Kale: Health benefits, nutrition, eating, and risks (original) (raw)

Kale can be good for adding fiber and antioxidants to the diet in many savory dishes, salads, and smoothies. Various health benefits include managing blood pressure and boosting digestive health.

Kale is a leafy green cruciferous vegetable that is rich in nutrients. 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.

Kale contains fiber, antioxidants, calcium, vitamins C and K, iron, and a wide range of other nutrients that can help prevent various health problems.

Diabetes

There is evidence that some of these, as found in kale, may offer protection against diabetes.

A 2018 study concluded that people who consumed higher amounts of dietary fiber appeared to have a lower risk of developing type 2 diabetes. Consuming dietary fiber might also lower blood glucose levels.

Heart disease

Various nutrients in kale may support heart health.

A 2019 report notes a potential link between consuming fiber and 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. One cup of kale contains 5.72 g of fiber.

Cancer

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. Free radicals may play a role in the development of conditions such as cancer.

Bone health

Leafy green vegetables such as kale are high in vitamin K. One cup of cooked kale contains 544 micrograms (mcg) of vitamin K. Daily adequate intake of vitamin K for adults is around 75–120 mcg.

Constipation

Kale is high in fiber and water. It may be beneficial for relieving mild constipation, and promoting 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.

Eye health

Vitamin C, vitamin E, beta-carotene, and zinc also play a role in eye health. All of these are present in kale.

The table below shows the amount of each nutrient in a cup of cooked fresh kale, weighing around 130 g, without added fat.

It also shows how much on average an adult needs of each nutrient, according to the Dietary Guidelines for Americans, 2020–2025. Requirements may vary according to the individual’s sex and age.

Kale is a crisp and hearty vegetable, with a hint of earthiness. The flavors and nutritional content can vary between types. Younger leaves and summer leaves tend to be less bitter and fibrous.

Curly kale

Curly kale is the most commonly available type. It is usually bright green, dark green, or purple, with tight, ruffled leaves that are easy to tear.

To remove the leaves from the fibrous stalk, run your hand down the stalk in the direction of growth.

Lacinato or dinosaur kale

Lacinato or dinosaur kale is a dark blue-green variety that is firmer and more robust than curly kale. It is known as dinosaur kale because of its scaly texture.

The leaves tend to be longer and flatter and maintain their texture after cooking. Less bitter than curly kale, dinosaur kale is ideal for making kale chips.

Red Russian kale

Red Russian kale is a flat-leaf variety that looks a little like oak leaves. The stalks are slightly purple, and the leaves have a reddish tinge.

People may find the stalks too fibrous to eat, but the leaves are sweet and delicate, with a hint of pepper and lemon, almost like sorrel. People can add them raw to salads, sandwiches, and juices, or as a garnish.

Other preparation and serving tips

Kale grows well in the colder winter months, making a good addition when other fruits and vegetables are less readily available.

It is best to cook winter kale, as colder weather can turn the sugars in kale into starch, increasing the bitterness and fiber content.

People can eat kale raw, or steam, braise, boil, or sautée it. They can also add it to soups and casseroles. Other serving suggestions include the following:

Raw: Scrunching the leaves briefly in the hands can make them easier to digest. Add to salads, sandwiches, wraps, or smoothies.
As a side dish: Sauté fresh garlic and onions in olive oil until soft. Add kale and continue to sauté until desired tenderness. Alternatively, steam for 5 minutes, then drain and stir in a dash of soy sauce and tahini.
Kale chips: Remove the ribs from the kale and toss in olive oil or lightly spray and sprinkle with a combination of cumin, curry powder, chili powder, roasted red pepper flakes, or garlic powder. Bake at 275°F for 15–30 minutes to desired crispness.
Smoothies: Add a handful of kale to any favorite smoothie. It will add nutrients without changing the flavor very much.

The Environmental Working Group, which assesses a range of products every year, put kale third on their 2023 list of fruits and vegetables most at risk of contamination with pesticides. People should wash kale thoroughly before using it.

Some people should avoid eating too much kale in the following cases:

Beta blockers: Doctors often prescribe this type of medication for heart disease. They can increase potassium levels in the blood as they block potassium channels. People who take beta blockers should consume high-potassium foods, such as kale, in moderation.
Kidney disease: Consuming too much potassium can be harmful to people whose kidneys are not fully functional. If the kidneys cannot remove excess potassium from the blood, consuming additional potassium can be dangerous.
Blood thinners: Kale is a rich source of vitamin K, which contributes to blood clotting. This could interfere with the activity of blood thinners, such as warfarin (Coumadin).

Here are some frequently asked questions about kale.

Is it OK to eat kale every day?

As kale contains a variety of nutrients, a person can consume it regularly as part of a balanced diet. However, some people may need to limit how much kale they consume. These include people taking beta blockers and blood thinners, as well as people with kidney disease.

What is the healthiest way to eat kale?

There are numerous ways to consume kale. A person may choose to eat kale raw, or they can boil, steam, braise, or sautée it. Kale can be a tasty side dish, and it can also add nutrients to a smoothie.

Is kale better for you than spinach?

Both kale and spinach provide a range of nutrients and offer numerous possible health benefits. A person can contact their doctor or a registered dietitian to discuss whether one would be better than the other for their specific needs.

Kale is a leafy green vegetable that provides a wide range of nutrients. Possible health benefits of kale include lowering the risk of type 2 diabetes, protecting against heart disease, and helping prevent constipation. Kale may also improve bone, skin, and hair health.

Kale is a healthful addition to a varied diet, and people can use it in numerous ways. How they prepare kale can depend on the type of kale, but they may wish to add it to salads, bake it into kale chips, and add it to smoothies.