Sodium (Na) intake is the major factor linking blood pressure and osteoporosis, say scientists from Hong Kong.
“The link between hypertension and osteoporosis has not received much attention, in terms of common underlying pathogenetic mechanisms,” note Jean Woo (The Chinese University of Hong Kong, Shatin) and co-researchers.
However, “both hypertension and osteoporosis have common underlying nutritional etiology, with regards to dietary cations intake.”
To investigate, Woo and team measured blood pressure, bone mineral density (BMD), and the dietary intake of cations in 1098 volunteers (74% women) aged 65 years and over.
They collected a fasting urine sample to analyze levels of Na, potassium (K) and creatinine (Cr). The ratios of Na to Cr and K to Cr were used as indicators of dietary sodium and potassium intake.
Using logistic regression, the researchers found that total hip BMD was inversely associated with age, being female, and urinary Na/Cr, and positively associated with body mass index (BMI), urine K/Cr and dietary calcium intake.
No association was observed between hip BMD and systolic or diastolic blood pressure.
Lumbar spine BMD was inversely associated with being female and urinary Na/Cr, and positively associated with BMI, dietary calcium intake, and systolic blood pressure.
“This finding supports the pathway of increased obligatory calcium excretion with increased sodium excretion as a result of increased dietary sodium intake, as the common underlying pathogenetic mechanism for both hypertension and osteoporosis,” conclude Woo et al.
They add that their results “lend further emphasis to the health benefits of salt reduction in our population both in terms of hypertension and osteoporosis.”
The study findings are published in the Journal of Human Hypertension.