You see kale everywhere these days. It seems like everyone is drinking kale smoothies, eating kale chips and incorporating kale into salads.
If you have any interest in your health, you might already know that kale is great for you. However, you may not know exactly why.
Find out more about this nutrient-packed superfood so that you can understand the hype.
Kale 101
Kale is a leafy vegetable that is related to the cruciferous vegetable family.
Many people think of green as a green, curly leaf, but the leaves may be purple, bluish or smooth. Curly kale may be the most commonly found type in the grocery store.
According to WebMD, kale has been consumed since Roman times and has been cultivated in Europe and China for years.
It's a versatile vegetable with a relatively neutral flavor that can be prepared in many different ways.
Even if you're not a huge fan of greens, you can almost certainly find a way to enjoy kale.
Let's take a look at all the benefits of this delicious vegetable for your health!
20 Health Benefits of Kale
The following are the 20 evidence-based health benefits of kale:
1. Kale is Packed With Nutrients
One cup (67 g) of raw kale has the following nutrients in abundance ( 1):
Vitamin A (10,302 IU or 206% RDA)
Vitamin A is a retinoid that is essential for optimal function of the immune system, the nervous system, the reproductive system and vision ( 2).
While it is possible to achieve toxicity from animal-based vitamin A, the body only converts plant-based beta carotene into vitamin A as needed.
Therefore, eating kale may be a safer way to get your vitamin A than through a supplement or animal-based food products ( 3, 4, 5).
Kale contains 206% of the recommended daily allowance of vitamin A.
Vitamin K (547 mcg or 684% RDA)
Vitamin K is crucial for helping the blood to clot properly and supporting bone health ( 6).
It has been shown to reduce the risk of osteoporosis and coronary heart disease ( 7, 8).
Because vitamin K is much less bioavailable from food than from supplements, the fact that there is so much of it in just one cup of kale helps ensure that you are absorbing enough if you eat this vegetable ( 9).
Vitamin C (80.4 mg or 134% RDA)
The human body doesn't naturally make vitamin C on its own, so the vitamin must be acquired from food or supplements ( 10).
Although many people think of Vitamin C as the nutrient that helps prevent you from getting sick.
Vitamin C also helps the body make and use collagen, certain neurotransmitters and protein ( 11, 12).
Vitamin B6 (0.2 mg or 9% RDA)
Vitamin B6 is necessary for the body to metabolize proteins, carbohydrates and fats ( 13).
Researchers believe that vitamin B6 may help reduce the risk of cardiovascular disease ( 14).
The vitamin has also been linked with a reduced risk of certain cancers, age-related cognitive decline and even morning sickness during pregnancy ( 15, 16, 17).
High consumption of vitamin B6 from food has not been shown to be detrimental to your health ( 18).
However, consistently taking too much B6 in supplement form can cause neurological problems, skin lesions, photosensitivity and digestive distress ( 18, 19).
Calcium (90.5 mg or 9% RDA)
Although you may associate calcium with dairy products, green leafy vegetables, like kale, are a great source of the nutrient.
Calcium is the most plentiful mineral in the human body ( 20).
The majority of the calcium in your body is used to support the structure and function of your bones and teeth.
It is also necessary for hormone secretion, cellular communication, muscle function, contraction and dilation of the blood vessels and nerve transmission ( 21).
Magnesium (22.8 mg or 6% RDA)
Magnesium is abundant in the human body and helps control biochemical reactions related to protein synthesis, muscle and nerve function, blood pressure management and blood sugar regulation ( 22).
Magnesium can reduce the risk of heart attack and stroke ( 23, 24). People who eat magnesium-rich diets have a lower risk of diabetes ( 25, 26).
Studies show that women can increase their bone density by consuming magnesium, possibly reducing the risk of osteoporosis ( 27).
People who experience chronic headaches or migraines may be deficient in magnesium ( 28).
Kale also contains 10% of the RDA of copper, 9% of the RDA of potassium and 3% or more of the RDA of iron, phosphorous and some other B vitamins. That's just in one cup.
One cup also contains just 33 calories and 6 grams of carbohydrates.
If you saute kale, add it to a smoothie or make chips with it, you can easily consume much more than one cup, packing your system with vital nutrients in just one meal or snack.
