The beautiful leaves of the kale plant provide an earthy flavor and more nutritional value for fewer calories than almost any other food around. Although it can be found in markets throughout the year, it is in season from the middle of winter through the beginning of spring when it has a sweeter taste and is more widely available.
Kale is a leafy green vegetable that belongs to the Brassica family, a group of vegetables including cabbage, collards, and Brussels sprouts that have gained recent widespread attention due to their health-promoting, sulfur-containing phytonutrients. It is easy to grow and can grow in colder temperatures where a light frost will produce especially sweet kale leaves. There are several varieties of kale; these include curly kale, ornamental kale, and dinosaur (or Lacinato or Tuscan) kale, all of which differ in taste, texture, and appearance. The scientific name for kale is Brassica oleracea.
Curly kale has ruffled leaves and a fibrous stalk and is usually deep green in color. It has a lively pungent flavor with delicious bitter peppery qualities.
Ornamental kale is a more recently cultivated species that is oftentimes referred to as salad savoy. Its leaves may either be green, white, or purple and its stalks coalesce to form a loosely knit head. Ornamental kale has a more mellow flavor and tender texture.
Dinosaur kale is the common name for the kale variety known as Lacinato or Tuscan kale. It features dark blue-green leaves that have an embossed texture. It has a slightly sweeter and more delicate taste than curly kale.
While not as well researched as some of its fellow cruciferous vegetables like broccoli or cabbage, kale is a food that you can count on for some unsurpassed health benefits, if for no other reason than its exceptional nutrient richness. In our own website food rating system, kale scored 4 "excellent," 6 "very goods," and 10 "goods"—for a total of 20 standout categories of nutrient richness! That achievement is difficult for most foods to match.
Types of Kale
Kale can be curly, flat, or even have a bluish tint mixed in with the green. The flavors differ, so try them all. Many farmers’ markets sell several types of kale, and most major grocery stores should have at least one. If you have a garden or even just a few containers on a patio, you can grow kale. Whether you buy kale from the store or pluck it from your own backyard, look for dark, crisp leaves. When you get ready to cook or eat it, remove the leaves from the tougher stalks.
Nutritional breakdown of kale
Kale is packed with nutrition that puts it high on the list of the world's healthiest foods. Kale is a leafy green cruciferous vegetable that is chock-full of essential vitamins A, C and K as well as minerals like copper, potassium, iron, manganese and phosphorus. A cup of fresh kale has only about 40 calories but packs almost 3 grams of protein. One cup of cooked kale has over 1000% more vitamin C than a cup of cooked spinach and unlike spinach; kale's oxalate content is very low which means that the calcium and iron in kale are highly absorbable in the human digestive system.
Studies have shown that type 1 diabetics who consume high-fiber diets have lower blood glucose levels and type 2 diabetics may have improved blood sugar, lipids and insulin levels. One cup of chopped fresh kale provides about 2.6 grams of fiber.
The Dietary Guidelines for Americans recommends 21-25 g/day for women and 30-38 g/day for men.
Kale contains an antioxidant known as alpha-lipoic acid, which has been shown to lower glucose levels, increase insulin sensitivity and prevent oxidative stress-induced changes in patients with diabetes. Studies on alpha-lipoic acid have also shown decreases in peripheral neuropathy and/or autonomic neuropathy in diabetics.3 Of note, most studies have used intravenous alpha-lipoic acid and it is unsure whether oral supplementation would elicit the same benefits.3
The fiber, potassium, vitamin C and B6 content in kale all support heart health. An increase in potassium intake along with a decrease in sodium intake is the most important dietary change that a person can make to reduce their risk of cardiovascular disease, according to Mark Houston, M.D., M.S., an associate clinical professor of medicine at Vanderbilt Medical School and director of the Hypertension Institute at St. Thomas Hospital in Tennessee.2 In one study, those who consumed 4069 mg of potassium per day had a 49% lower risk of death from ischemic heart disease compared with those who consumed less potassium (about 1000 mg per day).2 High potassium intakes are also associated with a reduced risk of stroke, protection against loss of muscle mass, preservation of bone mineral density and reduction in the formation of kidney stones.2 For blood pressure, increasing potassium intake may be just as important as decreasing sodium intake for lowering blood pressure because of potassium's vasodilatation effects.
According to the National Health and Nutrition Examination Survey, fewer than 2% of US adults meet the daily 4700 mg recommendation.2 One cup of chopped fresh kale provides 329 milligrams of potassium.
Also of note, a high potassium intake is associated with a 20% decreased risk of dying from all causes.2
Kale and other green vegetables that contain chlorophyll have been shown to be effective at blocking the carcinogenic effects of heterocyclic amines, which are generated when grilling foods at a high temperature.4 If you tend to like your grilled foods charred, make sure to pair them with green vegetables to help negate these effects.
Low intakes of vitamin K have been associated with a higher risk for bone fracture. Adequate vitamin K consumption is important for good health, as it acts as a modifier of bone matrix proteins, improves calcium absorption and may reduce urinary excretion of calcium.5 One cup of kale provides a whopping 550 micrograms of vitamin K, over 680% of our daily needs.
Kale is high in fiber and water content, both of which help to prevent constipation and promote regularity and a healthy digestive tract.
Healthy skin and hair: Kale is high in vitamin A, a nutrient required for sebum production to keep hair moisturized. Vitamin A is also necessary for the growth of all bodily tissues, including skin and hair.
Adequate intake of vitamin C, which kale can provide, is needed for the building and maintenance of collagen, which provides structure to skin and hair. Iron-deficiency is a common cause of hair loss, which can be prevented by an adequate intake of iron-rich foods, like kale.
Healthy skin and hair:
Kale is high in vitamin A, a nutrient required for sebum production to keep hair moisturized. Vitamin A is also necessary for the growth of all bodily tissues, including skin and hair.
Adequate intake of vitamin C, which kale can provide, is needed for the building and maintenance of collagen, which provides structure to skin and hair.
Iron-deficiency is a common cause of hair loss, which can be prevented by an adequate intake of iron-rich foods, like kale.
How to incorporate more kale into your diet
Kale, pinenut and cranberry salad Kale can be enjoyed raw in salads or on sandwiches or wraps, braised, boiled, sautéed or added to soups and casseroles.
A member of the mustard family, kale has a spicier and more pronounced flavor than your typical lettuce. It is also heartier and crisp with a hint of earthiness.
Kale grows well in the colder winter months, so can be a great addition to your fruit and vegetable routine when other produce is not as readily available.
Kale can be enjoyed raw in salads or on sandwiches or wraps, braised, boiled, sautéed or added to soups and casseroles.
Sauté fresh garlic and onions in extra-virgin olive oil until soft. Add kale and continue to sauté until desired tenderness.
Kale chips: Remove the ribs from the kale and toss in extra-virgin olive oil or lightly spray and sprinkle with your choice or a combination of cumin, curry powder, chili powder, roasted red pepper flakes or garlic powder. Bake at 275 degrees Fahrenheit for 15-30 minutes to desired crispness.
In a food processor or a high-speed blender, add a handful of kale to your favorite smoothie for a nutrient blast without a big change in flavor or try this Green Pumpkin Pie Smoothie.
Photo Gallery of Kale: