2-Hydroxyhippuric acid, also known as salicyluric acid, is used as a biomarker in metabolomics research, particularly for assessing exposure to salicylic acid or phenolic compounds from dietary sources such as fruits, coffee, and plants. It is a metabolite formed through glycine conjugation of salicylic acid and is primarily excreted in urine, aiding in the evaluation of health status, antioxidant intake, and metabolic processes. Additionally, it serves as an indicator in microbiome studies, as it is produced by gut microbiota during the breakdown of phenolic acids.