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Impact of habituated dietary protein intake on fasting and postprandial whole-body protein turnover and splanchnic amino acid metabolism in elderly men:a randomized, controlled, crossover trial
- Source :
- Højfeldt , G , Bulow , J , Agergaard , J , Asmar , A , Schjerling , P , Simonsen , L , Bulow , J , van Hall , G & Holm , L 2020 , ' Impact of habituated dietary protein intake on fasting and postprandial whole-body protein turnover and splanchnic amino acid metabolism in elderly men : a randomized, controlled, crossover trial ' , American Journal of Clinical Nutrition , vol. 112 , no. 6 , pp. 1468-1484 .
- Publication Year :
- 2020
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Abstract
- Background: Efficacy of protein absorption and subsequent amino acid utilization may be reduced in the elderly. Higher protein intakes have been suggested to counteract this.Objectives: We aimed to elucidate how habituated amounts of protein intake affect the fasted state of, and the stimulatory effect of a protein-rich meal on, protein absorption, whole-body protein turnover, and splanchnic amino acid metabolism.Methods: Twelve men (65-70 y) were included in a double-blinded crossover intervention study, consisting of a 20-d habituation period to a protein intake at the RDA or a high amount [1.1 g . kg lean body mass (LBM)(-)(1) . d(-1) or >2.1 g . kg LBM-1 . d(-1), respectively], each followed by an experimental trial with a primed, constant infusion of D-8-phenylalanine and D-2-tyrosine. Arterial and hepatic venous blood samples were obtained after an overnight fast and repeatedly 4 h after a standardized meal including intrinsically labeled whey protein concentrate and calcium-caseinate proteins. Blood was analyzed for amino acid concentrations and phenylalanine and tyrosine tracer enrichments from which whole-body and splanchnic amino acid and protein kinetics were calculated.Results: High (compared with the recommended amount of) protein intake resulted in a higher fasting whole-body protein turnover with a resultant mean +/- SEM 0.03 +/- 0.01 mu mol . kg LBM-1 . min(-1) lower net balance (P <0.05), which was not rescued by the intake of a protein-dense meal. The mean +/- SEM plasma protein fractional synthesis rate was 0.13 +/- 0.06%/h lower (P <0.05) after habituation to high protein. Furthermore, higher fasting and postprandial amino acid removal were observed after habituation to high protein, yielding higher urea excretion and increased phenylalanine oxidation rates (P <0.01).Conclusions: Three weeks of habituation to high protein intake (>2.1 g protein . kg LBM-1 . d(-1)) led to a significantly higher net pro
Details
- Database :
- OAIster
- Journal :
- Højfeldt , G , Bulow , J , Agergaard , J , Asmar , A , Schjerling , P , Simonsen , L , Bulow , J , van Hall , G & Holm , L 2020 , ' Impact of habituated dietary protein intake on fasting and postprandial whole-body protein turnover and splanchnic amino acid metabolism in elderly men : a randomized, controlled, crossover trial ' , American Journal of Clinical Nutrition , vol. 112 , no. 6 , pp. 1468-1484 .
- Notes :
- application/pdf, English
- Publication Type :
- Electronic Resource
- Accession number :
- edsoai.on1296097633
- Document Type :
- Electronic Resource