Greens cooked with bacon makes a traditional Southern side dish.

RODLAE NEWS, EMMAUS, PA—In-season and flavorful, leafy winter greens are truly unparalleled when it comes to nutrition. When the Center for Science in the Public Interest ranked nearly 85 vegetables in order of highest to lowest nutrient content, kale, spinach, collard greens, turnip greens, Swiss chard, and spinach were the top six. Mustard greens were at number eight. These leafy winter vegetables top the chart because they're loaded with vitamin K and lutein, in addition to containing calcium, fiber, folate, iron, and vitamin C.

Vitamin K plays a role in blood clotting; keeping vitamin K levels stable is especially important for people taking blood-thinning medication. And research has revealed that men (but not women) who took 500 micrograms of vitamin K daily over three years were less likely to develop insulin resistance. More research is needed to determine if vitamin K can keep the body sensitive to insulin, fending off diabetes, but it's one more reason to fill up on spinach, kale, and other green winter vegetables.

These leafy green wonders are also an excellent source of the carotenoids lutein and zeaxanthin. The two pigments accumulate in our eyes' retinas, protecting them by absorbing damaging light. Just 1½ servings daily of lutein- and zeaxanthin-rich foods have been shown to reduce the risk of age-related macular degeneration by 50 percent. Lutein and zeaxanthin may also help prevent non-Hodgkin’s lymphoma in men.

While spinach probably already ends up in your grocery cart, now's a great time to branch out and try fresh kale, Swiss chard, collards, and other less-familiar leafy green winter vegetables. They grow well in cooler weather, and many varieties get sweeter as the weather gets colder. The Rodale Recipe Finder is full of great ideas for preparing winter greens. Read on and try some of these recipes now to reap the many benefits of these veggie superstars.