Calcium, Magnesium and Vitamin D are needed for the maintenance of normal bones and teeth. Calcium, Magnesium and Vitamin D contribute to normal muscle function. Calcium and Magnesium contribute to normal energy-yielding metabolism. Calcium and Magnesium have a role in the process of cell division and specialisation. Calcium contributes to normal blood clotting, normal neurotransmission and the normal function of digestive enzymes. Magnesium contributes to a reduction of tiredness and fatigue, normal electrolyte balance, normal functioning of the nervous system, normal protein synthesis and psychological function. Vitamin D contributes to normal absorption/utilisation of calcium and phosphorus, normal blood calcium levels, and the normal function of the immune system. Vitamin D also has a role in the process of cell division. Calcium and vitamin D help to reduce the loss of bone mineral in post-menopausal women. Low bone mineral density is a risk factor for osteoporotic bone fractures.