Magnesium 375 (as Hydroxide, Oxide, Citrate & Carbonate) 100% NRV. Magnesium contributes to the maintenance of normal bones and the normal functioning of the nervous system. It also contributes to maintaining normal muscle function, including the heart muscle. Magnesium is also increasingly recognised as a nutrient that can contribute to a reduction of tiredness and fatigue.Magnesium is termed an essential nutrient which means we must obtain it from our diet. Each tablet provides the full adult NRV of magnesium in the form of a unique blend of 4 different magnesium compounds. This one a day tablet is an excellent partner for most multivitamin formulas.