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Title: Growth and clinical variables in nitrogen-restricted piglets fed an adjusted essential amino acid mix: Effects using free amino acid-based diets

Author
item LYKKE, MIKKEL - University Of Copenhagen
item SANGILD, PER - University Of Copenhagen
item VAN GOUDOEVER, JOHANNES - Vu University Medical Center
item VAN HARSKAMP, DEWI - Vu University Medical Center
item SCHIERBEEK, HENK - Vu University Medical Center
item KOLETZKO, BERTHOLD - Ludwig-Maximilians University
item VAN DER BEEK, ELINE - Utrecht University
item ABRAHAMSE-BERKEVELD, MARIEKE - Utrecht University
item VAN DE HEIJNING, BERT J.M. - Utrecht University
item STOLL, BARBARA - Children'S Nutrition Research Center (CNRC)
item Burrin, Douglas - Doug
item THYMANN, THOMAS - University Of Copenhagen

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2018
Publication Date: 7/1/2018
Citation: Lykke, M., Sangild, P.T., Van Goudoever, J.B., Van Harskamp, D., Schierbeek, H., Koletzko, B., Van Der Beek, E.M., Abrahamse-Berkeveld, M., Van De Heijning, B., Stoll, B., Burrin, D.G., Thymann, T. 2018. Growth and clinical variables in nitrogen-restricted piglets fed an adjusted essential amino acid mix: Effects using free amino acid-based diets. Journal of Nutrition. 148(7):1109-1117. http://doi.org/10.1093/jn/nxy072
DOI: https://doi.org/10.1093/jn/nxy072

Interpretive Summary: The protein and amino acid requirements for human infants is based on their concentration in human milk. However, most infant formulas contain much higher protein levels than human milk. Recent studies have implicated that the higher protein intake from infant formula may result in accelerated weight gain in infancy that leads to increased risk for metabolic disease later in life, such as obesity. More recent studies using stable isotopes have suggested that the amino acid requirements for human infants may need to be revised. In the current study, we used neonatal pigs to test whether a purified, amino acid-based formula with lower overall content (20% lower) but more optimal composition of amino acids would support growth and organ development in the first two weeks of life. The results showed that pigs fed a formula with 20% lower protein content, with both a standard and optimized amino acid composition, had similar growth rates and no adverse effects compared to pigs fed a normal protein diet. We also found that pigs fed the lower protein, optimized amino acid content diet metabolized less leucine than those fed the normal protein diet suggesting that it was more efficiently used for growth. This study supports that idea that reducing the protein content and optimizing the amino acid composition of infant formula may be safe and support normal growth in infants.

Technical Abstract: Excess protein intake in early life has been linked to obesity and metabolic syndrome in later life. Yet, protein, and in particular the essential amino acids (EAA), need to be present in adequate quantity to support growth. Using a piglet model restricted in dietary amino acids (AA), our objective was to compare efficacy and safety of a standard formula with a low-AA formula containing an adjusted AA composition. Three to seven day-old piglets (Landrace x Yorkshire x Duroc) were fed one of four iso-energetic AA-based formulas for 14 d (700 kJ/(kg BW.d). The formulas contained a set control amount (44 g/L) and composition of AA referred to as the experimental standard (ST-100, n=22), or 20% or 50% less total AA (respectively, ST-80, n=19 and ST-50, n=13), or 20% less total AA with an adjusted EAA composition (O-80, n=17). A series of clinical and paraclinical endpoints were measured. Growth velocity was comparable for ST-100, O-80 and ST-80 (all about 15 g/(kg.d)), whereas ST-50 had a markedly lower weight gain relative to all groups (all P is less than 0.05). Relative to ST-100, all groups with reduced AA intake showed about 16% reduction in plasma albumin and about 30% reduction in plasma urea (both P is less than 0.05). The absolute leucine oxidation rate was about 30% lower for O-80 than for ST-100 piglets (P is less than 0.05). In conclusion, these data show that a 20% reduction in total AA intake for both the control (ST-80) and the adjusted AA (O-80) formula did not have any short-term adverse effects on growth in artificially-reared, amino acids-restricted piglets. The lower absolute leucine oxidation rate observed in O-80, would support the development of an infant formula with an improved AA composition and a moderate reduction in total protein to support adequate growth in healthy infants.