Kale is (almost) everyone’s leafy green sweetheart, and it’s easy to see why. It’s anti-inflammatory, has been shown to help protect against both heart disease and cancer, and is packed with digestion-boosting fiber, as well as plenty of vitamin C, calcium, and vision-benefiting lutein. But as often as we may sing the praises of this popular leafy green, going down a rabbit hole regarding the benefits of kale might make you question: can you eat kale raw? That’s because the leafy green in its raw state has some potential “anti-nutrients” that have gotten a bad rap in wellness circles.
Experts in This Article
registered dietitian and mindful eating coach
co-host and co-creator of the Happy Eating podcast
To put it plainly, kale undoubtedly gets the green (pun intended) light for most folks. But, for others, there may be a few instances where you’re better off swapping kale for another one of your favorite healthy leafy greens. Ahead, we hear from two registered dietitians about the pros and cons of eating raw kale and how it may impact you.
Is kale safe to eat raw?
Raw kale is totally safe and healthy for most adults to eat, provided that it’s washed! You can eat kale raw in a salad, blended up into smoothies, and more.
However, kale tends to be tough and fibrous. If you plan to eat it raw, you’ll want to prepare it well. Be sure to cut or tear out the big thick stems (you can roast those separately or compost them), chop or tear up the leaves into bite-sized pieces, and then massage your kale with a little oil and salt in a bowl until it darkens in color and becomes softer in your hands.
When should you not eat kale?
Nutrition experts say there are some people who should limit or avoid eating raw kale because of pre-existing health conditions. Here is who should be mindful about eating raw kale:
1. If you have thyroid issues
Raw kale is made up of a compound that can affect one’s metabolism in both good and potentially “bad” ways. “Kale gets its super healthy reputation in part because of compounds called glucosinolates1,” says Brierley Horton, RD. (Found in all cruciferous vegetables, glucosinolates are the subject of intense research centered on cancer prevention2.) However, Horton notes that it’s this exact compound that can also potentially pose a problem for some folks. Some glucosinolates can decrease thyroid hormone production3, which is essential for regulating your metabolism.
For most people, the negative effect of glucosinolates is minimal. But if you have hypothyroidism, an underactive thyroid gland, you’ll want to be cautious about your intake. Thankfully, these compounds are only present in raw kale. So sauté, roast, or steam your kale to enjoy all the flavor and health benefits, without risk to your thyroid.
2. If you tend to get kidney stones
“Another population that might be wary of regular raw kale consumption would be those with kidney stones who have been told to follow an oxalate-restricted diet,” says dietitian Beth Basham, RD, LD. “Oxalates are a compound 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,” she says.
Again, if you haven’t had kidney stones, this isn’t something to worry about. But if you do get kidney stones, you’ll have to be really mindful about your kale intake, whether it’s raw or cooked. “Oxalates 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,” Basham says.
3. If you struggle to eat enough fiber
Kale is an extremely fibrous vegetable packed with boatloads of fiber per serving. Although this is typically good news for gut health, having a little too much fiber at once can lead to digestive discomfort. As such, consuming raw kale in moderation can be the best solution if it’s tough on your digestion.
Is it better to eat kale raw or cooked?
Cooked vs. raw kale differ ever so slightly from a nutritional standpoint—so it’s really about your particular health or nutrition needs as well as your taste preferences.
On the one hand, cooked kale may have fewer antioxidants, vitamins, and minerals, but can be beneficial for those with thyroid concerns. (And it tastes so good!) Raw kale may be harder to digest, but higher in nutrients. Ultimately, either way to include kale in your daily routine that meshes best with your lifestyle and health is the best way to go.
Healthy tips to eat kale and enjoy it
1. Cook it
Worried about raw kale’s potential impact on your thyroid health? No problem, just 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. (Keep in mind that steaming raw kale won’t be as effective in lowering the glucosinolate content as the other aforementioned cooking techniques.)
2. Pair it with healthy fats
Basham also recommends combining kale with healthy fats to give it an extra nutrient 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. Make more than just green smoothies
Broaden your kale horizons and try making different things than just green smoothies with the vegetable. “Consider ditching the daily green smoothies and eating a normal, whole foods meal,” Basham suggests. “They’re enjoyable from time to time. But drinking more than one daily probably provides little benefit and may pose some risks,” Basham says. (Think: accidentally eating too much sugar, not getting a filling meal, etc.) “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,” she says.
4. Massage it
Indeed, massaging kale isn’t just a chef-inspired concept or tedious cooking step. It can also help make kale a bit more digestible and easier on the gut. This is because rubbing the leaves can help tenderize them, transforming them from a tough, fibrous plant to a more digestible, easier-to-chew star ingredient in your favorite kale salad recipe.
Bottom line
Don’t worry, you probably don’t need to rethink those gigantic raw kale salads for lunch anytime in the near future. “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,” she says.
That said, whether you’re someone who’s affected by the raw greens or not it’s best to chat with a medical professional to come up with a game plan appropriate for your health concerns and goals.
How to make a tasty kale salad with a honey lemon vinaigrette:
Prieto, M A et al. “Glucosinolates: Molecular structure, breakdown, genetic, bioavailability, properties and healthy and adverse effects.” Advances in food and nutrition research vol. 90 (2019): 305-350. doi:10.1016/bs.afnr.2019.02.008
↩︎Soundararajan, Prabhakaran, and Jung Sun Kim. “Anti-Carcinogenic Glucosinolates in Cruciferous Vegetables and Their Antagonistic Effects on Prevention of Cancers.” Molecules (Basel, Switzerland) vol. 23,11 2983. 15 Nov. 2018, doi:10.3390/molecules23112983
↩︎Felker, Peter et al. “Concentrations of thiocyanate and goitrin in human plasma, their precursor concentrations in brassica vegetables, and associated potential risk for hypothyroidism.” Nutrition reviews vol. 74,4 (2016): 248-58. doi:10.1093/nutrit/nuv110
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