Global research on vitamin D and coronavirus disease 2019: A bibliometric and visualized study.

It was concluded that an increasing trend in the number of publications on vitamin D and COVID-19 has been observed. Significantly, the majority of the research has been conducted in developed countries. Most importantly, over the time, the direction of research has been changed and the recent trend topics are vitamin D deficiency, risk and infection, and vitamin D supplementation based on KeyWords Plus. The use of vitamin D supplement is one of the promising therapeutic options for COVID-19 treatment. Therefore, the current study not only highlight the global research trends but also provide standard bibliographic information for future studies.