Nutrition Diet: Which is Healthier, Spinach or Kale?

October 5, 2025 •

4 min read

According to the USDA, Americans should eat several servings of leafy greens per week, but when faced with the choice, many wonder: which is healthier, spinach or kale?. The simple answer is that both are incredibly nutritious superfoods, and the best choice often depends on your specific health goals.

Quick Summary

This nutritional comparison examines spinach and kale's key differences in vitamins, minerals, and other health benefits. The analysis reveals that kale offers more vitamin C and calcium, while spinach contains higher levels of folate, potassium, and iron, though its bioavailability can be low.

Key Points

Nutrient Differences: Kale has more vitamin C and calcium, while spinach is richer in vitamin A, vitamin K, and folate.
Iron Absorption: Spinach contains oxalates that inhibit iron absorption; pairing it with vitamin C can improve this.
Bone Health: Kale is a superior non-dairy source of bioavailable calcium compared to spinach.
Culinary Use: Spinach's tender texture is great for salads and smoothies, while kale's heartiness stands up to cooking in soups and stews.
Healthier Option: Neither is definitively 'healthier'; the best choice depends on your specific nutritional needs and eating a variety of greens is most beneficial.
Digestive Effects: Kale contains more fiber than spinach, but can be harder to digest for some.
Cooking Considerations: Cooking reduces oxalates in spinach and goitrins in kale, improving mineral absorption and reducing thyroid risk.

Green leafy vegetables like spinach and kale have long been celebrated for their remarkable health benefits. As powerhouses of vitamins, minerals, and antioxidants, they are essential components of a balanced diet. However, despite their shared reputation, these two greens have distinct nutritional profiles and properties that make them suitable for different dietary needs and preferences. Choosing one over the other is not about finding a single 'winner,' but rather understanding what each brings to the table and incorporating them both for maximum benefit.

The Nutritional Breakdown

When comparing spinach and kale, it's important to look at the macronutrients and overall composition. Both are low in calories and fat, making them excellent for weight management. They are also high in fiber, which is crucial for digestive health.

Calories and Macronutrients

In a raw, 100-gram serving, both greens are very low in calories, with spinach containing around 23 and kale having about 36 calories, depending on the variety. While spinach provides slightly more protein per 100g, kale is denser in both fiber and carbohydrates.

A Mineral and Vitamin Powerhouse

Both kale and spinach are loaded with vitamins, with each offering a unique set of strengths.

Vitamin A: Spinach boasts significantly more vitamin A, which is essential for vision, immune function, and reproductive health.
Vitamin C: Kale is the clear winner here, offering more than double the amount of vitamin C compared to spinach. This antioxidant is vital for immune support and iron absorption.
Vitamin K: Spinach contains an extremely high amount of vitamin K, which is important for blood clotting and bone health. Kale also provides a substantial amount of vitamin K.
Folate: Spinach is exceptionally rich in folate, a B-vitamin critical for DNA formation and for pregnant women.

Key Differences in Micronutrients

Beyond the vitamins, a closer look at the mineral content highlights the unique contributions of each green.

Iron

While spinach is famed for its iron content, its bioavailability is lower than commonly believed. This is because spinach contains high levels of oxalates, which bind to minerals like iron and prevent the body from absorbing them efficiently. To improve iron absorption from spinach, it should be paired with a source of vitamin C. Kale also contains iron, but in smaller quantities.

Calcium

For calcium content, kale surpasses spinach. One serving of raw kale can provide about 10% of the daily value for calcium, which is triple the amount found in spinach. This makes kale an excellent non-dairy source for bone health.

Antioxidants and Other Compounds

Both vegetables are rich in antioxidants that protect against oxidative stress and chronic diseases. Kale, a cruciferous vegetable, contains cancer-fighting compounds like glucosinolates. Spinach is rich in antioxidants like lutein and zeaxanthin, which are particularly beneficial for eye health. However, kale also contains goitrins, which can interfere with thyroid function, especially if consumed in large raw amounts by those with pre-existing thyroid issues.