2. Kale Has Potent Antioxidants
Kale contains high levels of antioxidants, including the following ( 29):
What are antioxidants?
They're compounds that fight oxidative stress in the body ( 30).
Oxidation is normal within the body.
The body needs oxygen to survive, and when the body is at homeostasis, there is a balance of oxidation and antioxidants.
However, certain cells react to oxygen by creating free radicals. Changes in homeostasis can increase the number of free radicals produced in the body.
Free radicals are not bound to any other molecule. Therefore, they seek other molecules with which they can combine.
When a free radical attaches to another molecule, like a protein cell or DNA, it causes damage. That damage produces more free radicals, and a chain reaction begins.
Biological researchers have been intensely studying oxidative damage in recent years because it is thought to be one of the main causes of many health problems, like diabetes and cancer ( 30, 31).
Two of the flavonoids that are abundant in kale, quercetin and kaempferol, have been found to have many health benefits, including ( 32, 33, 34, 35):
- Protecting the cardiovascular system
- Lowering blood pressure
- Reducing inflammation
- Fighting viruses
- Improving mood
- Lowering the risk of cancer
Just be aware that cooking kale can lower its antioxidant activity, especially the benefits of vitamin C and polyphenols ( 29).
To get the most antioxidant benefit from kale, it is recommended to eat it raw or blanch it quickly in boiling water.
3. Eating Kale Can Help You Manage Your Cholesterol
Cholesterol has been made out to be the enemy, but it is important for several bodily functions.
Cholesterol helps synthesize certain acids that aid in the digestion of dietary fats.
When you eat something with fat in it, your liver uses up some of the cholesterol in the blood to make bile acids.
Those bile acids help the fat be absorbed through the gut.
Then, the bile acids return to the bloodstream. Bile acid sequestrants are compounds that prevent the bile acids from being reabsorbed after they are used for digestion.
Because the digestive system then has less bile available, the liver must synthesize more from cholesterol.
This process lowers levels of cholesterol that circulate through the blood.
Kale contains bile acid sequestrants and is one of the most effective vegetables for binding bile acids.
Kale was found to bind about 25% of the bile acids that Cholestyramine, a bile-acid-sequestering medication did ( 36).
This is promising for the use of kale in general management of cholesterol.
One study showed that people who drank kale juice for 12 weeks saw a 27% increase in HDL, the "good" cholesterol. The participants LDL levels also decreased by 10% ( 37).
Although we mentioned that cooking kale can reduce its antioxidant effects, steaming the vegetable can improve its ability to bind bile acids.
In one study, researchers found that steaming kale makes it 43% as effective as Cholestyramine in lowering cholesterol ( 38).
4. Kale Can Keep You From Getting Sick
An apple a day may keep the doctor away, but a handful of kale could work just as well, if not better.
One cup of raw kale contains about 80 mg of vitamin C.
This is 8 times the amount of vitamin C found in a cup of raw spinach ( 39).
One cup of orange segments contains only slightly more vitamin C than kale, about 95 mg ( 40).
That apple that supposedly keeps you healthy only contains about 6 mg of vitamin C ( 41).
While you may associate vitamin C with helping ward off the common cold, studies show that it is only marginal beneficial when it comes to preventing viruses ( 42, 43).
However, because vitamin C is such a potent antioxidant, it can help lower the risk of other diseases, including ( 44):
Vitamin C also helps the body produce collagen, a structural protein that helps maintain healthy skin. As you age, you lose collagen, causing wrinkles and sagging skin.
5. Kale Can Lower Your Risk of Cancer
Cancer is characterized by the overgrowth of certain cells. Many of the substances in kale are linked with a lowered risk of cancer.
We have discussed the benefits of the antioxidants in kale that help to restore DNA damage that can lead to cancer.
Many studies have investigated the role of Brassica vegetables, like kale, in protecting against cancer ( 45).
One of the substances in kale-family vegetables is sulforaphane, a protective enzyme that has been found to have anticarcinogenic effects ( 46, 47).
Sulforaphane can also help protect healthy cells from the toxic effects of anti-cancer drugs ( 48, 49, 50).
The indole-3-carbinol in kale has also been shown to have anti-cancer effects ( 45, 51).
