The name "Vitamin B-complex" is referred to all of the known essential water-soluble vitamins except for vitamin C. The group of B Vitamins includes the following most popular vitamins: thiamine (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), pantothenic acid (vitamin B5), pyridoxine (vitamin B6), biotin, folic acid and the cobalamins (vitamin B12).

The structure of each B-complex member is unique and performs unique functions in the human body. Vitamins B1, B2, B3, and biotin participate in different aspects of energy production, vitamin B6 is essential for amino acid metabolism, and vitamin B12 and folic acid facilitate steps required for cell division. Each of these vitamins has many additional functions.