A systematic review and meta-analysis of the association between vitamin A intake, serum vitamin A, and risk of liver cancer:

Background:Previous evidence supports that vitamin A decreases the risk of several types of cancer. However, the association between vitamin A and liver cancer is inconclusive.Aim:This systematic review and meta-analysis summarizes the existing literature, discussing the association between vitamin A intake, serum vitamin A, and liver cancer in adult populations.Methods:A systematic literature review was performed by searching the EMBASE, PubMed, Scopus and International Pharmaceutical Abstract databases using terms related to vitamin A (e.g. retinol, α-carotene, β-carotene, and β-cryptoxanthin) and hepatic cancer without applying any time restriction. A meta-analysis was performed using random effect models.Results:The meta-analysis of five studies showed no association between serum retinol and liver cancer (pooled risk ratio = 1.90 (0.40–9.02); n = 5 studies, I2 = 92%). In addition, the systematic review of studies from 1955 to July 2017 found studies that indicated no association between the intake an...