Culinary Versatility and Potential Concerns

Both greens can be enjoyed raw or cooked, and the preparation method can influence their nutritional value and taste.

Spinach: Its milder flavor and tender leaves make it a great addition to salads, smoothies, and sauces. It wilts quickly when cooked, making it a fast and easy side dish. Boiling spinach can significantly reduce its oxalate content.
Kale: With a heartier texture and more robust, earthy flavor, kale holds up well to cooking and can be baked into crispy chips, sautéed, or added to soups and stews. Massaging raw kale with oil and salt can help soften its fibers, making it more palatable for salads.

Comparison: Spinach vs. Kale


Feature	Spinach	Kale
Best Known For	High levels of Folate, Vitamin K, and Vitamin A.	Higher in Vitamin C, Calcium, and Fiber.
Key Antioxidants	Lutein, Zeaxanthin.	Quercetin, Kaempferol.
Iron Content	High in non-heme iron, but absorption is limited by oxalates.	Contains some iron, better absorbed than spinach.
Calcium Content	Lower levels, absorption hampered by oxalates.	Excellent non-dairy source, better absorbed.
Potential Downsides	High oxalate content can increase risk of kidney stones.	Contains goitrins, which can affect thyroid function when raw.
Culinary Texture	Tender, mild; wilts easily.	Hearty, chewy; holds up when cooked.

Conclusion

Ultimately, deciding which is healthier, spinach or kale, is a personal choice based on your individual dietary needs and taste preferences. Both are exceptionally healthy and nutrient-dense, and incorporating a variety of greens into your diet is the most effective strategy for ensuring you get a broad spectrum of nutrients. By understanding the unique strengths of each, you can make informed choices to support your overall health. For a comprehensive overview of nutrition facts, the USDA provides an extensive database of information.

Versatile Ways to Enjoy Both Greens

Spinach Applications:
- Toss baby spinach into a vibrant salad with strawberries, walnuts, and a light vinaigrette.
- Blend spinach into a smoothie with bananas, berries, and almond milk for a nutrient boost.
- Sauté it quickly with garlic and a squeeze of lemon juice for a simple side dish.
- Stir it into soups, stews, or pasta sauces just before serving.
Kale Applications:
- Massage raw kale leaves with olive oil and salt to tenderize them for a salad base.
- Bake kale leaves tossed with seasoning for a healthy, crunchy snack.
- Sauté it with garlic and chili flakes for a delicious and simple side.
- Add chopped kale to minestrone or a white-bean soup for extra flavor and texture.

Frequently Asked Questions

Both can be eaten raw or cooked. Raw kale retains more vitamin C, while cooked kale offers more bioavailable calcium and iron. Boiling spinach reduces its oxalate content, improving mineral absorption.

Kale has significantly more calcium per serving than spinach, and it is also more bioavailable since kale does not contain the high oxalate levels found in spinach.

While spinach contains more iron by weight, it also has high levels of oxalates that significantly hinder its absorption. To maximize iron uptake from spinach, consume it with a source of vitamin C.

Spinach is particularly rich in lutein and zeaxanthin, which are great for eye health. Kale, meanwhile, is rich in antioxidants like quercetin and kaempferol.

Consuming large amounts of raw spinach can be a concern for individuals prone to kidney stones due to its high oxalate content. For those with thyroid issues, excessive raw kale intake could be a concern due to goitrins, though cooking mitigates this.

Massaging raw kale with olive oil and a little salt for a few minutes can help break down its tough fibers and make it easier to digest.

Both are excellent choices for weight loss as they are low in calories and high in fiber, which helps with satiety. The best option depends on which you prefer and will eat consistently.

Spinach provides significantly more vitamin K per serving than kale, with a 100g serving of spinach providing over 400% of the daily value.

Spinach, with its milder flavor and tender leaves, is ideal for blending into smoothies, adding to salads, or quickly wilting into pasta sauces. Kale, with its robust texture, is great for baking into chips, braising, or using in hearty soups and stews.