Biotin (aka Vitamin B7) receives most of its publicity through the use of hair, skin, and nail supplements. Despite its presence in these products, there is not much evidence that it will do anything in terms of either increasing growth or quality of any of these (sorry to burst your bubble). While inadequate biotin consumption may cause a decreased quality of hair, skin, and nails due to improper protein utilization, those are really the least of your worries if you don't get enough biotin. A supplement may help to address an insufficiency if overall diet quality is low, and that may explain the anecdotes surrounding its use in beauty pills. The RDA is set at 30 mcg per day and is quite easy to meet with normal food intake. 

Functions

  • Used as a coenzyme
  • Proper energy metabolism
  • Regulation of gene expression
  • Proper protein utilization
  • Needed for fatty acid synthesis

Primary deficiency symptoms and diseases

  • Depression
  • Loss of muscle control
  • Skin quality issues
  • Improper protein metabolism

Food sources

Something worth noting is that a protein called avidin found in egg whites can bind biotin and render it unusable by the body. Cooking egg whites destroys avidin and alleviates this concern.

  • Egg yolk
  • Peanuts
  • Almonds
  • Mushrooms
  • Tomatoes

Supplementation

As mentioned earlier, biotin supplements will likely not do much for enhancing the quality of hair, skin and nails aside from addressing inadequate intake. Despite saying this, many people will still supplement it even with a lack of evidence for its efficacy.

  • Biotin

Who needs it most?

  • Females who smoke (may experience higher breakdown of biotin)
  • Those who frequently consume raw egg whites
  • People who consume alcohol frequently
  • Those with malabsorption issues