Sodium and Bone Health: Impact of Moderately High and Low Salt Intakes on Calcium Metabolism in Postmenopausal Women

• Published in: Journal of bone and mineral research Vol. 23; no. 9; pp. 1477 - 1485
• Main Authors: Teucher, Birgit, Dainty, Jack R, Spinks, Caroline A, Majsak‐Newman, Gosia, Berry, David J, Hoogewerff, Jurian A, Foxall, Robert J, Jakobsen, Jette, Cashman, Kevin D, Flynn, Albert, Fairweather‐Tait, Susan J
• Format: Journal Article
• Language: English
• Published: Washington, DC John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR) 01-09-2008; American Society for Bone and Mineral Research
• Subjects: Aged; Biological and medical sciences; Biomarkers - metabolism; Bone and Bones - drug effects; Bone and Bones - metabolism; bone biomarkers; Bone Resorption - metabolism; Bone Resorption - urine; Calcium - metabolism; Calcium - urine; calcium absorption; Calcium, Dietary - pharmacology; Diet; Diet, Sodium-Restricted; Feeding Behavior - drug effects; Female; Fundamental and applied biological sciences. Psychology; Health; Hormones - metabolism; Humans; Intestinal Absorption - drug effects; Kinetics; Middle Aged; Models, Biological; Osteogenesis - drug effects; Phosphorus - urine; postmenopausal women; Postmenopause - drug effects; Postmenopause - urine; Potassium - urine; salt; Skeleton and joints; Sodium - metabolism; Sodium - urine; Sodium Chloride, Dietary - pharmacology; Vertebrates: osteoarticular system, musculoskeletal system; salt; Calcium; postmenopausal women; Health; Biological marker; calcium absorption; Metabolism; Inorganic element; calcium metabolism; Osteoarticular system; Vertebrata; Absorption; Mammalia; Sodium; bone biomarkers; Postmenopause; Female; Bone
• ISSN: 0884-0431; 1523-4681
• DOI: 10.1359/jbmr.080408

High salt intake is a well‐recognized risk factor for osteoporosis because it induces calciuria, but the effects of salt on calcium metabolism and the potential impact on bone health in postmenopausal women have not been fully characterized. This study investigated adaptive mechanisms in response to changes in salt and calcium intake in postmenopausal women. Eleven women completed a randomized cross‐over trial consisting of four successive 5‐wk periods of controlled dietary intervention, each separated by a minimum 4‐wk washout. Moderately low and high calcium (518 versus 1284 mg) and salt (3.9 versus 11.2 g) diets, reflecting lower and upper intakes in postmenopausal women consuming a Western‐style diet, were provided. Stable isotope labeling techniques were used to measure calcium absorption and excretion, compartmental modeling was undertaken to estimate bone calcium balance, and biomarkers of bone formation and resorption were measured in blood and urine. Moderately high salt intake (11.2 g/d) elicited a significant increase in urinary calcium excretion (p = 0.0008) and significantly affected bone calcium balance with the high calcium diet (p = 0.024). Efficiency of calcium absorption was higher after a period of moderately low calcium intake (p < 0.05) but was unaffected by salt intake. Salt was responsible for a significant change in bone calcium balance, from positive to negative, when consumed as part of a high calcium diet, but with a low calcium intake, the bone calcium balance was negative on both high and low salt diets.