Association between plasma total homocysteine level within normal range and bone mineral density in adults

BACKGROUND: Growing evidence indicates that homocysteine is a noteworthy marker for general health status. However, research regarding plasma total homocysteine (tHcy) levels and bone mineral density (BMD) is sparse and controversial. Hence, we aimed to investigate the association between plasma tHcy level within normal range and lumbar BMD in adults. METHODS: In this cross-sectional study, using the National Health and Nutrition Examination Survey database, data on 10748 adults aged between 30 and 85 years were analyzed. The weighted multiple logistic regression analyses were conducted to evaluate the association between plasma tHcy level and lumbar BMD. The fitted smoothing curves were performed to explore potential non-linear relationships. When non-linearity was detected, we further calculated the inflection point using a recursive algorithm and constructed a weighted two-piecewise linear regression model. RESULTS: After adjusting for all the covariates, the association between plasma tHcy and lumbar BMD was different in various age groups (adults aged 30–49 years: β = −0.0004, 95% CI −0.0025, 0.0018; adults aged 50–69 years: β = 0.0001, 95% CI −0.0025, 0.0026; adults aged 70–85 years: β = 0.0050, 95% CI 0.0008, 0.0092). In the subgroup analysis stratified by gender, this association also differed based on gender. There was a negative trend in females (aged 30–49 years: β = −0.0022, 95% CI −0.0054, 0.0011; aged 50–69 years: β = −0.0028, 95% CI −0.0062, 0.0007), and a positive trend in males (aged 30–49 years: β = 0.0018, 95% CI −0.0012, 0.0048; aged 50–69 years: β = 0.0027, 95% CI −0.0009, 0.0063) in both 30–49 years group and 50–69 years group. In the 70–85 years group, this association was significantly positive in males (β = 0.0136, 95% CI 0.0068, 0.0204), but was not significantly different in females (β = 0.0007, 95% CI −0.0046, 0.0060). CONCLUSION: The correlation between plasma tHcy level within the normal range and lumbar BMD differs by age and gender.