Two main varieties of Swiss chard are found on store shelves: one with multicolored stems and veins, often called rainbow chard, and another with white stems and veins. Both are great sources of lutein and zeaxanthin, an antioxidant duo that’s good for your eyes. At only 7 calories a cup, the green giant is waistline-friendly, too. Cooking tip: To preserve its nutritional might, lightly steam chard and toss with vinaigrette. You can also use the leaves instead of tortillas when making soft tacos.