Since we first called kale the new beef in 2011, we thought it might be time to revisit this nutritionally dense vegetable.
Nutritional Benefits of Kale
If kale has been praised as a super-vegetable in recent years, it's no doubt thanks to its rich nutritional breakdown. Kale hails from the cruciferous vegetable family, like broccoli, cauliflower, and Brussels sprouts, and like other crucifers, kale is extremely nutritionally dense. Here are just some of its nutritional perks (all measurements are for 1 cup (67 g) of chopped, raw kale):
- 33.5 calories
- 1.3 g dietary fiber
- 547 mg Vitamin K (684% DV)
- 10302 IU Vitamin A (206% DV)
- 80.4 mg Vitamin C (134% DV)
- 90.5 mg calcium (9% DV)
- .5 mg manganese (26% DV)
- 1.1 mg iron (6% DV)
- 299 mg potassium (9%)
Given this array of nutritional perks, it’s no wonder that kale offers a host of nutritional benefits.
1. Kale Wards off Cancer
Kale has been highlighted by the National Cancer Institute as one of the best anti-carcinogenic vegetables out there. Thanks to sulfur-containing glucosinolates, which are broken down through chewing and digesting into anti-cancer compounds including indoles and nitriles, kale can actually inhibit the development of cancer in the body. These compounds protect cells from DNA damage and help to deactivate carcinogens in the body.
In addition, kale boasts antioxidant properties, which Alyson Greiter, RD, LND, clinical oncology dietician at Cancer Treatment Centers of America at Midwestern Regional Medical Center, says can "protect cells from free radical damage that may lead to cancerous formations in our bodies, thus making it a cancer-fighting food."
2. Kale Boosts Immunity
Dr. Serena Goldstein, a New York naturopath, attributes kale's immunity-boosting properties to its richness in vitamins A, C, and K.
Its immune-enhancing effects are also linked to compounds in the vegetable that keep immunoglobulin A, the antibody responsible for maintaining and enhancing the mucus lining of the gastrointestinal and respiratory tracts, from breaking down. This antibody is crucial for keeping the body’s line of defense against bacteria and viruses strong.
3. Kale Can Boost Metabolism
Kale has been shown by some to boost metabolism thanks to its richness in vitamin C, but watch out -- vegetables like kale and cauliflower have actually been shown to slow metabolism in some cases, especially if eaten raw in large quantities. Try steaming at least some of your kale to counteract this.
4. Kale Promotes Heart Health
Kale contains bile acid sequestrants, which are compounds that can help lower cholesterol levels in the body, thus, in time, leading to better heart health.
According to Greiter, steaming kale only increases these benefits, as it increases the binding ability of these sequestrants, thus lowering cholesterol levels even more significantly.
5. Kale Helps the Body Absorb Iron
As you probably already know, a food containing healthy nutrients is just part of the battle – our body also needs to be able to adequately absorb them. Luckily, kale brings both to the table. Not only is kale a rich vegan source of iron, it also contains vitamin C, which helps with iron absorption. Some studies have shown that just 100 milligrams of ascorbic acid increased iron absorption by 4.14 times; all the more reason to dress your kale salads with a citrus dressing.
6. Kale Strengthens Bones
While most associate bone health with vitamin D and calcium, those aren’t the only important vitamins and minerals to worry about. According to Annemarie Colbin, PhD, author of "Food and Our Bones: The Natural Way to Prevent Osteoporosis," green vegetables are just as – if not more – important. She says that the calcium, vitamin K, and potassium combo found in kale makes it an ideal bone health food.
7. Kale Contributes to Skin Health
Kale is also essential for skin health. Its vitamin C content helps create the collagen needed for skin strength, and its richness in copper boosts the synthesis of melanin, protecting your skin from the sun. Add to that vitamin A, which promotes healthy cell growth and helps prevent against skin diseases, and antioxidants, which prevent the effects of ultraviolet radiation on the skin, and kale is a regular healthy skin cocktail.
8. Kale Aids in Detoxing
Kale is one of your best allies in detoxing, according to naturopathic doctor Dr. Gabrielle Francis. “The chlorophyll in kale makes it a potent chelating agent, which means it binds to toxins and heavy metals and pulls them out of our cells,” she says.
In addition, kale’s high Diindoylymethane (DIM) content means that kale protects us against toxic estrogens coming from pesticides and plastics and clears them out of our systems.
9. Kale Improves Blood Health
Kale can also help improve blood health, according to Goldstein, thanks to its vitamin K and iron content. Vitamin K helps improve the blood’s ability to clot, while iron is important for the health of red blood cells.
10. Kale Helps with Weight Loss
Kale can be an important tool for weight loss due to its low calorie and fat content and richness in fiber. This makeup, which it shares with other crucifers and leafy greens, means that while kale is very nutrient dense, it is also calorie poor and filling. By including kale in your diet, you are more likely to feel full and thus less likely to overeat.
11. Kale Supports Eye Health
Lutein is more commonly associated with carrots, but kale also contains this important carotenoid, along with zeaxanthin. Together, these carotenoids block against ultraviolet light, helping to keep your eyes from being damaged by the sun.
A Word of Warning
Almost as soon as kale became popular, people started warning against the overconsumption of kale, which has been linked to thyroid problems.
“Kale is a goitrogenic, which means that consumed raw it may inhibit thyroid function, an important gland for metabolism,” explains Goldstein. “However, reported cases tend to be many cups at a time. You can mitigate these effects by cooking, steaming, or another type of heat application for even a few minutes.”
In addition, this warning is really only a concern if you have a preexisting condition, as Lori Kenyon Farley and Marra St. Clair, the co-authors of The Juice Cleanse Reset Diet Book and cofounders of Project Juice, explain. “If you have hypo-thyroidism, you do have to be cautions of consuming kale and other cruciferous vegetables,” they say. “If you have normal thyroid function, there is no danger to consuming kale.”
How to Buy Kale
There are more than 50 different types of kale, but some are far more common than others. Feel free to vary the kind of kale you use in your kitchen; Goldstein says that there is no difference in nutritional benefits amongst the different varieties, so you'll just be adding flavor and color to your plate..
- Curly green kale is perhaps the most common variety of kale. It gets its name from the curly shape of its leaves, which are tightly ruffled and need to be washed well. It has a slightly bitter flavor reminiscent of other cabbages.
- Curly kale is also available in red and white versions, both of which are a bit stronger and more peppery in flavor than green kale, which may be why they are not quite as popular.
Lacinato kale image via Shutterstock
- Lacinato kale, also known as dinosaur kale, has more textured, darker leaves and a sweeter, nuttier flavor.
Red kale image via Shutterstock
- Red Russian kale has flat, fringed leaves and, according to Goldstein, is one of the sweetest kales out there.
- Redbor kale is dark red and often ornamental, though it can be edible. It is bright magenta in color.
- Premier kale is a newer variety that stands up quite well to cold.
- Siberian kale's big leaves are some of the hardiest out there. While easy to grow, Siberian kale can be a bit tough.
- Walking stick kale is one unusual variety that can grow up to six feet in height.
Whatever kale you choose, Goldstein says to be sure to pick supple leaves that don’t break easily or show any discoloration. It’s also important to opt for organic kale, especially if you consume a lot of it – while it does not rank on EWG’s dirty dozen, it is in the EWG Dirty Dozen Plus category.
“Leafy greens like kale and collard greens do not meet the traditional Dirty Dozen ranking criteria but were frequently found to be contaminated with insecticides toxic to the human nervous system,” explain Farley and St. Clair.
Kale can be prepared in a myriad of ways, both raw and cooked. Here are just a few of our favorite ways to prepare kale:
Kale salad image via Shutterstock
- This roasted squash is stuffed with farro, feta, and kale for a flavorful vegetarian main.
- Kale salads are a favorite, particularly this one, with millet, dried sour cherries, and pistachios.
- This unique granola is flavored with kale.
- This kale pesto is a great pasta and bruschetta topping.
- Kale chips are one of America's favorite kale snacks.
- Green smoothies are a great way to add kale to your diet -- this one pairs kale with ginger.
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Kale image via Shutterstock