Low vitamin A levels are associated with liver-related mortality: a nationally representative cohort study

Vitamin A, a fat-soluble vitamin that includes retinol and carotenoids, is implicated in liver fibrosis, whereas its deficiency has been associated with various liver diseases and higher overall mortality. This study aims to determine the relationship between levels of vitamin A species and liver fibrosis, as well as liver-related mortality in the population of the US. METHODS: A total of 12,299 participants from the National Health and Nutrition Examination Survey III (NHANES III) were analyzed to provide nationally representative estimates of the relationship between the levels of vitamin A species and liver fibrosis measured by Fibrosis-4 (FIB-4) index and liver-related mortality. RESULTS: A low blood level of retinol, but not other retinoid derivatives, was associated with significant liver fibrosis after adjustment for demographics, anthropometric measurements, medical history, retinol, and carotene intakes. Compared with vitamin D and E, retinol deficiency demonstrated much stronger associations with a high FIB-4 score. Individuals with known risks of chronic liver disease (CLD) and the lowest pentile of retinol levels had ORs of 3.12 (95% CI, 1.64–5.91) for possible fibrosis and 19.7 (95% CI, 5.71–67.7) for likely fibrosis, and an HR of 7.76 (95% CI, 1.19–50.5) for liver-related mortality compared with those in the highest retinol-level pentile. These relationships were more pronounced among individuals with known risks of chronic liver disease than without. CONCLUSIONS: A low circulating retinol level is associated with liver fibrosis and liver-related mortality in chronic liver disease. This relationship is potentially driven by a mechanistic link rather than the malabsorption of fat-soluble vitamins and may be leveraged for disease prognostication and have therapeutic implications.