Kale vs. Spinach: Is One Better Than the Other?

You know that both are healthy, but you’re also curious: when it comes to kale vs. spinach, does one come out better than the other? Healthier? More nutritious? Read on to find out what makes each of these dark, leafy greens unique, and which (if either of them) comes out on top.

Kale vs. spinach—which is healthier?

All Hail Kale: Kale Nutrition Facts

Let’s start with what makes kale so special. Kale has been around since the 17th century as a crop, but it gained popularity during World War II to help combat malnourishment during times of food scarcity.

Nowadays kale is considered a superfood with many different varieties (lacinato kale aka dinosaur kale, red Russian kale, curly kale and the deeply purple redbor kale) and can be found in the form of kale chips, baked into breads, blended into smoothies, and peppered into salads.

Kale is full of vitamin A, vitamin C, calcium, folate, and fiber. According to the USDA, these are the levels of nutrients you can expect from just 1 cup of raw kale.

  • Calories: 7
  • Protein: 0.61 grams
  • Fat: 0.31 grams
  • Carbohydrates: 0.93 grams
  • Fiber: 0.9 grams
  • Sugar: 0.21 grams
  • Calcium: 53 milligrams
  • Vitamin A: 1011 IU (International Unit)
  • Vitamin C: 19.6 milligrams
  • Vitamin K: 81.8 micrograms
  • Folate: 13 micrograms

If you’ve ever wondered does kale have protein, it does (surprise!), and if you’re still wondering is kale good for you, it most certainly is! However, is it better for you than spinach? Check out the nutritional content of spinach to find out.

The Splendid Spinach: Spinach Nutrition Facts

Much like kale, a single cup of spinach has only 7 calories, but it meets half the daily requirement of vitamin A and has twice the daily recommended value of vitamin K, a lot more than kale. Vitamin K is important for bone health, blood function, and tissue growth in the body. Spinach is also higher in folate, though lower in the antioxidant vitamin C. Again, the following numbers are sourced from the USDA‘s nutrition information for 1 cup of uncooked spinach.

  • Calories: 7
  • Protein: 0.86 grams
  • Fat: 0.12 grams
  • Carbohydrates: 1.09 grams
  • Fiber: 0.7 grams
  • Sugar: 0.13 grams
  • Calcium: 30 milligrams
  • Vitamin A: 2813 IU
  • Vitamin C: 8.4 milligrams
  • Vitamin K: 144.9 micrograms
  • Folate: 58 micrograms

Spinach is higher in some nutrients than others, but does that mean that it’s always got kale beat? Read on to find out how these two green leafy vegetables compare.

The Showdown: Kale vs. Spinach

The health benefits of both kale and spinach are impressive, and either one can bring you the nutritional content you may have come to expect from eating dark green vegetables like collard greens, Swiss chard, and broccoli greens. If you see either spinach or kale on your plate, you know you’re in for some healthy eating, but let’s talk about their differences and get into the nitty-gritty of what separates these otherwise similar veggies.

Nutritional Similarities and Differences

Though often considered interchangeable, especially in recipes, kale and spinach actually hail from totally different plant families. There are many distinctions that set them apart from one another, but let’s begin with their similarities.

The Similarities Between Kale and Spinach

Kale and spinach are both highly nutritious while being low in calories, leading to increased chances of healthy, sustainable weight loss. Here are the other benefits they can each boast about.

Vitamin Content

Both vegetables are high in vitamin K, which is important in bone formation and blood clotting. Spinach and kale are each good sources of vitamin C, which helps prevent disease by supporting immune function. The rest of their antioxidant content also prevents oxidative damage to your cells, one of the earliest steps in preventing chronic diseases. Both of these greens contain the micronutrients riboflavin, calcium, and vitamin A, as well as helpings of fiber for digestive health.

Heart Health

Both kale and spinach have been shown clinically to improve risk factors for heart disease like high cholesterol and high blood pressure. In one study over a period of 12 weeks, 32 men with high cholesterol who drank kale juice with their meals improved not only their antioxidant status, but also their cholesterol levels.

