Fresh spinach is a nutritional powerhouse, but don't let it linger in the fridge.

The best way to use your leafy greens is during the first 4 days after purchase. After that, the antioxidant and folate levels of spinach plummet, turning it into a wimpier green.

Spinach on Ice
Even at the coldest refrigerator temperatures, researchers found that after 4 days, folate levels in a bag of fresh spinach dropped big time, and the loss escalated with each passing day. Colder temps were better for holding onto carotenoids. (Besides folate, learn what else is packed into those dark-green leaves.)

The Power of Fresh
Buying local spinach (at a farmers market or co-op store) may deliver the most nutrients to your table. Grocery-store fresh is a good second choice. Can't plan ahead? Then grab some frozen spinach. Spinach that's frozen and packaged soon after harvesting retains much of its nutritional value. (Is fresh always best, in terms of total nutrition? Find out in this article.)

Now, what do pizza, chili, and spinach have in common? Read this tip for the answer.