Calcium any label, but make sure it's coupled with magnesium Calcium and magnesium are essential for proper muscle function, and the two travel as a pair, so don't take one without the other or you're wasting your money. The ratio should be two parts calcium to one part magnesium. This pair tends to relax the body and could make you sleepy, so take it before bed and sleep really well. If you are calcium depleted, your muscles will be irritable. Potassium is also important, but to a smaller extent than calcium.
Most multivitamins provide adequate potassium.
Vitamin C any label Don't go overboard with this vitamin. There has been a lot of debate in the press about using vitamin C as a home remedy. The key here is that it can be effective in moderation and anything in excess can be harmful. In fact, too much vitamin C can be dangerous. I have been told that the body can assimilate up to one gram per hour.