Research has found that people who eat cruciferous vegetables, such as kale and broccoli, may have a lower risk of cancer. However, the evidence is inconsistent ( 52, 53).
6. Kale Contains High Levels of Vitamin K
One cup (67 g) of kale contains over 6 times the RDA for Vitamin K (547 mcg or 684%).
Vitamin K is essential for helping the blood to clot.
In fact, it is recommended that newborns receive a vitamin K injection at birth to help get the blood clotting process started.
There are different types of vitamin K. The type of vitamin K provided by kale is vitamin K1 ( 54).
This is the type that has been associated with diminished bone loss in older women ( 55).
People who take blood thinners may need to check with a doctor before consuming too much kale.
Vitamin K can increase the risk of blood clots in people who are at risk for developing them ( 56).
However, consuming vitamin K via healthy vegetables should not overload the system the way taking it in supplement form could.
7. Kale May Lower Your Risk of Diabetes and Heart Disease
Kale contains many minerals that some people are deficient in.
The magnesium in kale has been shown to protect against type 2 diabetes and heart disease ( 57).
The potassium in kale has also been associated with a reduced risk of heart disease as well as a reduction in hypertension ( 58).
Some researchers have hypothesized that calcium, which is plentiful in kale, may help reduce the risk of heart disease by lowering cholesterol and the ability of the body to absorb fat ( 21).
However, studies have found inconsistent evidence linking calcium to improved heart health.
Researchers have raised concerns that taking too much calcium in supplement form could actually increase the risk of cardiovascular disease ( 59, 60, 61).
For this reason, consuming calcium through foods may be safer than taking it as a supplement.
Oxalate may prevent minerals from being absorbed ( 62). Kale is low in oxalate compared to other leafy greens.
8. Kale Contains A Safe Type of Vitamin A
The body makes vitamin A in several ways. Some types of vitamin A are derived from animal-based food products, like liver.
The plant-based form of vitamin A actually exists as beta-carotene in the fruit or vegetable.
When you eat this antioxidant, the body transforms it into vitamin A within your system ( 63).
The body is better at absorbing vitamin A from animal products than synthesizing it from beta-carotene ( 64).
However, it's possible to overdose on vitamin A supplements, whereas beta-carotene is much less toxic ( 65).
Studies have found that the levels of vitamin A in the body do go up after you eat kale ( 66).
9. Kale May Aid in Weight Loss
When you're trying to lose weight, it helps to understand which foods can fuel you without adding large amounts of calories.
The fiber and water content in kale can make you feel full even though it only has 33 calories per cup.
Kale also contains 2 gram of protein per cup.
If you saute the kale down, you could easily consume 4 to 5 cups at once.
This could deliver 10 grams of protein and 35 grams of complex fibrous carbohydrates, which help you feel full.
Romaine lettuce, which is often consumed during weight-loss efforts, only contains 1 gram of protein and 2 grams of complex fibrous carbohydrates in one cup ( 67).
While it's low in calories, it's not likely to help you feel as satisfied as kale.
Kale is considered to be a food with low energy density. Studies show that low-energy-density foods can help you lose weight ( 68, 69).
10. Kale is Good For Your Eyes
The antioxidants and beta-carotene in kale are good for eye health. Lutein and zeaxanthin are vitamin A-based antioxidants that are abundant in kale.
Research shows that these antioxidants are liked with a decreased risk of cataracts and macular degeneration, two eye problems that may occur as you age ( 70, 71).
11. Kale can help detoxify your body.
As we go about our everyday lives, we are exposed to toxins in our environments as well as the products we use and consume.
We can benefit from routinely cleansing our bodies of these toxins to restore balance and health.
One way you can do this is simply by eating more kale.
Kale contains special compounds made from glucosinolates called "isothiocyanates," or "ITCs."
These compounds have powerful detoxification properties ( 72).
You already know that kale contains antioxidants that can combat radicals in the body. Now you know a second way in which kale helps to protect your body.
First, the antioxidants destroy the dangerous toxins. Then the ITCs help to flush them out of your body.
Additionally, ITCs help to slow the growth of tumor cells and stimulate their destruction ( 73).
This contributes to kale's cancer-fighting properties.
