The Potential of Metabolomics as a Tool for Identifying Biomarkers Associated with Obesity and Its Complications: A Scoping Review.

Obesity and its related diseases, such as type 2 diabetes (T2DM), cardiovascular disease (CVD), and metabolic fatty liver disease (MAFLD), require new diagnostic markers for earlier detection and intervention. The aim of this study is to demonstrate the potential of metabolomics as a tool for identifying biomarkers associated with obesity and its comorbidities in every age group. The presented systematic review makes an important contribution to the understanding of the potential of metabolomics in identifying biomarkers of obesity and its complications, especially considering the influence of branched-chain amino acids (BCAAs), amino acids (AAs) and adipokines on the development of T2DM, MAFLD, and CVD. The unique element of this study is the combination of research results from the last decade in different age groups and a wide demographic range. The review was based on the PubMed and Science Direct databases, and the inclusion criterion was English-language original studies conducted in humans between 2014 and 2024 and focusing on the influence of BCAAs, AAs or adipokines on the above-mentioned obesity complications. Based on the PRISMA protocol, a total of 21 papers were qualified for the review and then assigned to a specific disease entity. The collected data reveal that elevated levels of BCAAs and some AAs strongly correlate with insulin resistance, leading to T2DM, MAFLD, and CVD and often preceding conventional clinical markers. Valine and tyrosine emerge as potential markers of MAFLD progression, while BCAAs are primarily associated with insulin resistance in various demographic groups. Adipokines, although less studied, offer hope for elucidating the metabolic consequences of obesity. The review showed that in the case of CVDs, there is still a lack of studies in children and adolescents, who are increasingly affected by these diseases. Moreover, despite the knowledge that adipokines play an important role in the pathogenesis of obesity, there are no precise findings regarding the correlation between individual adipokines and T2DM, MAFLD, or CVD. In order to be able to introduce metabolites into the basic diagnostics of obesity-related diseases, it is necessary to develop panels of biochemical tests that will combine them with classical markers of selected diseases.