Kale, collard greens, turnip greens, and mustard greens are nutritionally supercharged and bursting with plant chemicals that medical studies indicate we should consume to prevent cancer, heart disease, and even vision problems.
Ruffly bluish-green kale leads the leafy group in phytochemicals -- the substances that give plants color, flavor, and health-boosting abilities. Researchers are constantly uncovering more health benefits of these plant chemicals. For instance, the hefty load of lutein in kale is linked to a reduced risk of eye problems. Other components of kale make it a cancer-fighting vegetable, especially against cancers of the colon, stomach, lung, and breast. Kale also is high in vitamin A, has almost as much calcium as milk, and contains a burst of potassium.
Before cooking kale, wash it well. Soil likes to hide amid its ruffles. Remove tough stems, and cook leaves in a bit of boiling broth or salted water until tender -- two to four minutes -- before using in a recipe. Serve cooked kale in soups, tossed with garlic-flavored olive oil and a splash of vinegar.
Mustard greens are more tender than kale, so they can be used raw in salads. They have a zesty mustard bite. The leaves mellow with simmering. Or you can steam them, saute them, or stir-fry them.
Collard greens, like kale, are related to the cabbage family. The deep-colored leaves have an irregular shape and torn-looking edges. Cook collards as you would kale.
Turnip greens, as you probably guessed, are simply the tops of turnips. Young greens are tender enough to eat raw in salads. Mature greens should be cooked like other leafy greens. Six ounces of cooked turnip greens contain 220 mg of calcium. By comparison, an 8-ounce glass of milk has 300 mg.
Lutein in spinach travels through the bloodstream to the eye's retina, according to Tufts Center on Aging. That's good news because lutein seems to absorb the type of light that can cause macular degeneration, a leading cause of blindness among older Americans. This phytochemical, also found in other leafy greens, may prevent cataracts too. High levels of lutein in the bloodstream may prevent fatty deposits from clogging arteries, according to a study from the University of California, Los Angeles.