The B vitamins are eight water-soluble vitamins that play important roles in cell metabolism. Historically, the B vitamins were once thought to be a single vitamin, referred to as Vitamin B (much like how people refer to Vitamin C or Vitamin D). Later research showed that they are chemically distinct vitamins that often coexist in the same foods. Supplements containing all eight B vitamins are generally referred to as a vitamin B complex. Individual B vitamin supplements are referred to by the specific name of each vitamin (e.g. B1, B2, B3). The B vitamins often work together to deliver a number of health benefits to the body. B vitamins have been shown to:Support and increase the rate of metabolism; Maintain healthy skin and muscle tone; Enhance immune and nervous system function; Promote cell growth and division - including that of the red blood cells that help prevent anemia; Together, they also help combat the symptoms and causes of stress, depression, and cardiovascular disease.