Kale and spinach are dark leafy greens that offer an abundance of vitamins, as well as potentially beneficial plant phytochemicals.

People comparing kale with spinach will find that both offer health benefits and also carry some risks. There is no clear winner, but a person’s health needs may dictate which is better for them.

Keep reading to learn more about the health benefits of kale and spinach.

Close up of person carrying kale.Share on Pinterest
Rawpixel/Getty Images

One hundred grams (g) of raw kale contains:

  • 43 calories
  • 2.92 g protein
  • 1.49 g fat
  • 4.42 g carbohydrates
  • 4.1 g fiber
  • 0.8 g sugar
  • 254 milligrams (mg) calcium
  • 241 micrograms (mcg) vitamin A
  • 1.6 mg iron
  • 53 mg sodium
  • 93.4 mg vitamin C
  • 62 mcg folate
  • 390 mcg vitamin K

Cooking kale with salt or oil may change the nutritional value slightly, as it may change the amounts of sodium or fat.

Kale is rich in the phytochemicals zeaxanthin and lutein. These nutrients play a key role in eye health and may reduce the risk of certain forms of blindness.

Traditional medicine practitioners use the phytochemicals in kale to heal various ailments.

Scientific research is emerging that supports some of these claims. For example, a 2008 study found that drinking kale juice could improve coronary artery disease risk factors in men with high cholesterol. Kale juice helped lower cholesterol.

A few studies, some on animals, have found that quercetin, a chemical prevalent in kale, offers heart health benefits, most notably lowering high blood pressure.

Kale is high in antioxidants, such as vitamin C, which may help fight oxidative damage to the body. Oxidative damage plays a role in many illnesses, including cancer, heart disease, and diabetes.

Its high fiber content can help improve digestion and ease constipation. Some research also suggests that fiber intake may correlate with a lower risk of heart disease and cancer.

Kale is relatively high in protein compared with most other fruits and vegetables. People who eat plant-based diets may struggle to get enough protein.

Kale contains high quantities of folate, a nutrient vital to the development of healthy pregnancies. Folic acid, a folate derivative, may help prevent neurological defects in a developing fetus. The Centers for Disease Control and Prevention (CDC) recommend a person takes 400 mcg of folic acid daily during their pregnancy.

Kale is high in calcium, which may help promote healthy bones and reduce the risk of osteoporosis.

One hundred grams of raw spinach contains:

  • 23 calories
  • 2.86 g protein
  • 0.39 g fat
  • 3.63 g carbohydrates
  • 2.2 g fiber
  • 0.42 g sugar
  • 99 mg calcium
  • 2.71 mg iron
  • 79 mg sodium
  • 28.1 mg vitamin C
  • 469 mcg vitamin A
  • 194 mcg folate
  • 483 mcg vitamin K

Spinach contains relatively high quantities of protein compared with other vegetables, though it is slightly lower in protein than kale. It also offers beneficial fiber, but at about half the level of kale. A 2019 study suggests that a diet high in fiber can lower heart disease risk in people with high blood pressure and type 2 diabetes.

Like kale, spinach is rich in phytochemicals and bioactives, which have a long history in alternative and traditional healing. The thylakoids and glycolipids in spinach may lower the risk of cancer and obesity, and support better blood sugar control.

Spinach contains more than double the amount of folate as kale, making it an ideal food during pregnancy.

It is relatively high in bone-protecting calcium, though it contains less than kale. It also offers a wide variety of antioxidants, potentially helping lower the risk of heart disease and age-related cellular damage.

Spinach is also an imperfect food. Leafy greens often contribute to Escherichia coli (E. coli) outbreaks, and spinach is a common culprit. In 2006, researchers traced about 80% of E. coli cases in a major outbreak to contaminated spinach. In a 2013 analysis, 6.6% of farmed spinach samples tested positive for the bacteria.

Kale and spinach are a healthier alternative to less nutritionally dense, high-water lettuces such as iceberg and romaine.

Some other dark leafy greens that offer a similar nutritional profile to kale and spinach include:

To maximize health benefits, try eating a salad mixed with several greens, or try a different green each day.

Spinach, kale, and other dark leafy greens offer similar nutritional benefits, including a high dose of beneficial plant chemicals and fiber.

The individual benefits vary from person to person, depending on their health goals.

It is important to choose leafy greens that a person enjoys eating, since making vegetables a daily part of the diet offers more benefits.