Kale, spinach, collard greens, bok choy, broccoli, turnip greens and many other dark green leafy vegetables are excellent sources of calcium. Okra and garlic also contain significant amounts of calcium.
One cup of cooked turnip greens contains approximately 250 milligrams of calcium, which is roughly one-quarter of the recommended daily intake. Calcium deficiency is a concern for many vegans as they do not eat dairy products, which are some of the best sources of calcium available. By rounding out their diets with these calcium-rich vegetables and other calcium-fortified foods, vegans can maintain the proper levels to keep their bones strong and help prevent osteoporosis.