Anthropometrics Provide a Better Estimate of Urinary Organic Acid Anion Excretion than a Dietary Mineral Intake-Based Estimate in Children, Adolescents, and Young Adults

• Published in: The Journal of nutrition Vol. 136; no. 5; pp. 1203 - 1208
• Main Authors: Berkemeyer, Shoma, Remer, Thomas
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Nutrition 01.05.2006; American Society for Nutritional Sciences
• Subjects: Adolescent; adolescent nutrition; adolescents; Adult; Anions; anthropometric measurements; Biological and medical sciences; Body Height; Body Mass Index; Body Weight; Carboxylic Acids; Carboxylic Acids - urine; Child; child growth; child nutrition; children; Diet; dietary fat; dietary minerals; dietary protein; Energy Intake; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; gender differences; homeostasis; Humans; Male; Minerals; nutrient intake; organic acids and salts; surface area; urination; urine; Vertebrates: anatomy and physiology, studies on body, several organs or systems; young adults; Human; Urine; Biological fluid; 24-hour urine; Excretion; Healthy subject; Nutrition; healthy subjects; dietary potential renal acid load; Minerals; Inorganic element; Organic acids; Kidney; Feeding; Anions; Urinary system; Food intake; Adolescent; Young adult; acid-base; organic acid estimates; Child
• ISSN: 0022-3166
• DOI: 10.1093/jn/136.5.1203

The role of elevated net endogenous acid production (NEAP) in the causation of osteoporosis, muscle wasting, and kidney stones is currently under discussion. The aim of this study was to examine whether urinary organic acid anion excretion, a major component of NEAP, is predicted primarily by anthropometric- (OA[subscript anthro]) or diet- (OA[subscript diet]) based estimates. Dietary intakes, anthropometric data, and 24-h urinary excretion rates of organic acids (24h-OA[subscript urine]) were determined cross sectionally in healthy children (6-7 y; n = 217), adolescents (13-14 y; n = 91), and young adults (18-22 y; n = 82). OA[subscript anthro] was computed from body surface area and OA[subscript diet] calculated using a published algorithm based on dietary intakes of mineral anions and cations. There was a significant increase (P < 0.0001) in 24h-OA[subscript urine] across the age groups that was no longer discernible after correction for body surface area. In almost all sex-stratified subsamples, OA[subscript anthro] had a higher correlation with 24h-OA[subscript urine] than OA[subscript diet]. Multiple regression analyses, using energy-corrected diet variables, revealed that OA[subscript anthro] was consistently the primary predictor of 24h-OA[subscript urine] (R² varying from 0.15 to 0.39) and dietary fat and protein were sporadic predictors. In accordance with the observed age independency of 24h-OA[subscript urine] after body surface area correction, our findings indicate that OA[subscript anthro] is a better estimate of 24h-OA[subscript urine] in healthy children, adolescents, and young adults than OA[subscript diet]. This further confirms that the (principally diet-dependent) NEAP comprises a component, i.e., organic acid anions, that is reasonably predictable by anthropometrics. Consequently, the other component, i.e., the potential renal acid load, appears to be the primary parameter that characterizes the diet-induced acid load.