When I turned 50, I was confused: Could I still wear jeans? Do I still want sex? Will I ever be able to run in a marathon? Could I finally lose those last 10 pounds that piled on after menopause? Is this the when I become invisible? (Answers: yes, yes, yes, yes, and not a shot in hell.)

Eating healthfully is always important, but the nutrients you need most can vary by the decade. Here's your guide to what to eat and when from your 20s through your 60s and beyond.