Iron in Kale vs. Spinach. A Nutritional Value Comparison

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Last Updated on June 20, 2022

Kale is a superfood. Spinach is a superfood, but do you know how much Iron is in Kale vs. Spinach? As part of a balanced and nutritious diet, I wanted to make sure I was getting good levels of vitamins and minerals every day. So, I began researching the nutritional value of kale vs spinach, and in my course of research, I got to discover the proportion of iron in kale vs. iron in spinach.

Kale and spinach aren’t even from the same plant family, even though they are often used interchangeably in recipes for things like salads, smoothies, and soups. Thus, contrary to popular belief, neither of them gives super-strength (like spinach did for Popeye), but both have high levels of micronutrients, Vitamin-K and Vitamin C.

Nutritional Comparison of Kale and Spinach

Kale vs spinach nutrinional comparison comparison

From the above chart, even though Kale and spinach both seem to offer similar nutritional benefits, there is some level of differences as well. For example, you will notice that kale has more calcium and more than three times the amount of Vitamin C as spinach has. While spinach has more folate, Vitamin K, Vitamin A and Magnesium. Nevertheless, these differences don’t make one better than the other overall. As a matter of fact, just as eating a variety of other types of foods convey a good nutritional diet, kale and spinach are both very healthy and highly nutritious vegetables.

And when you look further, you’ll find out that both kale and spinach are both high in antioxidants, natural chemicals that help prevent oxidative damage to your cells and therefore, help in protecting your body from chronic diseases.

Check the Full Report of Kale Nutrients

Check the Full Report of Spinach Nutrients

Iron Comparison

In regards to iron components, spinach wins the iron battle against kale by a long-shot. One cup of spinach contains up to 15 to 30% of your daily iron requirements (Recommended Intakes according to a person’s age and sex). On the other hand, kale only has a smaller percentage of iron.


Raw Spinach is better than Cooked Spinach?

A lot of people are still of the erroneous belief that raw spinach contains a higher level of iron. But the truth is, raw spinach contains oxalic acid or oxalate, a compound that binds to calcium and iron, making them harder for the intestines to absorb. When you cook or boil your spinach, the oxalate activity decreases making the iron easier to absorb to your body.

Raw Spinach is better than Cooked Spinach?

Nutritional Benefits of Kale

In addition to the vitamin benefits you get from kale, it’s loaded with antioxidants, like quercetin and kaempferol, that have anti-inflammatory and anti-viral effects.

Kale can has a potential cholesterol-lowering effect as well. Over time, lowering your cholesterol can lead to a reduced risk of heart disease. In one study, drinking kale juice once a day for 12 weeks showed an increase in the “good” cholesterol (HDL) and lowered the “bad” cholesterol (LDL). Steamed kale is actually 43% as potent as cholestyramine. And cholestyramine is a cholesterol-lowering drug that works in much the same way as kale.


Nutritional Benefits of Spinach

Spinach, like kale, has many health benefits besides boosting your vitamin intake.

High in insoluble fiber, and low in carbs, spinach can help bulk up stool and may help prevent constipation. Spinach is also high in Lutein and Zeaxanthin, both of which improve eye health in particular.


Side Effects, Interactions, Dosage, and Warning


Spinach is high in oxalate. Oxalate is a compound that binds to calcium and iron in the intestines and prevents the absorption of it. An oxalate-rich diet increases the amount of oxalate in your urine, which can lead to the formation of calcium oxalate kidney stones. While there are several types of kidney stones, it is believed that the vast majority of kidney stones are calcium oxalate kidney stones.

Iron in Kale vs.Spinach. A Nutritional Value Comparison

A diet rich in calcium helps reduce the amount of oxalate being absorbed by your body, so stones are less likely to form.
People who are at a high risk of kidney stones are encouraged to limit their intake of foods high in oxalate and increase the intake of calcium in their diet (for more details consult a specialist).

Still, according to a study, boiling vegetables before eating them reduces soluble oxalate content by 30-87% and is more effective than steaming.


Kale might have goitrin in it, a compound that can potentially interfere with thyroid function by decreasing the uptake of iodine. This is true of all cruciferous vegetables like cauliflower, broccoli, brussels sprouts, and cabbage.

Iron in Kale vs.Spinach. A Nutritional Value Comparison

Also, recent studies have indicated that eating foods high in goitrin in moderation, is fine and won’t be likely to harm most people. Those that do need to be careful are women with a very low intake level of iodine.

Also, like the oxalates in spinach, cooking cruciferous vegetables will kill the enzyme responsible for the release of goitrin. If you have thyroid problems, cooking your kale before eating it, and making sure you eat enough foods high in iodine (foods like seafood and dairy), will help prevent any potential problems from the ingestion of goitrin.

So which is better: Spinach or Kale?

Both of these delicious vegetables are very good for you. Spinach is better if you are looking for a higher level of iron and fiber in your diet. Kale on the other hand, is a better option when looking for a food that has the added benefit of lowering cholesterol, while also providing a fairly significant dose of Vitamin K.

Given that Kale has a lower amount of oxalate, the calcium and iron it provides, are more easily absorbed by the human digestive system.

The choice isn’t really about which one is better for everyone, but which is better for you. Frankly speaking, eating a variety of highly beneficial vegetables is the ideal solution.

Green Iron Boosting Smoothie Recipe

Here an Amazing Smoothie Recipe full of Iron:


  • Spinach is very high in iron and fiber and has nutritional elements to boost your eye’s health.
  • Kale is one of the best superfoods because it has a wide variety of compounds that can help with everything from eye health to lowering cholesterol and is low in oxalate.
  • They are interchangeable in many recipes and are both delicious and healthy.


Are there recipes you especially like to use with either of these green vegetables? Perhaps you’ve even found ways to get your kids to eat and like them? Let us know in the comment section below!

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