12. Kale has powerful anti-inflammatory properties.
While inflammation does play an important role in bodily health, when the fires burn out of control, they can cause pain, discomfort, and chronic health issues
Chronic inflammation is a condition which is associated with many diseases in the body, a few examples being arthritis, IBD, and ulcerative colitis.
Inflammation can also be an acute problem associated with injury or illness.
One way to combat the damage caused by excessive inflammation and to help mitigate the symptoms and progression of inflammatory diseases is to eat an anti-inflammatory diet.
Kale has powerful anti-inflammatory properties and can be a key component in such a diet.
Part of the reason for this is that kale has an ideal ratio of omega-3 and omega-6 fatty acids ( 74).
Omega-6 fatty acids worsen inflammation while omega-3 fatty acids curb inflammation.
As the research above reports, western diets are out of balance.
Most of us are eating too many foods which are rich in omega-6 fatty acids and are not getting enough omega-3 fatty acids in our diets.
By eating more kale and fewer processed foods which contain high amounts of omega-6, you are helping to balance out your fatty acid intake.
The result is a diet which is less inflammatory.
If you can make your ratio ideal across the board by eating other healthy foods like kale, you might even achieve an anti-inflammatory diet.
This diet will help to stave off the fires of inflammation now and over the years to come. This in turn will help to ensure your health now and in the future.
13. Kale is rich in folate.
When you hear the word "folate," you may immediately think about pregnancy.
This is because doctors advise pregnant women to increase their folate intake so as to prevent birth defects and promote proper brain development in infants ( 75).
The safety and toxicity of synthetic folic acid supplements are however still under review ( 76).
Folic acid supplementation has been potentially linked to a number of health risks and conditions including epilepsy, concentration issues, insomnia, mood swings, vitamin B12 deficiency, and zinc absorption issues.
This does not necessarily mean that folic acid supplementation is the wrong option for everyone, but it does mean that turning to natural sources where possible is wise.
Kale contains high concentration of folate. 1 cup of chopped kale gives you 5% of your daily recommended value.
So if you are pregnant or need to increase your folate intake for other health reasons, adding more kale to your diet is a safe, effective and delicious way to do it.
14. Eating kale regularly can help protect your brain health.
With diseases like Alzheimer's and other forms of dementia on the increase with no known cure, it is more important than ever to take steps to protect brain health.
When it comes to doing that, kale is one of the best things you can eat.
It contains 45 or more flavonoids, which can reduce your risk of getting a stroke. You also now know that kale has a high omega-3 fatty acid content.
Not only are omega-3 fatty acids powerful anti-inflammatory compounds, but they also are vital for brain health, improving and protecting memory, function, and performance ( 77).
Kale's antioxidants also have anti-inflammatory effects, and may boost cognitive function following traumatic brain injury ( 78).
15. Consuming kale is good for fortifying your bones.
Kale is rich in calcium. One cup of chopped kale contains 90.5 mg of calcium, accounting for 9% of your daily required value.
Bones which are deficient in calcium have a low bone mass, which means that they are prone to fractures ( 79) as well as health problems like osteoporosis.
You also now know that kale contains a very high amount of vitamin K.
Insufficient vitamin K intake also has been linked to an increased risk of fractures ( 80, 89).
Vitamin K also can help to boost your body's absorption of calcium while reducing urinary excretion of the same.
Indeed, according to the source just linked, you can get about the same amount of absorbable calcium from a cup of cooked kale as you can from a cup of cow's milk.
So kale helps to protect bone health through the combined action of vitamin K and calcium.
16. Kale can protect your DNA.
As you now know, kale contains high levels of vitamin C. Vitamin C can help to prevent IMA-induced DNA damage ( 81).
This may have to do with increased concentrations of hepatic lutein ( 82).
Researchers still do not fully understand the mechanism through which kale provides DNA protection, but the relationship does appear to be established.
17. Improve the appearance and health of your hair and skin.
If you have been looking for a nutritious food that can nourish your hair and skin, kale is a great choice.
Kale contains a carotenoid called beta-carotene. Your body converts this carotenoid into vitamin A.
Vitamin A (retinol) can help to reduce the appearance of fine wrinkles in the skin, reducing the visible signs of aging ( 83).
Retinol also may be useful in promoting hair growth ( 84).
