Dear Editor,

We read with interest the article “Associations among vitamin D, tobacco smoke, and hypertension: A cross-sectional study of the NHANES 2001–2016” by Wu et al. [1], in which the authors used NHANES database, and found that the increased risk of hypertension could be partly attributed to low vitamin D levels induced by tobacco smoke exposure. We appreciate the efforts of the authors for to shed light on this valuable and instructive topic for health policy. However, there was one question that we would like to communicate.

Data in this study included NHANES 2001–2016. However, we found that data for 25(OH)D from NHANES 2007–2010 can not be downloaded (https://wwwn.cdc.gov/Nchs/Nhanes/Search/DataPage.aspx?Component=Laboratory&CycleBeginYear=2009). Therefore, we would like to know how the authors got these data.

We once again thank the authors for their contributions and hope that there will be more and better research studies in this area.