Researchers have identified at least 13 different flavonoid compounds in spinach that function as antioxidants and as anti-cancer agents. Spinach is an excellent source of vitamin C and vitamin A. These two nutrients are important antioxidants that work to reduce the amounts of free radicals in the body. Spinach is also an excellent source of folate. Folate is needed by the body to help convert a potentially dangerous chemical called homocysteine that can lead to heart attack or stroke if levels get too high, into other benign molecules.