Medicinal herbs and many food ingredients possess favorable biological properties that contribute to their therapeutic activities. One such natural product is betaine, a stable, nontoxic natural substance that is present in animals, plants, and microorganisms. Betaine is also endogenously synthesized through the metabolism of choline or exogenously consumed through dietary intake. Betaine mainly functions as (i) an osmolyte and (ii) a methyl-group donor. This review describes the major physiological effects of betaine in whole-body health and its ability to protect against both liver- as well as non-liver-related diseases and conditions. Betaine’s role in preventing/attenuating both alcohol-induced and metabolic-associated liver diseases has been well studied and is extensively reviewed here. Several studies show that betaine protects against the development of alcohol-induced hepatic steatosis, apoptosis, and accumulation of damaged proteins. Additionally, it can significantly prevent/attenuate progressive liver injury by preserving gut integrity and adipose function. The protective effects are primarily associated with the regulation of methionine metabolism through removing homocysteine and maintaining cellular SAM:SAH ratios. Similarly, betaine prevents metabolic-associated fatty liver disease and its progression. In addition, betaine has a neuroprotective role, preserves myocardial function, and prevents pancreatic steatosis. Betaine also attenuates oxidant stress, endoplasmic reticulum stress, inflammation, and cancer development. To conclude, betaine exerts significant therapeutic and biological effects that are potentially beneficial for alleviating a diverse number of human diseases and conditions.

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甜菜碱的有益作用：综合回顾

草药和许多食品成分具有有助于其治疗活动的有利生物学特性。一种这样的天然产物是甜菜碱，它是一种稳定、无毒的天然物质，存在于动物、植物和微生物中。甜菜碱也可通过胆碱的代谢内源性合成，或通过饮食摄入外源性消耗。甜菜碱主要用作 (i) 渗透剂和 (ii) 甲基供体。这篇综述描述了甜菜碱对全身健康的主要生理作用及其预防肝脏和非肝脏相关疾病和病症的能力。甜菜碱在预防/减轻酒精引起的和代谢相关的肝病方面的作用已得到充分研究，并在此处进行了广泛综述。几项研究表明，甜菜碱可防止酒精引起的肝脂肪变性、细胞凋亡和受损蛋白质积累的发展。此外，它可以通过保持肠道完整性和脂肪功能显着预防/减轻进行性肝损伤。保护作用主要与通过去除同型半胱氨酸和维持细胞 SAM:SAH 比率来调节甲硫氨酸代谢有关。同样，甜菜碱可预防与代谢相关的脂肪肝疾病及其进展。此外，甜菜碱具有神经保护作用，保护心肌功能，防止胰腺脂肪变性。甜菜碱还可以减轻氧化应激、内质网应激、炎症和癌症的发展。总而言之，