Here’s what you need to know about kale, including its nutritional facts, health benefits, health risks, and more.
Defining Kale: What Exactly Is This Green, Leafy Veggie?
Kale is a cruciferous vegetable in the same family as cabbage, cauliflower, broccoli, and collard greens. It is easily distinguishable from its family members with its purple and green leaves. As a winter vegetable, kale is a delicious choice in the cold months when other cruciferous options are less available. As a bonus, if you wait to buy kale till after a heavy frost, you may notice a sweeter taste. (1) This popular vegetable has been around for centuries, starting off as a common vegetable in Europe. Colonists brought it to North America in the 16th century. (2) One cup of cooked kale has about 42 calories, 106 grams (g) of water, and 1.4 g of fat. Other nutritional facts for kale include: (3)
5 g of fiber (18 percent daily value [DV])3 g of protein (6 percent DV)172 retinol activity equivalents (RAE) of vitamin A (19 percent DV)21 milligrams (mg) of vitamin C (23 percent DV)493 micrograms (mcg) of vitamin K (410 percent DV)177 mg of calcium (14 percent DV)30 mg of magnesium (7 percent DV)170 mg of potassium (4 percent DV)
Helps Prevent Cancer
Kale contains cancer-fighting carotenoids, which are antioxidants that protect cell DNA from damage caused by free radicals. Such damage can cause cancer. Vitamin C in kale can also reduce inflammation, strengthen the immune system, and fight oxidative stress, which can help prevent cancer and other illnesses like the common cold and the flu. The recommended daily intake of vitamin C is 90 mg for adults, which is about 4.25 cups of cooked kale. (6)
Aids in Protecting Eyesight
Kale also contains the vitamins lutein and zeaxanthin, which contribute to healthy eye cells and help lower the risk of age-related macular degeneration. (7)
Promotes Healthy Blood Clotting
Vitamin K plays a role in healthy blood clotting, and people with a deficiency may experience slow clotting time. This can lead to excess bleeding. (8) Vitamin K also improves bone density and supports strong bones, reducing the risk of fractures. The recommended daily dose of vitamin K for women older than 19 is 90 mcg a day, and men should have 120 mcg a day. One cup of cooked kale contains 493 mcg. (3,8)
Helps With Weight Loss
Because kale is low in calories and high in water, it’s an excellent food for weight loss. (3) It also contains fiber, which will help you feel full longer and prevent overeating. There are no guidelines for how much kale to eat for weight loss. But because of its low calorie count, you can eat kale to your satisfaction and keep your calories per meal on the low end. Kale’s high water content may also increase urination and help your body flush out excess water weight. Vitamin A (retinol) is essential for healthy cell growth, and a vitamin A deficiency often leads to dry skin and acne. Although vitamin A is measured in IU, it has micrograms of retinol activity equivalents (RAE). The recommended daily amount of RAE is 900 mcg for adult men and 700 mcg for adult women. (9) One cup of cooked kale contains the equivalent of 172 mcg of RAE of vitamin A. (3)
Contributes to Healthy Blood Sugar Levels
Manganese is a trace mineral in kale that may decrease insulin resistance, the hallmark of type 2 diabetes, and help people with type 2 diabetes maintain healthy blood sugar levels. It’s also believed that a deficiency of this mineral may predispose a person to diabetes. (10) The adequate intake (AI) of manganese for adults is 2.3 mg for men and 1.8 mg for women. One cup of cooked kale provides 0.64 mg, so you need to consume only between 2.8 and 3.6 cups daily. (3) You can include both on your plate or alternate between the two for variety. But if you’re curious as to whether one is better than the other, here’s how these two veggies stack up.
Vitamin A
Both veggies are great sources of vitamin A, with kale providing 172 RAE per cooked cup. But if you’re looking for the biggest vitamin A punch per serving, you’re better off with cooked spinach, which contains 943 RAE per cup. (3,12)
Fiber and Protein
Spinach also comes out on top as far as protein goes. One cup of cooked spinach boasts about 5.3 g of protein. You only get 3.5 g of protein with kale. However, kale does have slightly more fiber than spinach, 4.7 g and 4.3 g, respectively. (3,12)
Vitamin C and Vitamin K
While kale lags behind spinach with regard to protein, it does contain 21 mg of vitamin C, whereas spinach has 17.6 mg. Spinach, on the other hand, doubles kale’s amount of vitamin K, with 889 mcg versus kale’s 493 mcg. (3,12)
Calories
Spinach also wins by a nose if you’re particularly interested in calorie reduction. It has about 41 calories per cup, whereas kale has about 42 per cup. (3,12) Curly Kale This is the most common type of kale, and you can recognize it by its curly or ruffled edges. It’s available in different colors, including purple, dark green, and bright green. Red Kale Red kale has a slightly different appearance from curly kale. Its leaves may appear deep red or grayish green. Lacinato/Dinosaur Kale This type of kale has a deeper color, with leaves that are a dark bluish-green. This type of kale is more tender than curly or red kale, making it easier to eat raw. Baby Kale With its young tender leaves, this kale is also a good choice for a raw, healthy snack. Purple Flowering Kale This kale has a bitter taste and closely resembles cabbage leaves. White Flowering Kale Add this kale to the menu if you prefer a peppery taste in your soups and side dishes. Because kale is a source of vitamin K, which promotes healthy blood clotting, people who take blood thinners should speak with their doctor to see how much they can safely eat. Eating too much kale may interfere with the effectiveness of these medications, especially if the amount you eat from day to day varies greatly. (14) Eating this vegetable in large amounts may also cause an enlarged thyroid. Kale contains thiocyanate, and in large doses, this substance can trigger an iodine deficiency. Iodine contributes to healthy thyroid function, and a deficiency may lead to hypothyroidism. (15) There are no set guidelines on how much kale to eat with these conditions. Eating small amounts should be okay. Still, talk to your doctor before adding more kale to your diet if you have any of the above health conditions. (15) You can sauté it in oil, garlic, or butter, or add a handful to soups, salads, and smoothies — or try these 10 creative ideas for when kale is on the menu, including BBQ Salmon and Kale Tacos and Kale Pesto Naan Pizza. Hearty Chicken Soup With Fiber-Rich Kale is also delicious.