18. Kale contains an ample helping of manganese.
Manganese does not get a lot of attention when it comes to minerals, but it is an important trace mineral which we all need to stay healthy.
Manganese is used to manufacture connective tissue, bones, sex hormones, and blood clotting factors.
It also helps to regulate your metabolism, including calcium absorption. It plays a role in nerve and brain function ( 86).
Kale is especially rich in manganese, containing 0.5 mg per cup. That equates to 26% of your recommended daily value.
19. Kale provides you with potassium.
You now know some of the valuable nutrients that kale contains, like calcium, vitamin A and vitamin C.
But did you know that kale is also a good source of potassium?
1 cup of chopped kale contains 299 mg of potassium, which is 9% of your daily required amount.
Dietary potassium fills many important roles in the maintenance of human health.
You need adequate potassium in order to regular blood pressure, reducing the chances of developing stroke and heart disease, and to prevent bone loss and kidney stones ( 87).
Nonetheless, the Dietary Guidelines for Americans 2010 Advisory Committee found that potassium is a shortfall nutrient.
That means that most Americans are not getting enough potassium to support all these functions at the optimum level.
Eating more kale is a great way to help fill this nutritional shortfall and get back on track.
20. Kale can help to fight depression.
The omega-3 fatty acids contained in kale have been used successfully to treat symptoms of depression ( 88).
Many medications for depression have negative side effects both over the short-term and the long-term.
Omega-3 fatty acids on the other hand are well-tolerated, and produce many positive health effects.
This may make dietary changes such as eating more kale a good approach to treating depression, whether as a standalone method or as a supplementary therapy.
Are There Any Reasons Not to Eat Kale?
A couple of years ago, there was a health scare involving kale.
A number of news outlets and ezines started running stories declaring that kale was a source of poisoning.
Immediately, a lot of people freaked out about kale.
But it is important to know that these news stories were all referencing a feature story on a magazine called Craftsmanship.
This is the story in question.
While this story is of interest, there are a few things which are important to note about it:
- It does not reference or feature peer-reviewed research.
- It also does not reference any guidelines from the government.
The article concerns an unaffiliated scientist named Ernie Hubbard, who works at an alternative health clinic.
After conducting his own research, Hubbard concluded that kale "hyperaccumulates" a heavy metal called thallium, and that this poses a health risk.
The biggest problem here is that Hubbard may have established correlation, but correlation does not equal causality. Causality has not been established.
A nutritionist named Joshua Nachman who works at the Johns Hopkins Integrative Medicine and Digestive Center has commented on Hubbard's research, stating, "His study was not the industry standard randomized controlled trial, nor was it designed to be that way.
As such, his results should not attempt to be extrapolated to the general population as that would be a non-scientific use of his valuable data."
It should also be noted that the experiments that Hubbard conducted covered only a small group of participants, and as a result, simply do not provide enough information to establish statistical significance.
Interestingly enough, the Craftsmanship article also cited a study ( 85) from 2006 which did show that kale can accumulate thallium.
Reportedly, however, the researcher who ran that very study contacted Vox (which also ran an article on this topic) to explain that he did not believe it likely that the accumulated thallium would be toxic to humans. He also said that the type of soil used to grow the kale is relevant.
The bottom line here is that this is a case of bad reporting online.
All too often, websites run headlines which are intended to get clicks and go viral, but they do not think about the damage those headlines could do to public health.
Is the potential accumulation of heavy metals in kale worthy of further investigation? Yes.
But does Hubbard's study provide enough evidence to warrant widespread panic and avoidance of kale? No.
Do you cook with canola oil? Hopefully not, because canola oil is one of the most unhealthy oils you can cook with, but plenty of people do, every day.
Canola oil is also an accumulator of heavy metals (again according to the researcher who ran the 2006 study on kale).
On the topic of health scares, there are also some people who claim that kale can cause hypothyroidism.
While kale does contain molecules called "goitrogens" which the thyroid may absorb in place of iodine, current research does not indicate that kale in any way causes hypothyroidism.
Kale has numerous health benefits which are well-demonstrated through scientific studies.
Being as there is no statistically significant evidence linking kale with poisoning or thyroid issues at this point and there is plenty of evidence that does indicate it can improve numerous aspects of health, kale remains an excellent choice for healthy eating.
Buying and Storing Kale
Kale has become a very popular vegetable, and as such, it should be easy to find in the produce section of your local grocery mart.
You will find two varieties of kale: regular kale and organic kale.
It is a wise idea to spend a little extra if necessary to purchase organic kale.
Why? Organically grown kale is more likely to have been planted in safe, healthy soil and will not have been treated with harmful chemicals.
This means it is less likely to be contaminated with toxins.
The kale you purchase should have a deep color and should be strong. The stems should be moist.
If you find yellowish or brownish leaves or a dry stem, put it back and look for another. Also do not buy kale that has little holes in it.
Once you have your kale, you should wash it at home, making sure that all dirt is rinsed away.
Dry off the kale, cut off the hard stems, and then bundle up the leaves inside a dry piece of paper towel.
Put this inside a plastic bag. Do not close it.
Store the bag with the paper towel and kale inside your fridge's crisper drawer.
Check your kale now and again to make sure it has not gotten wet.
You can store fresh kale like this for up to four days. If you wish, you can also freeze kale.
A Few Simple Kale Recipes
Now that you know all about kale, you probably are wondering how you can introduce more of this leafy green vegetable into your diet.
Here are a few quick and easy kale recipes for beginners!
1. Garlic Kale
Here is a delicious kale recipe which makes a great side dish to accompany any meal. Only three ingredients are needed!
Ingredients: Directions:- Chop up your kale into pieces that measure approximately an inch.
- Put a skillet over medium heat. Add the olive oil.
- Stir the garlic in and wait for it to sizzle (takes about 1 minute).
- Add the kale and cover it.
- Cook for the next 5-7 minutes. Now and again, remove the lid and stir the kale so that it cooks evenly. When it is bright green in color, it is done. It should be just slightly tender.
Even though this recipe is simple, it is delicious, and will make kale the next sensation at your dinner table!
2. Kale and Strawberry Smoothie
Looking for something cool and refreshing which can also give you a bit of a boost? Give this delicious kale and strawberry smoothie recipe a try.
Ingredients:- 1 cup of chopped kale
- 1 ½ cups of frozen strawberries
- 1 coconut
- 1 cup of ice
- 2 tablespoons of hemp seeds
- ½ cup cashews
- 2 drops of strawberry extract
- Optional: 1 tablespoon of maple syrup (if you prefer, you can substitute coconut nectar or another natural sweetener)
- Remove the meat from the coconut, reserving the water.
- Combine the kale with the strawberries, hemp seeds, coconut meat, maple syrup, strawberry extract, cashews and ice. Put all these ingredients together in a blender.
- Blend on high.
- If the mixture is thicker than you want, add some of the coconut water until you get the texture you are after.
- If you want the smoothie to be colder, you can add more ice.
As you might guess, kale blends deliciously with quite a few different ingredients, so be creative and try other kale smoothie recipes if you like this one!
3. Baked Kale Chips
Baked kale chips are all the rage right now in health food stores, but they are quite expensive to buy.
But did you know you can make them yourself with just a few simple steps and ingredients?
Ingredients:
- 1 bunch of kale
- 1 tbsp olive oil
- 1 tsp seasoned salt
- Preheat your oven to 350 degrees Fahrenheit.
- Line a cookie sheet (non-insulated) with baking paper.
- Cut the kale leaves from the stems and discard the stems.
- Tear up the kale leaves so that they are bite-sized.
- Season the kale leaves with olive oil and salt to your liking.
- Bake the kale in the oven for around 10-15 minutes. It will be done when the edges take on a brownish color.
This recipe is great for saving money on your favorite kale snack!
Bottom Line
Kale has a number of health benefits. It's one of the most nutrient-rich vegetables and provides fiber and protein to keep you satisfied.
It's also a versatile food. You can rub it with olive oil and sprinkle it with salt before baking it in an oven to make chips.
Adding shredded kale to salads is a great way to make them more filling and nutritious.
Believe it or not, if you add kale to any great-tasting smoothie, you won't notice a change in flavor, but you will be able to take advantage of the health benefits.
Kale is not just a health-food fad. It's a nourishing vegetable that can be incorporated into your diet in many ways