B-complex vitamins are superstars, even though some other celebrity vitamins tend to overshadow them (we're looking at you, vitamin D). Without them, you'd have an awfully hard time getting energy from carbs, your nervous system would be all out of whack, and your hair, eyes and liver would be sickly.
Biotin, a B vitamin that's confusingly also referred to as vitamin H, is also important for healthy skin -- and embryonic development [source: University of Maryland Medical Center].
Unless you have certain medical conditions, you get plenty of biotin from your diet and your own intestines, where a bacteria factory produces it. But pregnant women do sometimes have a biotin deficiency. This fact, taken with the vitamin's importance in maintaining healthy skin, has led some to believe that giving supplements to a nursing mom can help treat cradle cap.
A big "however," though -- there's next to no evidence that it works [source: NYU Langone Medical Center]. But if you're desperate for remedies, you can discuss it with your doctor and see if there's any harm in popping a few pills.