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It has green or purple leaves, it rivals oranges in the vitamin C department, and it was named one of the “Top 10 Food Trends of 2012” by Time Magazine…
It’s kale!
Kale’s popularity has soared in recent years, and it’s not hard to see why. Kale is a real superfood! As you’ll soon discover, kale is chock full of nutrients like vitamins C and K1 and calcium (there’s actually a surprising amount of calcium in kale– it even ranks on our list of “Top Calcium-Rich Foods“).
Now, kale is a cruciferous vegetable, in the genus Brassica of the Brassicaceae family of flowering plants. That makes kale a close relative of other green vegetables like broccoli, bok choy, Brussels sprouts and cabbage… but kale is probably the most popular of the whole bunch!
Keep reading to discover how much calcium kale provides (as well as other nutrients), the amazing health benefits of kale and some recipe ideas to fall in love with.
How Much Calcium is in Kale?
Kale is much more than a colorful alternative to lettuce. It’s a superfood!
As we mentioned earlier, there’s a surprising amount of calcium in kale. In fact, 100 g of kale provides 254 mg of calcium.
But that’s not the most surprising nutritional fact about kale… pound for pound, it provides almost double the amount of vitamin C that navel oranges do! It’s true, 100 g of kale has 93 mg of vitamin C, while 100 g of navel orange provides 59 mg. For reference, the Recommended Dietary Allowance for vitamin C is 75 mg for adult females and 90 mg for adult males (smokers require an extra 35 mg of vitamin C a day.)
What’s more, kale contains a high amount of vitamin K1. As you’ll discover in the “Health Benefits of Kale” section, this could pay dividends for your bone health!
Finally, kale contains incredible amounts of two different kinds of antioxidants; carotenoids and flavonoids. Lutein and beta-carotene (the precursor to vitamin A) are the stand-out carotenoids in kale. As for flavonoids, there are over 45 in kale, but the most celebrated are quercetin and kaempferol. We’ll delve into the benefits of these antioxidants in the health benefits section a little further down.
Fun fact:
Flavonoids and carotenoids are responsible for giving fruits and vegetables their bright colors!
| Nutrients in Kale | Amount per 100 g |
| Energy | 35 kcal |
| Total Carbohydrate | 4.42 g |
| Dietary Fiber | 4.1 g |
| Sugars | 0.99 g |
| Total Fat | 1.49 g |
| Calcium | 254 mg |
| Potassium | 348 mg |
| Vitamin C | 93.4 mg |
| Vitamin K (phylloquinone) | 389.6 µg |
4 Health Benefits of Kale
An Antioxidant Boost
Kale contains credible amounts of several carotenoids and flavonoids which are both classes of antioxidants. That’s great news for your overall health, as antioxidants can reduce and prevent the damage free radicals cause to your cells. Free radicals are the by-product of everyday metabolism and can be a factor in diseases like cancer, arthritis, Alzheimer’s, and heart disease.
In fact, studies have found a positive association between the consumption of foods containing the flavonoid kaempferol, in particular, and a reduced risk of developing several disorders such as cancer and cardiovascular diseases.
What’s more, flavonoids have been shown to have potential anti-viral and anti-inflammatory properties too. The anti-inflammatory properties are a major bonus for your bone health, as chronic, low-grade inflammation caused by a poor diet and environmental toxins (amongst other factors) can contribute to osteoporosis!
Helps Keep Your Blood Pressure in Check
Chalk up another benefit for the flavonoids! This time it’s quercetin delivering the goods.
Quercetin is another of a large number of flavonoids found in kale. (You’ll also find quercetin in onions, berries, and red wine). Quercetin makes the list of kale health benefits because research shows it can help lower blood pressure, especially in individuals with hypertension (high blood pressure.)
A double-blind, placebo-controlled, crossover trial showed that supplementing with 730 mg of quercetin a day for 28 days consistently reduced the blood pressure of participants with hypertension compared to a placebo.
