Background: Dietary Na+ or Na+/K+ ratio has been reported to be associated with bone mineral density (BMD). However, this remains unclear, and only a few studies have been reported on the Korean population. Therefore, this study aimed to determine the association between dietary Na+, K+, and Na+/K+ ratios and BMD in middle-aged Korean women.

Methods: This study used data from the Korea National Health and Nutrition Examination Survey 2008–2011. A total of 3,690 women aged ＞50 years were included. Study participants were classified into quartiles (lowest quartile Q1–highest quartile Q4) according to dietary Na+, K+, and Na+/K+ ratio, and we examined the association of these parameters with BMD. Total femur and lumbar spine BMD were measured using dual-energy X-ray absorptiometry. Multiple linear regression analyses were performed using IBM SPSS ver. 19.0.

Results: The mean age was 62 years, and a significant negative trend in the β-coefficient regarding dietary Na+ was only observed in the total femur BMD. However, the total femur and lumbar spine BMD decreased from Q1 to Q4 regarding the dietary Na+/K+ ratio (P-value for trend: 0.044 for total femur BMD and 0.002 for lumbar spine BMD).

Conclusion: A significant negative trend in the β-coefficient for both total femur and lumbar spine BMD was observed regarding the Na+/K+ ratio. Therefore, based on the results of this study, a higher dietary Na+/K+ ratio may be associated with a lower BMD.