Rebholz CM, et al. - In 2 independent studies of chronic kidney disease patients viz, the African American Study of Kidney Disease and Hypertension (AASK) comprising 689 patients and the Modification of Diet in Renal Disease (MDRD) with 356 patients, researchers investigated blood biomarkers of dietary acid load by using metabolomics. Net endogenous acid production (NEAP) based on 24-h urine urea nitrogen and potassium was estimated to determine dietary acid load. They identified 13 replicated metabolites related to dietary acid load; including 5 amino acids (S-methylmethionine, indolepropionylglycine, indolepropionate, N-methylproline, N-δ-acetylornithine), 2 cofactors and vitamins (threonate, oxalate), 1 lipid (chiro-inositol), and 5 xenobiotics (methyl glucopyranoside, stachydrine, catechol sulfate, hippurate, and tartronate). In both AASK and the MDRD study, lower NEAP was detected in relation to higher levels of all 13 replicated metabolites.