crucifers—aren’t off limits. Your approach then should be consistency. If you’re consistent about how much raw kale you eat, you and your doctor can appropriately titrate your synthroid dosage."
Whether you're someone who's affected by the raw greens or not—something you can chat with your doctor about to be sure—there are some expert-approved ways to reap the benefits, minus these potential health problems.
3 healthy ways to eat kale
1. Cook it
"Glucosinolates are greatly diminished by cooking, so it’s good advice to boil, roast or stew your kale before eating. This is the same for any other cruciferous veggie like broccoli, Brussels sprouts, cabbage, cauliflower, collards, kohlrabi, and bok choy," Basham says. "Oxalates, on the other hand, aren't shown to be affected by cooking, so if you're on an oxalate-restricted diet, you may still need to moderate your intake."
2. Mix things up
Instead of always enjoying kale the same way, Horton says it's a good idea to mix things up. "Don’t always eat it raw or juiced. Roast it, sauté it, or bake it," she says. Basham also recommends pairing kale with healthy fats to give it a boost. "Eating your veggies with fat increases the availability of fat-soluble vitamins D, E, A, and K from the food source—a benefit you don't want to miss out on," she explains. "Lightly sautéing or drizzling your crucifers with coconut oil, ghee, butter, or extra-virgin olive oil are all nourishing ways to accomplish this task."
3. Ditch the liquids
Giving up your beloved smoothies—or at least cutting down on them!—might seem impossible. But doing so could better your health.
"Consider ditching the daily green smoothies and eating a normal, whole foods meal. Will a green smoothie kill you? No. In fact, they're enjoyable from time to time. But drinking more than one daily probably provides little benefit and may pose some risks," Basham says. "There's no current recommendation on the number of green smoothies you can have, but if you can't live without them, limit consumption to three or four times per week if you include raw kale."
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