Study design and population

The National Health and Nutrition Examination Survey (NHANES), a research program to assess the health and nutrition of adults and children in the United States, examining a nationally representative sample of approximately 5,000 people each year. In this study, we used NHANES data for 2013–2014 and 2017–2018. Of 19429 subjects, 12728 subjects with available blood manganese data were selected. After that, 2996 subjects lacking available Dual Energy X-ray Absorptiometry (DEXA) data were excluded. Finally, A total of 9732 subjects with available DEXA data on total body (n = 3682), femur (n = 3752), and spine (n = 2298) were enrolled. The Ethics Review Committee of the National Center for Health Statistics approved all NHANES protocols and obtained written informed consents from all participants [16]. The flow chart (Fig 1) also shows the selection process. All methods were performed in accordance with the relevant guidelines and regulations.

NHANES, National Health and Nutrition Examination Survey; DEXA, Dual Energy X-ray Absorptiometry.