“…The protocol below describes the procedure for polar metabolomics in human muscle biopsies ( Janssens et al., 2022 ), but the same protocol has been successfully applied for human ( Remie et al., 2021 ; Connell et al., 2021 ; Remie et al., 2020 ), mouse ( van der Stelt et al., 2021 ; Zapata-Pérez et al., 2021 ) or rat tissues (brown adipose tissue, white adipose tissue, heart, liver, kidney, brain, placenta, arterial plaque), cultured cells (primary skin fibroblasts, Human Embryonic Kidney (HEK) cells, bronchial epithelial cells, cumulus cells, oocytes, organoids), blood samples ( Zapata-Pérez et al., 2021 ) (serum, plasma, erythrocytes, platelets, peripheral blood mononuclear cells, whole blood, macrophages), other bodily fluids (saliva, sweat, urine, fecal water, bile, cerebrospinal fluid), model organisms ( Molenaars et al., 2021 ; Liu et al., 2020 ; Gao et al., 2018 ; Molenaars et al., 2020 ) (yeast, fruit flies, zebrafish and C. elegans) and culture medium. Additional details on these matrices can be found in Table S1 Sample Matrix Overview.…”