The term vitamin B complex refers to all water-soluble vitamins except ascorbic acid. This combination of vitamins is important to prevent or treat vitamin deficiency. This lack of nutrients can be caused by certain illnesses, poor diet, alcoholism, or during pregnancy.
There are eight B vitamins: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folate), and B12 (cobalamin). These vitamins all share some characteristics, but are all unique and needed to support a healthy body. B vitamins are found in many foods, but a supplement is necessary for some people.