Relationship of vitamin D intake, serum 25(OH) D, and solar ultraviolet-B radiation with the risk of gastric cancer: A meta-analysis

The purpose of this meta-analysis was to investigate whether vitamin D intake, serum 25(OH) D, and solar ultraviolet-B (UVB) radiation have an effect on the incidence of gastric cancer. Keyword searches of online databases were performed from January 2000 to October 2020. A comprehensive analysis was conducted on the relationship of vitamin D intake, serum 25(OH) D level, and UVB radiation with the risk of gastric cancer. A total of 11 articles were included and analyzed. When the highest and lowest intake levels of vitamin D were compared, no significant association was found between vitamin D intake and gastric cancer incidence [effect size (ES): 1, 95% confidence interval (CI): 0.86-1.16, P = 0.983]. The ES of serum 25(OH) D level and gastric cancer incidence was 0.93 (95% CI: 0.77-1.11, P = 0.4), suggesting no relationship between 25(OH) D level and gastric cancer risk. High UVB radiation was associated with lower gastric cancer incidence (ES: 0.86, 95% CI: 0.84-0.89, P = 0) compared with low UVB radiation. Vitamin D intake and serum 25(OH) D level had no relationship with the risk of gastric cancer. However, an inverse association was found between solar UVB radiation and gastric cancer incidence.