Kale Vs. Spinach: Health Benefits, Nutritional Facts, & Risks

Spinach and kale are the forerunners when it comes to the battle of the greens. Both are known to be highly nutritious and beneficial to your overall health when included in your diet. But is one better than the other? Do both have similar nutrients? Can you eat them raw? Let’s find out how kale vs. spinach fare against each other when it comes to taste, nutrition, health benefits, and any potential side effects.

About Kale And Spinach

Kale belongs to the Brassica oleracea plant family and is at times referred to as leaf cabbage. Kale is a closer cousin of the wild cabbage. Kale leaves are edible and have a slightly bitter, peppery aftertaste. However, a few varieties of kale are not edible and are strictly ornamental.

Spinach belongs to the Caryophyllales order of leafy flowering plants native to western and central Asia. It is part of the amaranth family of plants and is closely related to quinoa and beetroots. Spinach has a mild flavor and can be eaten raw or cooked.

Did you know?

Kale was cultivated for consumption even during 2000 BCE in the eastern Mediterranean and Anatolia. Spinach, on the other hand, is believed to have originated in ancient Persia 2,000 years ago.

While both are nutrient-dense leafy vegetables that can make for a well-balanced, wholesome meal, there are a few differences in their nutritional composition and health benefits thereof. Let’s see how they compare against each other in the sections below.

Nutrition Facts: Kale Vs. Spinach

Both spinach and kale are highly nutritious, low-calorie leafy greens that can enrich your diet with many important vitamins and minerals.

According to the USDA, here’s how a 100g serving of kale and spinach compare to one another (1), (2):

While both kale and spinach offer similar nutrients, there are a few key differences as well. For instance, kale contains more than twice the amount of calcium, fiber, and vitamin C, while spinach provides more vitamin K, vitamin A, magnesium, iron, and folate.

Both contain varying amounts of several important micronutrients including vitamin A and riboflavin.

Even with their varied nutrient concentrations, they both make for a healthy addition to your diet. Including either of them in your daily meals can benefit you in several important ways.

Comparing Kale And Spinach: What Are The Health Benefits?

Kale and spinach with their similar nutrient profiles, provide us with comparable health benefits as well. Let’s see how.

• Rich In Healthy Dietary Fiber

Kale has twice the amount of dietary fiber than spinach (1), (2). Fiber helps improve your digestion and regularize bowel movements. Additionally, it also helps lower the risks of obesity, diabetes, cardiovascular, and gastrointestinal diseases (3), (4). It is important to add dietary fiber to your meals, given that most people fall short of the daily recommended allowance of fiber (5).

• Rich In Immunity-boosting Antioxidants

Spinach and kale are both important sources of antioxidants like beta-carotene, lutein, and the vitamins A, C, and K. Antioxidants help get rid of toxic free radicals in your body, prevent oxidative damage, and protect you against chronic diseases like diabetes, cancer, and cardiovascular diseases (6), (7), (8).

• May Help Improve Heart Health

Including kale and spinach in your diet has also been shown to improve heart health by reducing various risk factors like high blood pressure and high levels of cholesterol. A 12-week study in men with high cholesterol reported that drinking kale juice along with your meals might help improve your cholesterol levels (9).

Similarly, spinach with its dietary nitrates was found to be effective in improving both systolic and diastolic blood pressure, showcasing key spinach benefits (10).

Quercetin and kaempferol, two important flavonoids found in both kale and spinach have been shown to help lower high blood pressure levels and improve your overall cardiovascular health overall (11).

• Might Help Fight Cancer

Both the leafy green vegetables contain certain bioactive compounds that have shown promising cancer-fighting properties (1313), (14). These compounds have also helped enhance the effectiveness of different cancer treatments by inhibiting the growth and spread of cancer cells (15).

• Might Aid Weight Loss

Kale and spinach both have a high content of water. They provide you with about 90g of water per 100g serving (1), (2). They are also high in important nutrients and low in fats and calories. Adding these low-calorie, energy-dense leafy greens to your diet might prove beneficial in your weight loss plans (16), (17).

• May Help Prevent Birth Defects

Spinach contains more than twice the amount of folate as in kale and can be a healthy addition to your diet during pregnancy (1), (2). Folic acid, derived from folate, may be effective in preventing neurological defects like spina bifida in developing fetuses. Women of reproductive age and planning to conceive are recommended a daily intake of 0.4‐1.0 mg of folic acid as dietary supplements (18).

