Adding salt to foods, genetic susceptibility, and risk of incident osteoporosis

OBJECTIVES: To investigate the association between the frequency of adding salt to foods and incident osteoporosis and assess effect modification by genetic susceptibility. DESIGN: Prospective cohort study. SETTING: UK Biobank, United Kingdom. PARTICIPANTS: 491,428 participants free of osteoporosis at baseline. MEASUREMENTS: Frequency of adding salt to foods (excluding salt used in cooking) was assessed by questionnaire and categorized as never/rarely, sometimes, usually, or always. Multivariable Cox models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for incident osteoporosis and secondary cardiovascular outcomes. RESULTS: During a median follow-up of 14.7 years, 15,953 osteoporosis cases were documented. Compared with the never/rarely group, fully adjusted HRs were 1.09 (95% CI 1.04-1.15) for usually and 1.32 (95% CI 1.24-1.41) for always (P for trend <0.001). The association was stronger in men, White participants, and those with higher BMI. In joint analyses, participants with high genetic risk who always added salt had the highest risk (HR 2.68, 95% CI 2.41-2.98). In the same cohort, always adding salt was also associated with higher cardiovascular mortality (HR 1.18, 95% CI 1.14-1.23) and cardiovascular events (HR 1.21, 95% CI 1.17-1.26). CONCLUSION: A higher frequency of adding salt to foods was associated with a higher risk of incident osteoporosis. Together with the cardiovascular associations observed in this cohort, these findings suggest that adding salt to foods may be a modifiable behavior relevant to multiple age-related diseases.