Comparing Kale vs. Spinach Nutrients

Medically reviewed by Suzanne Fisher, MS, RD, LDN

Leafy greens are among the healthiest foods on the planet, offering benefits for heart health, brain health, and blood sugar control. While there's a great debate over whether spinach or kale is healthier, both are packed with nutrients and plant compounds that benefit your health. This doesn't mean they're the same, though.

In this article, we will examine the nutritional differences between spinach and kale and how they compare in their taste and uses in recipes.

Nutritionally, How Does Kale vs. Spinach Compare?

We often hear kale referred to as a "superfood" because of all its nutrients, but the truth is that it's not necessarily any more special or more nutritious than other leafy greens. For instance, spinach and kale are powerhouse leafy greens rich in various nutrients.

You can't go wrong by including either one or ideally a combination of both, in your diet. Eating leafy greens daily is a nutrition goal we might all strive to achieve. Let's take a closer look at spinach vs. kale nutrition and general daily nutrient recommendations for adults.

"Superfood" is a marketing term used to describe nutrient-dense foods that offer health benefits. There are no standard criteria to deem certain foods "superfoods," but they are generally rich in micro- and macro-nutrients derived from natural sources.

Fiber

Plant foods like leafy greens are the only source of dietary fiber. Fiber is an essential nutrient for feeding your gut microbiome, or the community of good bacteria that live there. It helps support your digestive, heart, and immune health and encourages healthy blood sugar regulation.

The recommended daily amount (RDA) of fiber is 25 grams per day. One cup of raw spinach provides 0.7 grams of dietary fiber, whereas one cup of raw kale contains slightly more, at 0.9 grams of fiber.

Surveys have found that most Americans don't get enough fiber, with an estimated 95% of adults not consuming the minimum recommended daily amount, around 30 grams. Adding spinach and kale to your diet is a great way to help boost fiber intake.

Vitamin K

Vitamin K is an important nutrient for blood clotting or slowing blood flow when you have an injury so that the wound can heal. It also plays a role in supporting bone health along with calcium and vitamin D.

Leafy greens like spinach and kale contain vitamin K1, whereas certain animal products and fermented foods provide vitamin K2.

The RDA of vitamin K is 120 micrograms (mcg) daily. One cup of raw spinach provides 145 micrograms of vitamin K, and you will get 82 micrograms in one cup of raw kale.

Vitamin C

Vitamin C is a water-soluble vitamin and antioxidant which helps protect cells from damage and supports immune health. While it's often attributed to citrus fruits like oranges, vitamin C can also be found in leafy greens.

One cup of raw spinach provides 8.5 of the recommended 80 milligrams (mg) of daily vitamin C, while one cup of raw kale provides 20 milligrams.

Vitamin A

Getting enough vitamin A, specifically 3,000 international units daily, is important for immune function and eye health. Spinach and kale contain compounds called "carotenoids," which our bodies convert to a usable form of vitamin A.

In one cup of spinach, you'll find 2,810 international units (IU) of vitamin A, while there are 1,010 international units of vitamin A in one cup of raw kale.

Calcium

You may think of dairy products when you see the word "calcium," but plenty of plant foods, including spinach and kale, also provide calcium. Adequate calcium consumption supports healthy bones and teeth, nerve communication, and muscle movement.

The recommended daily amount of calcium for adults is 1,300 milligrams (mg). One cup of raw spinach contains 30 milligrams of calcium, and one cup of raw kale has 53 milligrams.

Spinach also contains a plant compound called "oxalate," which can bind to calcium and reduce absorption. Consuming oxalate-rich foods can increase how much oxalate is removed through your urine and promote the formation of calcium-oxalate kidney stones. Generally, this is only a potential concern for people with a history of, or are at a higher risk for, kidney stones.

If you're concerned about kidney stones, opt for kale, a low-oxalate leafy green.

Folate

Folate is a B vitamin best known for its importance in pregnancy to help prevent neural tube defects, like spina bifida, in fetuses. The RDA for folate is 400 micrograms (mcg), and in pregnant people and lactating people, the recommendation increases to 600 micrograms.

Leafy greens like spinach and kale are among the best places to find folate in your diet. One cup of raw spinach provides 58.2 micrograms of folate, whereas one cup of raw kale contains 13 micrograms.

Related:Eating 1 Cup of Green Leafy Vegetables Can Support Heart Health

What About Kale vs. Spinach in Raw vs. Cooked Form?

If you've ever cooked leafy greens, you know how much they shrink from their raw form. A whole box of raw spinach can quickly become a small pile of cooked spinach as it shrinks. But how does cooking affect leafy greens nutritionally?

The primary difference is that you can consume more spinach or kale in their cooked versus raw form simply because there is less volume. This also means you'll get more nutrients per serving in cooked versus raw leafy greens.

However, some water-soluble vitamins can be lost when spinach or kale are cooked using water-heavy methods, such as boiling, or when they come into contact with oil, like sauteing. Research has found that steaming, baking, and microwaving preserve nutrients, antioxidants, and other beneficial plant compounds more than other vegetable cooking methods.

Nutritionally, leafy greens have much to offer regardless of whether they are raw or cooked. Eating raw and cooked spinach and kale in your diet is an excellent way to experiment with different recipes and determine how you enjoy them the most.

Taste-Wise, How Does Kale vs. Spinach Compare?

The spinach and kale benefits list is long, but leafy greens can be an acquired taste for many people, especially if you didn't grow up eating them. While all leafy greens are similar in their raw texture and earthy flavors, each type offers a unique taste.

When it comes to spinach versus kale, spinach tends to have a softer, more buttery, and smooth texture with a mild flavor. Spinach works well raw in salads and sandwiches or as a pizza topping, or cooked and mixed into grain bowls and soups.

Steam it or sauté it in a pan with garlic and avocado oil. For a tropical green beverage, you can also toss spinach into smoothies along with fruit, like blueberries, green apples, and pineapple.

Kale offers a rougher texture that many prefer to soften before adding to salads and sandwiches. Do this by massaging chopped raw kale with olive oil and salt using your hands. Kale can have a slightly bitter flavor than spinach but is also very versatile.

You may wish to remove the inner stem of each leaf before chopping kale since it is tough to chew. Once you remove the stem, chop and add it to salads, casseroles, smoothies, and pasta dishes, or make roasted kale chips in the oven for a healthy snack. You can also sauté kale in a pan with some garlic and olive oil or add it to a breakfast scramble.

Spinach and kale both have a mild, earthy, green flavor that works well in various preparations, whether you want to make them the centerpiece of spinach and kale recipes or use them to boost nutrition in a dish. Experiment with both to determine which you like best and how you prefer to use them in your kitchen.

Summary

Spinach and kale are two of the most widely consumed leafy green vegetables offering numerous health benefits. Both are packed with nutrients like fiber, vitamins, and minerals. Still, there are subtle nutritional differences between them.

Kale provides more calcium and vitamin C per serving than spinach, whereas you will find more folate, vitamin A, and vitamin K in spinach than kale. Per cup, they contain a similar amount of fiber. Both leafy greens are excellent choices to incorporate into your diet, whether you enjoy them raw or cooked, in casseroles, soups, smoothies, salads, or sandwiches.