Some mineral waters contain minerals in such high concentrations that they can influence bone health when consumed regularly. Calcium from mineral water is readily absorbed, inhibits PTH secretion and bone resorption on the short as well as on the long term. Sodium concentrations are too low to bother, sulfates have no documented bone effect, but fluoride can in rare cases be so high that it increases bone density. Since potassium and bicarbonate lower renal calcium excretion, and since the latter improves calcium balance, mineral waters rich in bicarbonate and potassium have been tested. Indeed, they lowered renal calcium excretion and bone resorption in short and medium term trials, and they could be of particular interest in the prevention of osteoporosis in addition to calcium-rich waters.