The water-soluble vitamins include ascorbic acid (vitamin C), thiamin, riboflavin, niacin, vitamin B6(pyridoxine, pyridoxal, and pyridoxamine), folacin, vitamin B12, biotin, and pantothenic acid. Water-soluble vitamins are vitamin C and all the vitamins that start with the letter B (they're known as the B-complex vitamins or just B vitamins). Water-soluble vitamins areimportant for your brain function, immune health, energy and more