One vitamin you should seriously consider stocking up on is Vitamin B. Vitamin B is the one vitamin that has a very big impact on the amount of energy you have and the rate of speed of your metabolism. Of course, Vitamin B is subdivided into smaller categories – Vitamin B1, B2, B3, B5, B6, B7 and B12 and Folic acid. Some B vitamins help cells burn fats and glucose for energy. Others help make neurotransmitters like serotonin. And some B's assist with the production and repair of DNA.

You can get B vitamins from proteins such as fish, poultry, meat, eggs, and dairy products. Leafy green vegetables, beans, and peas also have B vitamins. Many cereals and some breads have added B vitamins. However, many of us don't get enough B's; according to the USDA, deficiencies in Folic acid, B12, and B6 are especially common.

Ensuring that your diet contains plenty of B-rich foods –dark-green vegetables, protein from animal sources, and whole grains– is critical. If your stress level is high or if your diet is low in B's, you'll benefit from the higher amounts found in supplements.