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Abstract

In a recent study1.Escribano J. Luque V. Ferre N. et al.Increased protein intake augments kidney volume and function in healthy infants.Kidney Int. 2011; 79: 783-790Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar we demonstrated that a higher protein intake in healthy infants during the first months of life was associated with an increase in kidney size. Schreuder2.Schreuder M.F. Perinatal programming of the kidney: is bigger always better?.Kidney Int. 2011; 79: 783-790Abstract Full Text Full Text PDF PubMed Scopus (49) Google Scholar has questioned whether this renal overgrowth may be beneficial or harmful in the long term. An increase in protein intake may lead to renal functional overload caused by nitrogenous products derived from protein metabolism, which can cause a compensatory kidney overgrowth. Because the intervention of this trial occurred after the nephrogenesis period, it is logical to think that overgrowth must have been caused by a hypertrophy of the nephron structures rather than an increase in the glomeruli number. We have also tested how high intake of protein causes increased body mass for up to 2 years of life.3.Koletzko B. von Kries R. Closa R. et al.Lower protein in infant formula is associated with lower weight up to age 2 y: a randomized clinical trial.Am J Clin Nutr. 2009; 89: 1-10Crossref PubMed Scopus (507) Google Scholar This increase in body mass may lead to a secondary increase of renal workload. If this is not accompanied by an increase in the excretory capacity (not increasing the nephron number), it will create an imbalance that can promote the functional overload. This single nephron hyperfiltration would be at the risk of progressive renal disease.4.Bagby S.P. Maternal nutrition, low nephron number, and hypertension in later life: pathways of nutritional programming.J Nutr. 2007; 137: 1066-1072PubMed Scopus (129) Google Scholar If protein intake in the early stages of development is reduced, we would be able to benefit metabolic programming, reducing later obesity risk. This measure may lead to smaller kidneys, but with similar functional reserve, and not cause an overload that could be harmful to later health. In this case, smaller body mass and smaller kidneys could be better. The follow-up studies attempted in this cohort are important to explore the potential long-term effects. This work has been carried out with partial financial support from the Commission of the European Communities, specific RTD Programme ‘Quality of Life and Management of Living Resources’, within the 5th Framework Programme, research grants no. QLRT-2001-00389 and QLK1-CT-2002-30582, and the 6th Framework Programme, contract no. 007036. This manuscript does not necessarily reflect the views of the Commission and in no way anticipates the future policy in this area. CHOP Study Group: Ferre N, Zaragoza-Jordana M, Mendez G (Pediatrics Unit, Universitat Rovira i Virgili, Reus, Spain), Grote V, Beyer J, Demmelmair H, Fritsch M, Haile G, Handel U, Hannibal I, Kreichauf S, Pawellek I, Schiess S, Verwied-Jorky S, von Kries R, Weber M (Division of Pediatric Epidemiology, Institute of Social Pediatrics and Adolescent Medicine and Division of Nutritional Medicine and Metabolism, Dr von Hauner Children's Hospital, Ludwig Maximilians University of Munich), Gruszfeld D, Socha P, Dobrzanska A, Janas R, Kowalik A, Pietraszek E, Stolarczyk A, Socha J (Children's Memorial Health Institute, Warsaw, Poland), Carlier C, Dain E, Van Hees JN, Goyens P, Hoyos J, Langhendries J-P, Martin F, Poncelet P, Xhonneux A (ULB Bruxelles and CHC St Vincent Liege), Perrin E (Danone Research Centre for Specialized Nutrition, Schiphol, The Netherlands), Agostoni C, Giovannini M, Re Dionigi A, Riva E, Scaglioni S, Vecchi F, Verducci E (University of Milan).