Green leafy vegetables are nutritional powerhouses, providing a wide range of essential vitamins, minerals and phytochemicals while being low in calories. Some of these phytochemicals may help lower your risk for cancer. You should eat at least 1.5 cups of green leafy vegetables each week as part of your recommended 2.5 servings of vegetables per day, according to the U.S. Department of Agriculture.
While iceberg lettuce is relatively low in nutrients, darker greens contain folate and vitamins A, C and K. The exact amount of vitamins depends on the type of green. A cup of raw kale will provide you with more than a day's worth of vitamins A, C and K, as well as a small amount of folate. The same amount of raw spinach contains more than 10 percent of the daily value for each folate and vitamin C as well as more than 50 percent of the DV for vitamin A and 181 percent of the DV for vitamin K. Although green leaf lettuce doesn't provide a lot of folate or vitamin C, it does contain more than 50 percent of the DV for both vitamins A and K in each cup.
Dark green leafy vegetables can also be good sources of calcium, iron and potassium. Each cup of raw kale provides 15 percent of the DV for calcium, 8 percent of the DV for iron and 14 percent of the DV for potassium. Although both spinach and green leaf lettuce also contain these nutrients, they don't contain as much as kale. To get significant amounts of minerals from many green leafy vegetables, you'll need to consume more than 1 cup of greens. This can be easier to do if you eat them cooked, as these vegetables tend to shrink quite a bit with cooking.
You'll increase your intake of phytochemicals, which are beneficial plant compounds, when you eat leafy vegetables. Green leafy vegetables contain carotenoids like lutein and zeaxanthin as well as flavonoids and saponins. Lutein and zeaxanthin help prevent damage to your eyes from ultraviolet light and may also help prevent atherosclerosis, or clogging of the arteries. Carotenoids, saponins and flavonoids all act as antioxidants, helping to keep free radicals from damaging your cells. This potentially lowers your risk for cancer.
Many green leafy vegetables can be eaten both raw or cooked, including kale, cabbage and spinach, while others, like lettuce, are mainly eaten raw. Collard greens and Swiss chard are usually eaten cooked, but you can use these and most other green leafy vegetables to make green smoothies. Toss chopped greens into soups or stews near the end of cooking, saute them with garlic and olive oil and stir in some white beans for a nutritious side, or bake kale into chips for a healthy snack. Use lettuce instead of tortillas to make wraps, or top your sandwich with arugula to give it more bite. You'll get the most nutrients from these vegetables if you serve them along with something that contains a little healthy fat, since vitamins A and K and some of the phytochemicals they contain require fat for absorption.