Water dissolves them, and your body doesn’t store them, so most must be taken every day. They include C and the B’s: thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folic acid (B9), and cobalamin (B12). Take them with or without food, with one exception: You’ll absorb B12 better with a meal. If you also use vitamin C, put 2 hours between them. Vitamin C can keep your body from using B12.