Getty Images

In a recent study, women who took 80 milligrams of iron daily had a 48% drop in fatigue. They were otherwise healthy people whose iron levels were on the lower end of normal. If you're tired all the time, ask your doc to check your levels. (Note: too much iron can be toxic, though. So consult an MD before adding it as a supplement.)

Vitamins: What to Take, What to Skip

12 Mental Tricks to Fight Depression

8 Tips to Instantly Boost Your Energy

12 Mental Tricks to Fight Depression

8 Tips to Instantly Boost Your Energy