Water-soluble vitamins are alike in that, with the exception of B12, they can be supplied by plants in the diet. These vitamins are not stored in the body for very long and therefore need to be consumed regularly. Primarily the water-soluble vitamins serve as coenzymes in metabolic reactions.

The majority of the water-soluble vitamins are 'B' vitamins and these play a major role in energy metabolism. The following vitamins will be described: thiamin, riboflavin, niacin, pyridoxine, folic acid, vitamin B12, and vitamin C.