Spinach is a nutritional powerhouse. In addition to being high in iron, it contains high levels of vitamins B and C, as well as antioxidants like beta-carotene (which the body converts to vitamin A) and lutein. Spinach also is a good source of minerals, including magnesium and zinc [source: Seay].
If you're selecting canned or frozen spinach at the local supermarket, you don't need to employ a lot of strategy to find the right one. Simply check the expiration date, compare the price and make a decision. Fresh spinach, however, requires a bit more consideration. Fresh spinach should be consumed at the height of its color, so look for taut upright leaves with a deep, viridian hue -- the lush sort of green that brings to mind rainforests and leafy canopies. Then, turn a few of the leaves to make sure they are free of bruises, abrasions or yellowed areas.
Keep in mind that spinach is often grown in sandy soil, so unless you're purchasing the prewashed kind, you'll need to briefly soak the leaves in cold water, swish them around and then empty the bowl of debris. After a few rounds of this, you should have clean spinach at your fingertips [source: Beck]. Fresh spinach loses nutrients every day it is stored in the refrigerator so you may not want to buy more than you can consume quickly [source: Science Daily].
If you're using spinach as an ingredient when cooking, you'll need to pay attention to whether the recipe calls for fresh, canned or frozen. Fresh spinach is 92 percent water, which means you'll need a lot more of it to equal the same amount as a can of spinach [source: University of Kentucky]. This explains the differences in iron content in our list on the previous page. However you elect to ingest it there's a simple truth about spinach: It's good for you.