Vitamins can be divided into two groups: water-soluble vitamins and fat-soluble vitamins. Water-soluble vitamins include vitamin C and the B vitamins (folate, thiamine, riboflavin, niacin, pantothenic acid, biotin, vitamin B6, vitamin B12).[6] Most dialysis patients will need to supplement vitamin C and B vitamins to replace what is lost in the dialysis solution.[7] Fat-soluble vitamins include vitamins A, D, E, and K.[8] Excessive amounts of these vitamins can be harmful for people with kidney failure because they can build up in the body and become toxic so they are not generally supplemented in dialysis patients.