Effects of α- and β-Carotene on Liver Diseases Improvement: A Systematic Review

Objectives: Chronic liver disease (CLD) has become a major disease that threatens human health. Oxidative stress (OS) is a major contributor to the deterioration of CLD. α- and β-carotene, naturally occurring micronutrients with biological activities such as anti-oxidant, anti-inflammatory and anti-cancer, have been used to defend against or treat CLD. This systematic review aims to explore the role of α- and β-carotene in the prevention and treatment of CLD. Methods: A comprehensive literature search was undertaken on PubMed, EMBASE, Web of Science and CNKI databases from 1993 to 2021, with a deadline of January 2023, and 16 studies were ultimately included in this review. Result: β-carotene supplementation significantly reduced liver fibrosis (SMD = 39.78, 95% CI [−55.55, −24.01]), while gender and obesity status showed no statistical difference. Dietary α‑carotene intake was not associated with a reduced risk of non-alcoholic fatty liver disease (NAFLD) (SMD = 1.09, 95% CI [0.82, 1.36]). However, the serum carotene measurement group with carotenoid supplementation (MD = −5.79; 95% CI [−109.58, 98.00]) was a trend toward improvement of liver disease. Conclusions: Dietary intake of β-carotene tends to reduce the risk of liver disease, while dietary α-carotene intake was not associated with a reduced risk of liver cancer and NAFLD in obese populations, which inspired us to develop fresh concepts for modifying meals for various populations.