B vitamins

B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. They are a chemically diverse class of compounds, but are associated in diet, often occurring together in the same foods. Dietary supplements containing all eight are referred to as a vitamin B complex. Individual B vitamins are referred to by B-number or by chemical name, such as B₁ for thiamine, B₂ for riboflavin, and B₃ for niacin, while some are more commonly recognized by name than by number, such as pantothenic acid (B₅), biotin (B₇), and folate (B₉).

Each B vitamin is either a cofactor (generally a coenzyme) for key metabolic processes or is a precursor needed to make one.