Water See Hydration status Water-soluble vitamins Vitamins that dissolve in aqueous solvents are con-
sidered water-soluble vitamins and include ascorbic acid, thiamin, riboflavin, niacin, vitamin B6, vitamin B12, folic acid, pantothenic acid, and biotin. In general water-soluble vitamins are absorbed through the portal blood supply. Within the bloodstream, water-soluble vitamins are often transported unbound although many are also present in the blood as their coenzyme forms or bound to transport proteins. Clinical deficiency of any of the water-soluble vitamins is likely to impair athletic performance; however, research supporting a benefit for their supplementation to improve performance is scant at best.