Raw vs Steamed Spinach

from Oxygen April 2013 issue:

Which packs more nutrients?  As  you probably know, spinach is an excellent source of nutrients.  However, a naturally occurring compound in raw spinach called oxalic acid (sometimes referred to as oxalate) interferes with the absorption of some minerals found in spinach, including iron and calcium.  Cooking the spinach helps to break down this compound.  One cup of cooked spinach contains 6.5 milligrams of iron and 245 milligrams of calcium.  On the contrary, one cup of raw spinach only has 0.8 milligrams of iron and 30 milligrams of calcium.  Steaming is also a better cooking method than boiling, as it helps to preserve water-soluble vitamins that can be lost through the boiling process.  All you need is a maximum of five minutes over medium heat to steam a pound of fresh spinach.

Other Tidbit:  Research shows that spinach helps relax arteries and lower blood pressure, reducing the risk of heart disease.