Proven Health Benefits of Kale Including Nutrition Facts (Science Based)
Kale is a green leafy vegetable that is low in calories and is packed with an amazing array of nutrients. Kale is truly a superfood because it contains high levels of vitamins, minerals, fiber, and is virtually fat-free. Consuming more kale in your diet is good to help keep your heart healthy, improve your digestive health, reduce inflammation, and help you lose weight.
There are many ways to eat kale as part of a healthy, well-balanced diet. You can eat kale raw, and you can also steam, blanch, or sauté kale leaves to tenderize the leaves while retaining its nutritional value.
Quick cooking preserves kale’s nutrients, texture, color, and flavor. Rinse kale, chop it finely to ensure rapid cooking, and add it soups, stews, stir-fries, salads, egg dishes, or casseroles. You can steam kale for 5 minutes to make it more tender or simply eat it raw. You can also splash on the kale a little bit of lemon and olive oil to enhance its health-promoting qualities.
Kale is also sold in a powder form which can be added into water, juices, smoothies or sauces, as well as in capsule form. You can even use kale as an ingredient in another fermented food such as sauerkraut or kimchi.
In this article, you will learn what scientific research says as to the many reasons why a serving of kale is good for you. You will also find out about the nutrients that make kale such a great food to enjoy regularly.
What is Kale and What Makes It a Superfood?
Kale is a cruciferous vegetable from the Brassica oleracea species of plants, and is in the same family as cabbage and broccoli.
There are many types of kale, and the shape and color of kale leaf determine the variety.
Researchers from Harvard School of Public Health report that the most common types of kale are Tuscan kale (lacinato kale) and curly kale. These kale varieties generally have dark-green leaves that have a somewhat slightly bitter taste. (1)
Other types of kale include red kale and black kale. Some varieties of kale have purple-red leaves, deep purple leaves, or bluish-green leaves in varying shapes and sizes.
Many people say that raw and blanched kale have a slightly bitter taste. Sautéing, frying in oil with garlic, or blanching are different ways to cook kale and soften the leaves. You can remove the tough stem from the kale leaves, roll them up or rub them together to soften them, slice thinly and add lemon juice and olive oil to make them taste better.
Different types of kale also have different tastes. For example, comparing green kale and red kale, you may find that red Russian kale has a sweeter, milder taste.
Doctors from WebMD explain that the reason kale is a superfood is due to its rich vitamin and mineral content. Kale contains most of the nutrients you need daily to strengthen your immune system and improve your health. For example, one cup of chopped kale leaves contains more than enough vitamins A, C, and K for your daily needs. (2)
Kale Nutrition Facts (Calories, Protein, Fiber, Carbs, Vitamins)
When studying the nutritional content of kale, it becomes easy to see why kale is a superfood.
One serving of kale is approximately one cup of chopped kale weighing 67 grams. A cup of kale contains just 33 calories and virtually no fat at all. The same serving size of kale also gives you 1.3 grams of dietary fiber which is 5% of your recommended daily intake (RDI), and 2.2 grams protein (4% RDI). (3)
Kale also helps keep your immune system, skin, and blood healthy because of its high vitamin content. Consuming 50 grams of chopped kale provides your body with 67 mg of vitamin C which meets your daily requirements. In fact, gram for gram, kale contains double the amount of vitamin C than an orange. (4)
One cup of kale also gives you 547 mcg of vitamin K which is nearly 7 times the amount you need each day. Researchers say that vitamin K is necessary to help keep your blood healthy, assist in blood clotting, strengthen bones, and help prevent cancer. (5)
Because vegetables rich in vitamin K such as kale affect your blood, doctors from the Mayo Clinic recommend avoiding consuming large amounts of kale if you take blood thinners like warfarin. (6)
Kale is also good for your vision, a healthy immune system, and helping to maintain internal organ health because of its vitamin A content. (7) 100 grams of kale contains 15,376 IU vitamin A which is 308% of your RDI. From this, kale contains 9 mg B-carotene which is necessary for preventing vision loss and keeping skin looking healthy. (8)
In some ways, kale is better for you than spinach. For example, kale contains more vitamin A, vitamin K, and vitamin C, as well as being a better source of calcium than spinach. (36) Also spinach has a higher level of oxalates, and if you tend to form calcium oxalate kidney stones, your doctor may recommend restricting foods rich in oxalates, such as spinach. (41)
Another reason why kale is extremely good for you is that it contains high levels of essential minerals. The United States Department of Agriculture reports that 100 grams of kale contains 254 mg of calcium (25% of RDI for an adult) which the body can easily absorb. (4, 9, 41)
The mineral content of one cup of chopped kale (67 g) also includes 0.5 mg manganese (26% RDI), 0.2 mg of copper (10% RDI), 300 mg of potassium (9% RDI), and 22.8 mg magnesium (6% RDI).
Kale is also low in carbs and is a great, healthy vegetable if you are on a keto diet. Although kale has slightly more carbs than broccoli and spinach, there are only 6.7 grams of carbs in a cup of chopped kale.
Kale is also a good source of the type of iron called non-heme iron, or, iron from non-meat sources. 100 grams of kale contains 1.6 mg of iron which is just slightly less than ground beef. (4, 10) Non-heme iron is poorly absorbed in the body. However, consuming vitamin C with kale will help your body to absorb more iron from kale. (11)
Kale is packed with antioxidants
Cruciferous leafy vegetables such as kale are good for your health because they contain powerful antioxidants in the form of phytochemicals.
The Journal of Agricultural and Food Chemistry reports that curly kale has flavonoids such as quercetin and kaempferol. (12) These antioxidants are important for reducing inflammation, protecting your heart health, and preventing DNA cell damage. (13, 14)
Vitamin C, beta-carotene, and vitamin E are also important antioxidants found in kale. Scientists recommend lightly blanching kale to cook it to retain its antioxidants. (15)
Learn how you can add kale to delicious cancer-fighting smoothies to help strengthen your immunity.
Why Kale Can Be Bad for You
Because kale nutrition content is so great, consuming kale in salads, smoothies, soups, and other meals can help benefit your health.
Despite the fact that kale is an extremely healthy vegetable, there are some conditions where eating too much kale could be bad for you.
It may not be a good idea to eat large amounts of kale if you suffer from an under-active thyroid. Some studies report that kale is a goitrogenic food which can affect thyroid hormone synthesis. This is due to a compound in kale called goitrin. (16)
Other reports indicate that eating high amounts of cruciferous vegetable could have a negative impact on thyroid health in people who have an iodine deficiency. (17)
However, it is good to remember that kale is not toxic and it is certainly not bad for you. The journal Nutrition Reviews in 2016 reported that the amount of goitrin in kale is not enough to cause a significant risk in people with thyroid dysfunction when consumed in moderate amounts. (18)
Learn more about your thyroid hormones and about the signs of a thyroid disorder.
Can Eating Too Much Kale Be Dangerous?
Eating kale in moderate amount is not dangerous. The many health benefits of consuming kale in your diet generally outweigh any perceived risks.
Doctors generally advise against consuming large amounts of vitamin K rich vegetables like kale, spinach, broccoli, and chard if you take blood-thinning drugs. This is because the high levels of vitamin K can interact with anticoagulant medications. (6, 19)
Why Kale Can Be Really Good for You: Health Benefits of Kale
Let’s look in more detail at reasons why consuming kale is good for your heart, digestion, vision, immune system, and losing weight.
Kale Has Antioxidants that are Good for Your Heart Health
The high levels of antioxidants in kale mean you can eat raw kale like lettuce or use it in cooking to help keep your cardiovascular system healthy.
The journal Nutrients reports that green vegetables such as kale contain organosulfur compounds that are good for your heart. These compounds help reduce inflammation and help prevent the formation of plaque in your arteries. (20)
Other research has shown that a diet rich in kale, bok choy, broccoli, and other green leafy vegetables can greatly lower your risk of cardiovascular disease. Researchers found that steamed kale retained more of the cardiovascular benefits. (21)
Find out about some of the easy steps you can take to significantly reduce your risk of a heart attack.
Kale juice helps to reduce cholesterol
Consuming kale juice daily can be good if you need to lower your cholesterol levels and improve your heart health.
One study involving men with high cholesterol found that consuming 150 ml of kale juice helped lower cholesterol over a 12-week period. The scientists concluded that kale juice consumption can lower the risk of coronary heart disease in men. (22)
Learn about other delicious foods that have cholesterol-lowering properties.
Kale can help lower blood pressure
Another way that consuming kale juice is good for your cardiovascular health is that it can treat hypertension.
One study found that consuming 300 ml of kale juice daily along with meals can help lower blood pressure, cholesterol, and lipids (a type of fat in the blood). The blood pressure-lowering effect of kale was due to detoxification enzymes in kale. (23)
If you suffer from high blood pressure, find out about more natural remedies for hypertension.
Kale Helps Protect Eye Health
Kale is a superfood containing vitamins and nutrients that can prevent vision loss and age-related macular diseases.
The American Journal of Ophthalmology reported that consuming at least one serving of kale a week reduced the risk of glaucoma by 57%. Scientists noted that fruits and vegetables such as kale that contain vitamins A and C can help prevent glaucoma. (24)
Kale is a functional food that also contains carotenoids lutein and zeaxanthin that help prevent eye degeneration. One cup of chopped kale contains 26.5 mg lutein and zeaxanthin. (3)
Some studies indicate that you need at least 20 mg of lutein daily to help protect good vision. However, the average person only gets 1-2 mg of lutein daily. (25)
Scientific studies have shown that getting enough lutein and zeaxanthin in your diet can help to prevent cataracts and age-related blindness. (26)
One pilot study showed that consuming 50 ml kale extract daily can help to improve concentrations of xanthophylls (lutein and zeaxanthin) in the macula (part of your retina). (27)
When you compare the vitamin K and vitamin A content between broccoli and kale, you can see that kale is far superior to broccoli when it comes to protecting your vision health. (37)
Learn about other natural ingredients you can add to your super smoothies to help improve your eyesight.
Kale is a Natural Anti-Inflammatory Food
The high concentration of flavanols in cruciferous vegetables such as kale help to reduce inflammation in the body.
Long-term inflammation due to stress, repeated infections, or an unhealthy lifestyle can lead to chronic diseases like heart disease, diabetes, arthritis, or cancer. (28)
Researchers have discovered that antioxidants like quercetin, kaempferol, and isoquercetin have an anti-inflammatory effect. Anti-inflammatory foods can help to lower inflammatory responses and stimulate the immune system. (29)
The Nutrition Journal also listed kale leaves in its list of anti-inflammatory foods that can help to treat inflammatory bowel disease. (30)
Kale is Good for Strengthening Your Immune System
Kale is a nutrient-dense food that benefits your overall health because antioxidants and vitamins in kale leaves boost your body’s defenses against disease and infection.
One cup of chopped kale contains more than enough vitamin C, vitamin A, and vitamin K for your daily needs.
Researchers studying the health benefits of cruciferous vegetables say that enzymes in vegetables such as kale act as immunostimulants. This helps to prevent oxidative stress and help the immune system fight chronic disease like cancer. (31)
Learn about some of the best natural supplements that can help boost your immune system to keep you healthy.
Consuming More Kale May Help You Lose Weight
Eating kale on a weight-loss diet is good because kale is a low-calorie, no-fat food that contains fiber, protein, and essential amino acids.
One of the reasons why eating plenty of kale is good for weight loss is that it helps you feel full without lots of calories.
Also, studies have shown that consuming low energy foods such as kale can help assist in weight loss. (32)
Other studies have shown that increasing your intake of green leafy vegetables such as kale can help with long-term weight loss and weight management. The reason for this is that kale is among the vegetables with lots of fiber and has a low glycemic load. (33)
Kale Boosts Digestive Health Because It Contains Fiber and Prebiotics
Enjoying 3 or 4 servings of kale per week is good for keeping your digestion working. Kale is an important source of fiber that helps improve your digestive health.
Consuming a 1-cup serving of kale amounts to 1.3 g of dietary fiber which is 5% of your daily fiber requirements. Doctors from the Mayo Clinic say that fiber in green vegetables help pass stool easier through your digestive system and normalize bowel movements. (34)
There are also other reasons why kale is good for your digestion. Research has shown that kale contains prebiotic carbohydrates that help increase the number of probiotics in your gut. This helps improve the microflora of your intestinal system and boost your digestive health. (35)
If you find that consuming kale causes you to have excess gas, learn about some of the best natural methods to reduce gas and bloating.
Kale Has Anticancer Properties
Vegetables like kale have many beneficial compounds that help to fight off cancer and prevent tumor cells from spreading.
The journal Nutrition and Cancer reports that cruciferous vegetables have active compounds that have chemopreventive properties. Scientists have noted direct links between consumption of green leafy vegetables such as kale and cancer prevention. (36)
Sulforaphane extracts from cruciferous vegetables have shown to have potential in fighting cancer. (37)
Other studies point to the fact that vegetables like kale, broccoli, and other green veges have powerful antioxidants that help to kill off free radicals that can cause DNA damage to cells. (38)
Studies from as far back as 1999 have found that a high intake of cruciferous vegetables can help prevent cancer. (39)
Of course, cancer is a complex disease and there is no evidence that one specific type of food can treat cancer. However, scientists generally agree that a diet rich in fresh vegetables and fruits can help to prevent some types of cancer. (40)
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