Give spinach some heat
Cooked spinach is higher in iron, calcium, and magnesium than raw spinach. The reason? Heat helps to release these minerals from compounds they are bound to so your body can absorb them better. When cooking spinach, use gentle heat, suggests Brissette. “That will keep the more delicate vitamins intact,” she says.
Tip: Steam, microwave, or use other methods that use lower heat to heat your spinach and never submerge your spinach in water.