In the early 1930s, Banting and Best, the discoverers of insulin, found that choline could prevent the development of fatty liver disease (steatosis) in pancreatectomized dogs treated with insulin. Later work indicated that in rats and mice, diets deficient in labile methyl groups (choline, methionine, betaine, folate) produced fatty liver and that long-term administration of diets deficient in choline and methionine also caused hepatocellular carcinoma. These experiments not only linked steatosis and diabetes but also provided evidence, for the first time, of the importance of labile methyl group balance to maintain normal liver function. This conclusion is now amply supported by the observation of mice devoid of key enzymes of methionine and folate metabolism and in patients with severe deficiencies in these enzymes. Moreover, treatments with various methionine metabolites in experimental animal models of liver disease show hepatoprotective properties.

中文翻译：

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蛋氨酸代谢与肝脏疾病。

在1930年代初期，胰岛素的发现者Banting and Best发现胆碱可以预防用胰岛素治疗的胰腺切除犬的脂肪肝疾病（脂肪变性）的发展。后来的工作表明，在大鼠和小鼠中，缺乏甲基的饮食（胆碱，蛋氨酸，甜菜碱，叶酸）会产生脂肪肝，长期服用缺乏胆碱和蛋氨酸的饮食也会引起肝细胞癌。这些实验不仅将脂肪变性和糖尿病联系起来，而且首次提供了不稳定的甲基平衡对维持正常肝功能的重要性的证据。现在，通过观察缺乏蛋氨酸和叶酸代谢关键酶的小鼠以及这些酶严重缺乏的患者，这一结论得到了充分的支持。此外，