Association between dietary selenium intake and bone mineral density in the US general population.

Background: Osteoporosis, characterized by reduced bone mineral density (BMD) increases the risk of all-cause mortality. Assessments of whether dietary selenium intake is related to bone health are scarce, with few relevant studies limited by a small sample size. The aim of the present study was to investigate the association between dietary selenium intake and BMD levels in the National Health and Nutrition Examination Survey (NHANES) database. Methods: We extracted and aggregated data from 4 cycles of the NHANES [2005-2010, 2013-2014]. Dietary selenium intake was obtained from 24-hour dietary recall interviews. BMD measurement, including the femur, femur neck, trochanter and intertrochanter of the femur, and lumbar spine, was performed using dual-energy X-ray absorptiometry. The multivariable linear regression model for the association between dietary selenium intake and BMD and the generalized additive model (GAM) for the dose-response relationship were used. Results: A total of 21,939 participants were included. The mean age was 40.68±22.42 years, and 51.28% were male. In the multivariable adjustment model, participants with the highest quintiles of dietary selenium intake (Q5) were associated with increased BMD levels in the total femur (β=0.014, 95% CI: 0.008-0.020, P<0.001), femur neck (β=0.010, 95% CI: 0.004-0.016, P=0.001), trochanter (β=0.011, 95% CI: 0.005-0.017, P<0.001), intertrochanter (β=0.017, 95% CI: 0.010-0.025, P<0.001), and lumbar spine (β=0.013, 95% CI: 0.005-0.020, P<0.001) compared with those in quintile 1 (Q1). The dose-response relationship showed an inverted U-shape relationship between dietary selenium intake and BMD levels (P for nonlinearity <0.05). Participants tended to have increased levels of BMD as the dietary selenium intake increased when dietary selenium was below the turning point, and then a negative relationship was observed when dietary intake was higher than the turning point. Conclusions: Our study indicated that dietary selenium intake exhibited an inverted U-shape trend in relation to BMD levels, which demonstrates the need for selenium status in the body to be considered when discussing the role of dietary selenium intake in BMD. Future studies are needed to confirm these findings and explore the underlying biological mechanism.