Carotenoids form an important part of the human diet, consumption of which has been associated with many health benefits. With the growing global burden of liver disease, increasing attention has been paid on the possible beneficial role that carotenoids may play in the liver. This review focuses on carotenoid actions in non-alcoholic fatty liver disease (NAFLD), and alcoholic liver disease (ALD). Indeed, many human studies have suggested an association between decreased circulating levels of carotenoids and increased incidence of NAFLD and ALD. The literature describing supplementation of individual carotenoids in rodent models of NAFLD and ALD is reviewed, with particular attention paid to β-carotene and lycopene, but also including β-cryptoxanthin, lutein, zeaxanthin, and astaxanthin. The effect of beta-carotene oxygenase 1 and 2 knock-out mice on hepatic lipid metabolism is also discussed. In general, there is evidence to suggest that carotenoids have beneficial effects in animal models of both NAFLD and ALD. Mechanistically, these benefits may occur via three possible modes of action: 1) improved hepatic antioxidative status broadly attributed to carotenoids in general, 2) the generation of vitamin A from β-carotene and β-cryptoxanthin, leading to improved hepatic retinoid signaling, and 3) the generation of apocarotenoid metabolites from β-carotene and lycopene, that may regulate hepatic signaling pathways. Gaps in our knowledge regarding carotenoid mechanisms of action in the liver are highlighted throughout, and the review ends by emphasizing the importance of dose effects, mode of delivery, and mechanism of action as important areas for further study. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.

类胡萝卜素是人类饮食的重要组成部分，食用它与许多健康益处有关。随着全球肝脏疾病负担的增加，人们越来越关注类胡萝卜素可能在肝脏中可能发挥的有益作用。这篇综述着重于非酒精性脂肪性肝病（NAFLD）和酒精性肝病（ALD）中的类胡萝卜素作用。确实，许多人体研究表明，类胡萝卜素的循环水平降低与NAFLD和ALD发生率增加之间存在关联。综述了描述在NAFLD和ALD啮齿动物模型中补充单个类胡萝卜素的文献，特别关注β-胡萝卜素和番茄红素，但也包括β-隐黄质，叶黄素，玉米黄质和虾青素。还讨论了β-胡萝卜素加氧酶1和2敲除小鼠对肝脂质代谢的影响。通常，有证据表明类胡萝卜素在NAFLD和ALD的动物模型中均具有有益的作用。从机械上讲，这些益处可能通过三种可能的作用方式产生：1）一般归因于类胡萝卜素的肝抗氧化状态改善； 2）β-胡萝卜素和β-隐黄质生成维生素A，从而改善了肝类维生素A信号传导；以及3）由β-胡萝卜素和番茄红素生成的类胡萝卜素代谢产物可能会调节肝信号通路。我们一直在强调关于肝脏中类胡萝卜素作用机制的知识空白，并且在审查过程中着重强调了剂量效应，分娩方式，和作用机制是有待进一步研究的重要领域。本文是由约翰内斯·冯·林提格（Johannes von Lintig）和洛雷丹娜·夸德罗（Loredana Quadro）编辑的《类胡萝卜素在细胞和分子生物学领域的最新进展》特刊的一部分。