Review of risk factors for osteoporosis with particular reference to a possible aetiological role of dietary salt

• Published in: Food and Chemical Toxicology 2000-02, Vol.38 (2), p.237-253
• Main Authors: Cohen, A.J, Roe, F.J.C
• Format: Article
• Language: English
• Subjects: Adult; Aged; Animals; Biological and medical sciences; Biomarkers; bone health; bone resorption; Bone Resorption - physiopathology; caffeine; Calcium - urine; calcium homeostasis; Diseases of the osteoarticular system; Female; Humans; Hypertension; Male; Medical sciences; Middle Aged; osteoporosis; Osteoporosis - etiology; Osteoporosis. Osteomalacia. Paget disease; Postmenopause; Rats; Risk Assessment; salt; sodium chloride; Sodium Chloride, Dietary - adverse effects
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/S0278-6915(99)00145-3

Laboratory animal, clinical and epidemiological studies in the published literature have been reviewed in order to establish whether excessive salt intake is an important risk factor for the development of osteoporosis and whether an intervention strategy based on salt restriction would be beneficial in the prevention of osteoporosis. Genetic factors appear to be far more important than the combination of nutritional, hormonal, environmental and lifestyle factors in the pathogenesis of osteoporosis. The most important single non-genetic factor is oestrogen deficiency in postmenopausal women. Preventive measures should be aimed at maximizing peak bone mass at skeletal maturity and retarding bone loss thereafter. Apart from postmenopausal oestrogen deficiency, various factors have been incriminated as risk factors for osteoporosis, and these include age at menarche, age at and years since menopause, insufficient physical exercise, alcohol, smoking, low calcium intake, low or high protein intake and high intake of phosphorus, sodium or caffeine. Many of the risk factors are considered to be weak, although when combined they could impact significantly on bone health. Increased intakes of various nutritional factors (potassium, magnesium, zinc, vitamin C), fibre and alkaline-producing fruit and vegetables favour adult bone health. Calcium homeostasis is normally well regulated such that increased calcium loss via the urine leads to increased calcium absorption from the gut. However, the duration of this adaptive process may be greater than that of many of the studies demonstrating that increased salt intake leads to both increased sodium and calcium in the urine. In any case, higher urinary calcium output appears to be seen only in a minority of humans in response to increased salt intake. As numerous factors—genetic, nutritional, hormonal and lifestyle—are involved in the maintenance of calcium homeostasis, it is difficult to devise human studies which adequately take into account all the important factors. Another difficulty is that many past studies have relied on imprecise methods for the measurement of bone resorption. Nor have studies based on the use of the laboratory rat produced clear answers to the problem because the rat, as a species, is uniquely deficient in its ability to handle the relevant minerals. Limited studies to date indicate that increased sodium intake neither exerts a consistent effect on various biomarkers of bone health nor leads to i