The importance of calcium in skeletal health is well established in the scientific literature, and the nutrient’s popularity as a supplement is justifiable. More than 99% of the calcium in the body is contained in bones and teeth and hard bone is comprised of around 90% calcium. It is worth noting that calcium helps maintain bone density by more than just its role in the structural composition of bone tissue. Healthy bone tissue is not inert – it is constantly being built up and broken down in order to ensure a balance between proper skeletal integrity and blood calcium levels. Calcium stimulates the release of the thyroid hormone calcitonin, which causes calcium to be taken from the blood to replenish levels in bone tissue. This action is intended to work in balance with phosphorus, a mineral that stimulates parathyroid hormone release, which in turn causes calcium to be taken from the bone in order to elevate blood calcium levels. Rickets (involving impaired growth and bone malformation in children) and osteomalacia (soft bones in adults) are a direct consequence of a long-term deficiency of calcium in the diet. Calcium supplementation affords considerable protection to bone health, as demonstrated in numerous studies. For example, in postmenopausal women, a review of the research indicates that supplementation with 1000-1700mg per day significantly reduces the rate of bone loss and is associated with a reduced incidence of osteoporotic fractures.