The cholesterol-lowering ability of collard greens is its true nutritional strengths, even going beyond kale and broccoli in this area. Choose greens that have smooth, green, firm leaves. Small, young leaves are likely to be the least bitter and most tender. Collard Greens provide great nutritional value and possess little to no calories! With a huge source of soluble fiber and Vitamin C, one serving of Collard Greens contains more than your daily allotment of Vitamin K and A, and is a great source of folate, manganese, calcium and tryptophan.