[Effects of sodium chloride on bone health]

This paper discusses the physiology of sodium effects on calcium metabolism and possible implications of increased salt intake on bone remodelling and bone mass. Osteoporosis is an increasing public health problem affecting more than 200 million of women around the world. The major complications of osteoporosis are fractures, which are frequently associated with high morbidity and mortality. A number of clinical, epidemiological and experimental studies aim at identifying lifestyle factors that may improve bone mass and prevent bone loss. Different nutrients are proposed to play a role in bone development during growth and in the maintenance of bone mass thereafter. However, the importance of sodium intake for bone health has not been elucidated. It is well known that high dietary sodium intake decreases renal calcium reabsorption, which in turn leads to a greater urinary calcium excretion. This effect has been demonstrated in studies in humans of all ages as well as in experimental animals. It is not clear to what extent sodium-induced calcium loss is compensated for by increased intestinal calcium absorption. It is suspected that, if not fully compensated, sustained hypercalciuria due to increased sodium intake may diminish bone mass. Postmenopausal women showed that increased dietary salt may indeed augment bone resorption. Sodium effects on bone mass in various studies are inconsistent and there is still no evidence that increased salt intake is a risk factor in the aetiology of osteoporosis A randomized longitudinal study of different sodium intake in two groups of subject could clarify the role of sodium in bone mass.