Acid-base homeostasis is essential for human health and a variety of physiological conditions. Pathophysiological changes can result in acid-base derangements, which can be accompanied by acute and long-term metabolic disorders. Moreover, even a narrow change of blood pH still within the physiological change, e.g., a diet-induced shift towards a more acidic status, has been reported to already cause adverse health consequences. Against this background, we aimed to, by using non-invasive urinary biomarkers, examine acid-base-related physiological and epidemiological relationships of body fatness with 24-h urine pH, the potential mediatory roles of inflammatory biomarkers in the high body fat¿low urine pH relation, and the association between 24-h urinary glucocorticoid excretion and renal citrate output, as well as the prospective relationships of protein intake and dietary acid load during childhood and adolescence with adult height. All study participants were selected and data came from the DOrtmund Nutritional and Antropometric Longitudinally Designed (DONALD) Study, which includes regular examinations on dietary intake, metabolism, and growth in healthy children and adolescents until their adulthood without particular pre-specified endpoints.