Like other leafy greens, kale is well-known for its health-promoting qualities, including its nutrient density and antioxidant content.
A cup (67 grams) of raw kale contains plenty of B vitamins, potassium, calcium and copper.
It also fulfills your entire daily requirement for vitamins A, C and K .
It is a member of the mustard, or Brassicaceae, family, as are cabbage and Brussels sprouts.
This article looks at the nutritional content and health benefits of kale, how to include it in the diet, and reasons why some people should not eat too much of it.
Due to its high amount of antioxidants, kale may also be beneficial in promoting heart health.
In a 2008 study, 32 men with high cholesterol drank 150 ml of kale juice daily for 12 weeks. By the end of the study, HDL cholesterol increased by 27%, LDL cholesterol decreased by 10% and antioxidant activity was increased.
Another study showed that drinking kale juice can decrease blood pressure and may be beneficial in reducing both blood cholesterol and blood sugar.
Antioxidants help the body remove unwanted toxins that result from natural processes and environmental pressures.
These toxins, known as free radicals, are unstable molecules. If too many build up in the body, they can lead to cell damage. This may result in health problems such as inflammation and diseases. Experts believe that free radicals may play a role in the development of cancer, for example.
Fiber: A 2018 study concluded that people who consume the highest amounts of dietary fiber appear to have a lower risk of developing type 2 diabetes. Consuming dietary fiber might also lower blood glucose levels, the authors note.
Antioxidants: Authors of a 2012 article note that high blood sugar levels can trigger the production of free radicals. They note that antioxidants, such as vitamin C and alpha-linolenic acid (ALA), can help reduce complications that may occur with diabetes. Both of these antioxidants are present in kale.
Various nutrients in kale may support heart health.
Potassium: The American Heart Association (AHA) recommend increasing the intake of potassium while reducing the consumption of added salt, or sodium. This, say the AHA, can reduce the risk of high blood pressure and cardiovascular disease. A cup of cooked kale provides 3.6% of an adult’s daily needs for potassium.
Fiber: A Cochrane review from 2016 found a link between consuming fiber and a lower blood lipid (fat) levels and blood pressure. People who consumed more fiber were more likely to have lower levels of total cholesterol and low-density lipoprotein (LDL), or “bad” cholesterol.
People need both soluble and insoluble fiber.
Chlorophyll: Kale and other green vegetables that contain chlorophyll can help prevent the body from absorbing heterocyclic amines. These chemicals occur when people grill animal-derived foods at a high temperature. Experts have linked them with cancer.
The human body cannot absorb much chlorophyll, but chlorophyll binds to these carcinogens and prevents the body from absorbing them. In this way, kale may limit the risk of cancer, and pairing a chargrilled steak with green vegetables may help reduce the negative impact.
Antioxidants: The vitamin C, beta carotene, selenium, and other antioxidants in kale may help prevent cancer. Studies have not found that supplements have the same effect, but people who have a high intake of fruits and vegetables appear to have a lower risk of developing various cancers. This may be due to the antioxidants these foods contain.
Calcium and phosphorus are crucial for healthy bone formation.
A cup of cooked kale provides almost five times an adult’s daily need for vitamin K, around 15–18% of their calcium need, and about 7% of the daily phosphorus requirement.
Kale is high in fiber and water, both of which help prevent constipation and promote regularity and a healthy digestive tract.
Skin and hair
Kale is a good source of beta-carotene, the carotenoid that the body converts into vitamin A as it needs it.
Beta-carotene and vitamin A are necessary for the growth and maintenance of all body tissues, including the skin and hair.
The body uses vitamin C to build and maintain collagen, a protein that provides structure for skin, hair, and bones. Vitamin C is also present in kale.
A cup of cooked kale provides at least 20% of a person’s daily need for vitamin A and over 23% of the daily requirement for vitamin C.
The table below shows the amount of each nutrient in a cup of boiled kale, weighing around 118 grams (g), without added salt.
|Nutrient||Amount in 1 cup||Daily adult requirement|
|Carbohydrate in grams (g)||6.3, including 1.4 g of sugar||130|
|Calcium in milligrams (mg)||177||1,000–1,200|
|Selenium in micrograms (mcg)||1.1||55|
|Vitamin C (mg)||21||75–90|
|Folate (mcg DFE)||76.7||400|
|Betaine (mg)||0.4||No data|
|Beta carotene (mcg)||2,040||No data|
|Lutein + zeaxanthin (mcg)||5,880||No data|
|Vitamin E (mg)||1.9||15|
|Vitamin K (mcg)||494||90–120|
|Vitamin A (mcg RAE)||172||700–900|
Kale also provides a range of antioxidants and B vitamins.