Chances are, you've probably heard of the nutrient iron before. As a kid, you may remember the not-so-pleasant finger pricks at the doctor's office to check your iron levels, and as an adult, iron levels may have come up in conversations as a reason for low energy levels. But exactly what is iron? What does it do and why do you need it? Here we take a deep dive into why this nutrient is so important for your health, as well as the best food sources of iron, so you can make sure you're getting enough.