Likewise a study with 27 participants eating spinach soup (9 ounces of spinach per serving) over a 1-week period improved their blood pressure by significantly reducing systolic and diastolic blood pressure. That effect was attributed to the dietary nitrates in spinach, compounds that help increase blood flow.

Cancer-Fighting Properties

Both of these vegetables contain anti-cancer compounds that have been shown to decrease the spread and growth of cancer cells in laboratory and animal studies.

The Differences Between Kale and Spinach

Now for the contrasting differences between spinach and kale, plus some potential downsides to these otherwise healthy vegetables.

Vitamin Disparities

Kale contains more than twice the level of vitamin C, a powerful antioxidant that’s been shown to prevent and help treat the common cold. Spinach has significantly more vitamin A, vitamin K, and folate.

Spinach Is High in Oxalate

There are high amounts of dietary oxalate in spinach, a compound that binds to calcium in the body and prevents its absorption in the gut. Consuming oxalate-rich foods also increases the amount of oxalate excreted through your urine, which could then lead to the development of calcium oxalate kidney stones.

Though there are other types of kidney stones, researchers estimate that 80% of them are made of calcium oxalate deposits, meaning of course that those who are at a high risk of kidney stones are advised to avoid foods high in oxalate, which includes spinach. If you’re concerned nonetheless, boiling spinach has been found to reduce its dietary oxalate concentration by up to 87%.

Kale May Contain Goitrin

Cruciferous vegetables like kale contain goitrin, a compound that has the potential to decrease the body’s uptake of iodine and thus interfere in proper thyroid function and hormone production. Any disruption in thyroid function can disturb your metabolism and cause symptoms such as sensitivity to cold, fatigue, and dangerous and unwanted weight fluctuations. While most goitrogen-rich foods eaten in moderation are not likely to cause any issues for most healthy people, anyone with a history of thyroid issues may be sensitive enough to the influence of goitrin to want to avoid these foods.

For those concerned, both human and animal studies have shown that eating Brussels sprouts and broccoli sprouts did not affect thyroid hormone levels or thyroid function as other cruciferous vegetables did, results which suggest that they are safer to eat for those with thyroid concerns.

The affect of cruciferous vegetables on the thyroid seem to be most pronounced in women with a low iodine intake. Cooking your cruciferous vegetables, much like with spinach’s oxalate content, helps deactivate the enzyme responsible for goitrin release. Upping one’s iodine consumption might also make the difference by helping to neutralize the influence of goitrin.

Long Story Short: Is One Healthier Than the Other?

The differences between kale and spinach in the end are rather small. They both contain health benefits and nutritional content far superior to many other foods and vegetables, and such nutrient-rich foods are a wise inclusion to any healthy, well-rounded diet. Is it fair to say one is better than the other though? Not really.

What we can say is your best bet is to try incorporating a variety of spinach, kale, and other leafy green vegetables like bok choy, collard greens, Swiss chard, and romaine lettuce in your diet regularly. Not only do they each bring unique health benefits to the dinner table, but they can also lend a variety of texture and taste to your tongue. Simple ways to increase your intake of these valuable vegetables include:

  • Adding spinach and/or kale to a mixed green salad
  • Using kale or spinach as a topping instead of pale lettuce, like on your sandwich, shredded over tacos, layered into casseroles, or simmered into your pasta sauce
  • Sautéing spinach or kale with tasty oils and spices (like extra virgin olive oil and garlic) to include as a green side at dinner
  • Chopping these and other greens together with breakfast foods like eggs—breakfast is the one daily meal most likely to be lacking in vegetables, and you can fix that very easily by including some dark, leafy greens
  • Blending up a green smoothie with spinach, kale, both, or more, plus other fruits and healthy ingredients to get the best of everything

The Great Green Debate

The bottom line is that the difference between spinach and kale, though present, isn’t enough to say you should ditch one and stick with the other. Their benefits are excellent, their downsides are mild (if they’re relevant to you at all) and can be easily neutralized by cooking these leafy green powerhouses. It’s almost impossible to choose between these two, and the best part of all: you don’t have to! Mix them up and fix them up for breakfast, lunch, or dinner, and enjoy!

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