Spinach, a dark leafy green, provides protein, iron, vitamins and minerals with most of its calories being protein. In the vitamin and mineral category, Spinach has: vitamin A, C, E, K, niacin, and folic acid; magnesium, manganese, iron, calcium, potassium, copper, and phosphorus …. shall we continue, why not, zinc and selenium, not to mention omega-3 fatty acids. Whew! This is why JOJ is a big fan of juicing spinach.