Now, researchers know that it is quercetin that helps lower blood pressure, but they’re still not quite sure why. Currently, the anti-oxidative properties of quercetin are thought to make it so effective at lowering blood pressure, but there’s still no solid evidence to support this theory.
A Bone Health Bonus
As we mentioned in the nutrition section, kale provides a high amount of vitamin K1… in fact, kale is the best-known food source of vitamin K1 on the planet!
Now, vitamin K1 is primarily used for blood clotting. If you didn’t have any vitamin K1 in your body, you’d bleed to death from the tiniest cut! But if you have a high enough level, your body will convert the extra vitamin K1 to vitamin K2– which is crucial for your bone health. Although getting vitamin K2 directly is best.
Vitamin K2 is responsible for activating the proteins that direct calcium around your body:
- Osteocalcin: Directs the calcium you consume to where you need it… your bones and teeth!
- Matrix Gla protein: Keeps calcium out of the places you don’t want it– your blood vessels, organs and soft tissues.
Think of these proteins as your body’s traffic signs designed specifically for calcium.
You can read more about vitamin K1 and vitamin K2 on our dedicated page by clicking here.
Helps Protect Your Vision
It’s the turn of the carotenoids in kale to deliver a health benefit.
Lutein, in particular, has been linked with protecting vision and preventing age-related maculopathy. The macula is the central area of your retina. It gives you the ability to see in 20/20 and provides the best color vision. So when this area of your eye degenerates with age, it’s known as age-related maculopathy.
Lutein and another carotenoid called zeaxanthin are present in your macula, so they’re referred to as macular pigment. And research suggests the level of lutein in the macula is associated with the risk of age-related maculopathy.
No matter your age, we’ve got some kale recipes in the next section that make getting enough lutein, and all the other beneficial nutrients in kale, into your diet easy. If you’ve got children who are fussy eaters we’ve got some clever recipes to hide kale. Or if you just want a simple, tasty way to add kale to your diet, we’ve got you covered too.
Interactions and Precautions of Kale
Kidney Stones From Oxalic Acid?
A common debate surrounding leafy greens like kale and spinach is the oxalic acid content. Some people avoid kale and other foods out of fear that the oxalic acids will cause kidney stones and inhibit calcium absorption.
Truth is, the missed nutritional opportunity by avoiding these foods outweighs the minimal risks. Plus, research shows that as long as you’re consuming the recommended daily amount of calcium, absorption won’t be an issue. If you’d like a little more information on the oxalic acid debate, check out our “Does Oxalic Acid in Spinach Inhibit Calcium Absorption?” page.
Thyroid Issues
There’s also a slight concern that cruciferous vegetables like kale could be related to thyroid issues like hypothyroidism. See, cruciferous vegetables contain goitrogens that affect the way your thyroid gland uses iodine.
But here’s the thing; you’d have to be eating an enormous quantity of kale, or any cruciferous vegetable, for it to cause a thyroid issue.
If you already have a thyroid issue, it’s best to consume your cruciferous vegetables cooked and to stick to a maximum of one or two servings a day.
Go Organic Whenever Possible
Every year, the Environmental Working Group (EWG) provides a list of produce grown with the most pesticides. The worrying news for kale fans is that kale made the list in 2018.
Consuming produce that contains a lot of pesticides is bad for your health for several reasons, including that pesticides promote inflammation and bone loss!
We advise that you purchase organic kale, and any other produce, whenever possible. Plus, you can check out a summarized version of the (EWG’s) list of dirty and clean produce by clicking here.
Other Calcium-Rich Foods
Kale is much more than an up and coming food trend. It’s a fully fledged nutrition powerhouse providing significant amounts of calcium, vitamin C and vitamin K! If that weren’t enough to convince you to add kale to your diet, it’s a truly versatile ingredient that can add a hint of color and flavor to a whole host of recipes.
If you’d like to see more calcium-rich foods, click here to find some of the best on the planet.
Or if you want to discover more about one particular food, here are some of the most popular calcium-rich foods explained: