Kale is a popular cruciferous vegetable containing a variety of nutrients and is known for contributing several health benefits to the body. This green, leafy plant has been coined a “superfood” and is a descendant of the Brassicaceae family. Different varieties of kale include curly kale, ornamental kale, Redbor kale, Russian kale, Siberian Kale, Chinese kale, and dinosaur kale, all of which differ in texture, taste, and color.
Kale is believed to have originated in eastern Turkey and was eventually brought to Europe during the first millennium (1). Kale also spread in ancient Rome and was a common food eaten by peasants in the middle ages.
Kale has become a common household vegetable and its popularity has grown in the US over the last several years. This plant can be eaten raw or cooked and is a versatile ingredient in the kitchen. In addition to its versatility in cooking, kale is extremely nutritious and contains a plethora of vitamins and minerals.
Table of Contents
- Kale Health Benefits
- 1. Kale is Packed With Nutrients
- 2. Kale Has Anti-inflammatory Properties
- 3. Kale May Reduce the Risk of Developing Heart Disease
- 4. Kale May Help Prevent Type 2 Diabetes
- 5. Kale May Have Cancer Fighting Properties
- 6. Kale is Beneficial for Eye Health
- 7. Kale Helps Promote Bone Health
- 8. Kale Helps Promote Immune Health
Kale Health Benefits
Kale has been around for centuries and has become a popular vegetable in the kitchen. There are different types of kale and a variety of ways to eat it. Let’s have a look at the several health benefits of this nutrient-dense vegetable.
1. Kale is Packed With Nutrients
Kale is packed with an abundance of nutrients. Roughly one cup of raw kale provides 4.4 g of carbohydrates, 2.9 g of protein, and 4.1 g of fiber. It also renders an abundance of iron, folic acid, calcium, and vitamin C than other foods high in those nutrients. One cup of raw kale contains around 52.3 mg of calcium, 0.33 mg of iron, 19.2 mg of vitamin C, and 12.8 µg of folate. Not only is kale nutrient-dense, it is also low in calories yielding around 33 kcals for one cup of raw kale (1, 2).
Kale is also loaded with other vitamins and minerals necessary to prevent chronic disease and allow the body to thrive. Along with calcium and iron, kale is also packed with other important minerals which include magnesium, phosphorus, potassium, sodium, zinc, copper, and manganese, all of which are vital for heart, bone, and immune health. Other important vitamins that kale yields include vitamin A, vitamin K, and vitamin E (2).
Summary: Kale is packed with vitamins and minerals and is low in calories. Kale contains nutrients that are beneficial in preventing health issues and provides nutrients that promote heart, bone, and immune health.
2. Kale Has Anti-inflammatory Properties
Antioxidants are important for protecting the body against free radicals, which may contribute to heart disease and cancer. Free radicals are the result of environmental toxins, cigarette smoking, chemicals, air pollutants, and/or normal metabolic processes, all of which attack and damage DNA, proteins, carbohydrates, and lipids. Antioxidants contain anti-aging and anti-inflammatory compounds that help combat free radicals, or toxins, reducing the risk of developing chronic diseases (3, 4).
Kale contains antioxidant properties which include vitamin C, β-carotene, flavonoids, and polyphenols. Studies show that eating kale raw is more beneficial for antioxidant purposes, primarily due to the destruction of nutrients during the cooking process (5). Kale is also high in hydroxycinnamic acids and flavonoid glycosides (quercetin, kaempferol, caffeic, ferulic, and sinapic acids), which are phenolic compounds that are effective antioxidants. These compounds have been proven to impede the effects of oxidative damage on DNA, proteins, and lipids by stabilizing free radicals (1).
Consuming antioxidant nutrients like vitamin C, phenolic compounds, vitamin E, and carotenoids supply the body with a defense against free radicals and oxidative stress, providing protection against the development of cancer, diabetes, and cardiovascular disease. Free radicals cause cell damage, resulting in inflammation and a higher risk for chronic disease. Brassica vegetables, which include kale, broccoli, cabbage, Brussels sprouts, and cauliflower contain these dietary antioxidants that are beneficial for fighting against oxidative damage (4, 5).
Summary: Kale contains antioxidants that help combat oxidative damage and aid in preventing chronic diseases, including cancer, diabetes, and heart disease.
3. Kale May Reduce the Risk of Developing Heart Disease
Besides its high antioxidant content, kale contains other nutrients that are important for reducing the risk of heart disease, cancer, diabetes, and other chronic diseases. Kale’s antioxidant content may be beneficial in reducing inflammation, combating free radicals, and protecting cells from cardiogenic damage, which may result in a reduced risk of heart disease and cancer (3, 6, 7).
Studies show that kale contains various nutrients that may be beneficial in supporting heart health. Kale can help decrease cholesterol levels due to its bile acid sequestrants which aid in limiting the amount of total cholesterol in the bloodstream (8). Additionally, kale is high in fiber. Eating foods containing fiber has been linked to reduced blood pressure and blood lipid levels, resulting in decreased LDL cholesterol (9).
Summary: Kale contains nutrients that may help support heart health and lower blood pressure. Kale contains nutrients that help decrease cholesterol and is also high in fiber, which has been linked to reduced blood pressure.
4. Kale May Help Prevent Type 2 Diabetes
Consuming fiber is not only beneficial to heart health, but it is also advantageous in reducing the risk of developing type 2 diabetes. According to a meta-analysis review, consuming large amounts of dietary fiber resulted in decreased blood glucose levels which may prevent the risk of developing type 2 diabetes (10).
Summary: Fiber is important for maintaining blood glucose levels and helping to prevent developing type 2 diabetes. Since kale is abundant in fiber, consuming kale may help promote stable blood glucose levels.
5. Kale May Have Cancer Fighting Properties
Not only does kale provide benefits to heart health and reduce blood lipid levels, this leafy green also contains cancer-fighting substances and may help reduce the risk of cancer. Due to their high content of glucosinolates, indoles, and isothiocyanates, cruciferous vegetables have been linked to a lower risk of lung and colorectal cancer. While studies do suggest a strong correlation between reduced cancer risk and cruciferous vegetables, more research is necessary to make a comprehensive conclusion (11, 12).
Kale also contains carotenoids, which have been shown to demonstrate cancer-preventative qualities by causing cell arrest and cell death (apoptosis) in prostate cancer (1).
Furthermore, kale has been used to help treat other health disorders, which include gastric ulcers, rheumatism, and hepatic diseases (1).
Summary: Kale contains nutrients that help support heart health, lower blood lipid levels, and may help decrease the risk of cancer. It is especially beneficial due to its high fiber content. While there are several strong claims that link cruciferous vegetables to reduced cancer risk, more studies need to be done in order to come to a conclusion.
6. Kale is Beneficial for Eye Health
Kale contains large amounts of lutein and zeaxanthin, which work together as an antioxidant network to promote eye health. Consuming these nutrients has been shown to decrease the risk of certain eye disorders, such as age-related macular degeneration and cataracts (13, 14).
Kale also contains vitamin C and vitamin E, two nutrients that work to support eye health (15, 16).
In addition to vitamins C and E, kale is also abundant in β-carotene, which has been shown to be beneficial for antioxidant and immunomodulatory activities, which may result in preventing cataracts and macular degeneration. Lutein and β-carotene play a role in photoprotection, serving as a light screening. Studies show that the intake of lutein supplements may improve visual function (14). Furthermore, a study done with an oil-based kale extract dramatically increased the optical density of the macular pigment, improving vision in AMD patients (1).
Summary: Kale contains high amounts of lutein and zeaxanthin, as well as vitamin C and vitamin E which help support healthy eye function.
7. Kale Helps Promote Bone Health
Kale is high in vitamin K, a nutrient that is necessary for bone health. Vitamin K helps regulate bone reabsorption, as well as plays a role in other essential functions in bone health (17).
Vitamin K plays an important role in bone strength and decreased intake of this nutrient is associated with under-carboxylation of osteocalcin and osteopenia, as well as a higher risk of bone fracture. The RDA for vitamin K is 90 µgm for women and 120 µgm for men. Just one cup of kale provides 499 µgm (18).
In addition to vitamin K, kale also contains a good amount of calcium. Calcium is vital to bone health and proper bone formation (19).
Kale is also abundant in phosphorus and magnesium, both of which are vital to bone health. The RDA for calcium is 1,200 mg/day, however, the average daily intake is far less in older populations and females. Low intake of calcium is associated with a higher risk of bone fractures, so adequate intake of calcium is important. Kale yields around 179 mg/cup, providing a healthy amount of calcium per serving (18).
Summary: Kale contains high amounts of vitamin K, as well as calcium, two nutrients that are essential for bone health and healthy bone formation.
8. Kale Helps Promote Immune Health
Vitamin C is an important nutrient in promoting immune health. Due to its high antioxidant content, vitamin C helps ward off environmental oxidative stress by assisting in the elimination of oxidant activity on the skin. Additionally, vitamin C helps aid in microbial killing, reducing the risk of infection. A deficiency of vitamin C poses an increased risk of infections and impaired immunity. Vitamin C’s ability to strengthen certain immune cell functions enables it to help prevent and treat respiratory and systemic infections (20).
The RDA for vitamin C is 75 mg for women and 90 mg for men. For certain populations like older adults and pregnant women, the RDA is increased. Just one cup of kale yields 19.6 mg of vitamin C. Not only is vitamin C important for helping infections, it is also viable for healing wounds and is essential for making collagen (21).
Summary: Kale is a great source of vitamin C, which helps promote immune function, treat wounds, and control infections.
Kale has several health benefits and provides a plethora of nutrients the body needs in order to function properly and prevent unwanted health conditions. Kale has been around for centuries and has been named a “superfood” due to its high nutrient content and beneficial health properties. Kale is known for its high antioxidant content, which is important for combating free radicals that cause cell damage. The main antioxidants found in kale are vitamin C, β-carotene, flavonoids, and polyphenols. Kale also contains other important compounds that are essential for antioxidants used to stabilize free radicals. Antioxidants are important for anti-inflammatory purposes and help to prevent the risk of developing chronic diseases such as heart disease, cancer, diabetes, and other chronic health conditions.
Not only does kale provide beneficial nutrients for preventing chronic diseases, it also contains lutein and zeaxanthin, which are nutrients that are helpful for supporting eye health and decreasing the risk of age-related macular degeneration and cataracts. Additionally, kale is high in vitamin K and contains calcium, magnesium, and phosphorus, all of which play an important role in overall bone health. Furthermore, due to kale’s high vitamin C content, kale is an excellent source for boosting immunity and fighting infections.