Spinach
Spinach is a leafy green flowering plant native to Central and Western Asia. The leaves can be consumed raw or cooked; fresh or after using a set of various preservation techniques, like canning or freezing. Spinach contains a certain amount of calcium and iron however it also contains oxalate, which may inhibit the absorption of the mineral. Cooking spinach, especially by steaming, can lower the amount of oxalate though cooking it can also lower the amounts of vitamin C as vitamin C degrades when in contact with heat.