Dietary intake, blood pressure and osteoporosis.

Both hypertension and osteoporosis have common underlying nutritional aetiology, with regards to dietary cations intake. We tested the hypothesis that sodium intake reflected in urinary Na/Cr and blood pressure would be negatively associated with bone mineral density (BMD), whereas other cations may have opposite associations. Subjects were part of a study of bone health in 4000 men and women aged 65 years and over. A total of 1098 subjects who were not on antihypertensive drugs or calcium supplements and who provided urine samples were available for analysis. Logistic regression was used to examine associations between total hip and lumbar spine BMD, age, gender, body mass index (BMI), urinary Na/Cr, K/Cr, calcium and magnesium intake, systolic blood pressure and diastolic blood pressure. Total hip BMD was inversely associated with age, being female and urinary Na/Cr, and positively associated with BMI, urine K/Cr and dietary calcium intake. Lumbar spine BMD was inversely associated with being female and urinary Na/Cr, and positively associated with BMI, dietary calcium intake and SBP. We conclude that sodium intake, reflected by urinary Na/Cr, is the major factor linking blood pressure and osteoporosis as shown by the inverse relationship with BMD. The findings lend further emphasis to the health benefits of salt reduction in our population both in terms of hypertension and osteoporosis.