A 1 cup serving of cooked collard greens contains 771 micrograms of vitamin A, which is slightly more than the 700 micrograms women need on a daily basis and close to the 900 micrograms men require. Vitamin A plays a role in the function of your skeletal system and the health of your eyes, skin, teeth and mucus membranes. The vitamin helps protect your cells from damage and can decrease your risk of cancer, according to the University of Maryland Medical Center.