Research Progress in the Effects of Sulfur-Containing Amino Acids on Metabolic Health and a Review of the Methods for Their Detection

Sulfur-containing amino acids (SAA), primarily including methionine, cysteine and cystine, are abundant in foods and play important roles in maintaining metabolic health. This article begins with a summary of the effects of varying levels of SAA intake on metabolic health. It discusses the benefits associated with moderate SAA restriction, such as lipid-and glucose-lowering effects, mitigation of oxidative stress, and extension of lifespan. It also covers the detrimental effects of excessive SAA restriction, such as growth retardation, increased oxidative stress, and reduced bone mass. Additionally, it explores the benefits of moderate additional SAA intake, such as promoting protein synthesis, improving liver glucose and lipid metabolism, and regulating redox homeostasis. It highlights the detrimental effects of excessive additional SAA intake, such as glucose and lipid metabolic disorders, increased oxidative stress, and an increased risk of cardiovascular diseases. Subsequently, this article reviews the sample pre-treatments (acid hydrolysis, oxidative hydrolysis, and dithiothreitol oxidative hydrolysis) and analytical methods (indirect analysis after derivatization and spectrophotometry) currently used to detect the SAA content in foods, with a discussion about their advantages and disadvantages. Finally, the methods for achieving SAA precision nutrition and their applications are examined. This review is expected to provide theoretical references for SAA detection in foods and the improvement of metabolic health through precision regulation of dietary SAA intake.