• May Be Good For Your Bones

Kale and spinach are both high in calcium and vitamin K. While kale has more than twice the amount of calcium in spinach, the latter has more vitamin K (1), (2). Calcium and vitamin K are vital nutrients that help improve and maintain your bone health reducing the risks of osteoporosis (19).

Hannah Cutting Jones, a blogger, acknowledges the challenges faced by kale lovers but offers practical suggestions to address the concerns, such as thorough washing, freezing, and alternative cooking methods. Additionally, she believes the amazing kale benefits are worth the trouble, “I am going to keep eating kale, in spite of this bump in our otherwise fabulous friendship (i)!”

While the above benefits might encourage you to include kale and spinach regularly in your diet, you should also be aware of their potential side effects and risk factors.

Kale Vs. Spinach Risks

There are a few things you should keep in mind before including kale and spinach in your diet.

• Kidney Stones

Spinach contains large amounts of dietary oxalate, a compound that binds to and prevents calcium absorption in your body (20). A higher intake of oxalate-rich foods might lead to the formation of calcium oxalate kidney stones (21), (22). Hence, people with a higher risk of kidney stones should limit their intake of spinach and other oxalate-rich foods (23). Boiling spinach might be effective in reducing the dietary oxalate concentration by up to 87% (24).

• Bacterial Contamination

Leafy greens, especially when eaten raw, might lead to food poisoning and bacterial contamination. In a major E.coli outbreak in 2006, 80% of the cases were traced to spinach contamination (25). Another analysis in 2013, reported 6.6% of the samples of farmed spinach tested positive for the bacteria (26). Similar contamination with E.coli and salmonella can also be found in kale due to poor cultivation and handling practices (27).

Quick tip

Soak kale and spinach in a solution of one part vinegar and four parts water for 5-10 minutes to reduce the risk of contamination. Also, keep them away from potential sources of contamination such as raw meat.

• Thyroid Imbalance

Kale and other cruciferous vegetables like broccoli and brussels sprouts are known to contain goitrin. It is a compound that may potentially lower the iodine levels, leading to an imbalance in the production of thyroid hormones (28). While spinach may also contain goitrin, it is usually less in comparison to kale. Also, it is better to consume them cooked as that seems to help reduce the potential risks (29).

Well, even with the above side effects, the health benefits of kale and spinach outweigh their potential risks and make them a healthy addition to your diet. Going further let’s see how you can include these nutrient-dense leafy greens in your diet.

How To Prepare Kale And Spinach?

When it comes to flavor and texture, spinach is more tender, delicate, and mild, in comparison to kale. This makes it easier to incorporate spinach in a variety of dishes. It can be eaten blanched and pureed, added to soups, and gravies. You can also use raw spinach to make healthy green smoothies, salads, and sides. Its mild flavor combines well with rice, pasta, eggs, and beans as well.

On the other hand, kale is slightly tough and bitter with a peppery taste. You should look for fresh and firm dark green leaves. Try to avoid purchasing brown or wilted leaves and remember to remove its tough middle portion to avoid the bitter taste. While spinach tends to wilt faster on cooking, kale can withstand longer cooking times and thus work better for stew, saute, or baked kale chips. If you find the flavor of kale too pungent, you can mix it along with other greens or opt for baby kale that is milder in taste.

Frequently Asked Questions

Can I replace spinach with kale?

Yes. You can use kale for spinach in many recipes. But choose the right type of kale depending on the recipes you prepare. Kale works great as a substitute for spinach in soups, casseroles, or salad.

Is kale or spinach better in a smoothie?

Spinach is the best option to add to a smoothie because of its mild taste and the presence of antioxidants, vitamin A, and minerals like potassium, magnesium, and iron.

Is kale good for hair growth?

Kale is good for hair growth and is said to strengthen hair strands. However, there is no direct evidence linked to it. Hair growth is influenced by various factors like genetics, hormones, and overall nutritional intake (30) (31) (32). Since kale is packed with nutrients, including it in your diet may contribute to overall well-being, potentially benefiting your hair indirectly. But it is not a guaranteed solution for hair growth.

Is spinach bad for acid reflux?

There is no direct evidence that suggests that spinach may be bad for acid reflux. In fact, research suggests that it may have an acid-neutralizing effect on the body (33). However, individual reactions vary and you may experience acid reflux with spinach. Anecdotal evidence suggests that eating too much spinach may cause some discomfort and, in some cases, acid reflux as well.

Both spinach and kale are powerhouses of nutrition and offer impressive health benefits. Check the video below to find out how you can incorporate spinach and kale into your diet to fetch optimum benefits!