scholarly journals 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

2020 ◽  
Vol 112 (6) ◽  
pp. 1468-1484 ◽  
Author(s):  
Grith Højfeldt ◽  
Jacob Bülow ◽  
Jakob Agergaard ◽  
Ali Asmar ◽  
Peter Schjerling ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Turnover ◽  
Protein Intake ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
High Protein ◽  
Whole Body ◽  
Body Protein ◽  
Protein Absorption ◽  
Fasted State

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 D8-phenylalanine and D2-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 μmol · 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 protein loss in the fasted state. This was not compensated for in the 4-h postprandial period after intake of a meal high in protein. This trial was registered at clinicaltrials.gov as NCT02587156.

Regional muscle and adipose tissue amino acid metabolism in lean and obese women

2002 ◽  
Vol 282 (4) ◽  
pp. E931-E936 ◽  
Author(s):  
Bruce W. Patterson ◽  
Jeffrey F. Horowitz ◽  
Guoyao Wu ◽  
Malcolm Watford ◽  
Simon W. Coppack ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Amino Acid ◽  
Abdominal Obesity ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Fat Free Mass ◽  
Whole Body ◽  
Obese Women ◽  
Body Protein ◽  
Isotope Tracer

The effect of obesity on regional skeletal muscle and adipose tissue amino acid metabolism is not known. We evaluated systemic and regional (forearm and abdominal subcutaneous adipose tissue) amino acid metabolism, by use of a combination of stable isotope tracer and arteriovenous balance methods, in five lean women [body mass index (BMI) <25 kg/m2] and five women with abdominal obesity (BMI 35.0–39.9 kg/m2; waist circumference >100 cm) who were matched on fat-free mass (FFM). All subjects were studied at 22 h of fasting to ensure that the subjects were in net protein breakdown during this early phase of starvation. Leucine rate of appearance in plasma (an index of whole body proteolysis), expressed per unit of FFM, was not significantly different between lean and obese groups (2.05 ± 0.18 and 2.34 ± 0.04 μmol · kg FFM−1 · min−1, respectively). However, the rate of leucine release from forearm and adipose tissues in obese women (24.0 ± 4.8 and 16.6 ± 6.5 nmol · 100 g−1 · min−1, respectively) was lower than in lean women (66.8 ± 10.6 and 38.6 ± 7.0 nmol · 100 g−1 · min−1, respectively; P < 0.05). Approximately 5–10% of total whole body leucine release into plasma was derived from adipose tissue in lean and obese women. The results of this study demonstrate that the rate of release of amino acids per unit of forearm and adipose tissue at 22 h of fasting is lower in women with abdominal obesity than in lean women, which may help obese women decrease body protein losses during fasting. In addition, adipose tissue is a quantitatively important site for proteolysis in both lean and obese subjects.

Exercise-Mediated Peripheral Tissue and Whole-Body Amino Acid Metabolism during Intravenous Feeding in Normal Man

1989 ◽  
Vol 77 (1) ◽  
pp. 113-120 ◽  
Author(s):  
James D. Albert ◽  
Dwight E. Matthews ◽  
Adrian Legaspi ◽  
Kevin J. Tracey ◽  
Malayappa Jeevanandam ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Submaximal Exercise ◽  
Peripheral Tissue ◽  
Whole Body ◽  
Total Amino Acid ◽  
Body Protein ◽  
Daily Exercise ◽  
Amino Acid Flux

1. The effect of a daily submaximal exercise regimen on whole-body and peripheral tissue amino acid metabolism during weight-stable intravenous feeding (IVF) was evaluated in 11 normal volunteers. Five of the subjects performed 1 h of daily bicycle exercise at 75 W during IVF, while the remaining six subjects received IVF without daily exercise. Body nitrogen balance, leg and forearm plasma amino acid flux and whole-body kinetics were measured before and on day 10 of IVF using a [1-13C]leucine and [15N]glycine tracer. 2. At the end of the IVF period, exercised subjects demonstrated leg uptake of total amino acids (237 ± 103 nmol min−1 100 ml−1 of tissue, mean ± sem) which was significantly (P < 0.05) different than in non-exercised subjects (− 1101 ± 253 nmol min−1 100 ml−1 of tissue). 3. In the non-exercised forearm, a significant (P < 0.05) decrease in total amino acid flux was observed in exercised subjects (− 162 ± 88 nmol min−1 100 ml−1 of tissue) compared with non-exercised subjects (−460 ± 105 nmol min−1 100 ml−1 of tissue) on day 10 of IVF. 4. Efflux of 3-methylhistidine significantly (P < 0.05) decreased from the leg in those subjects who performed daily exercise (−0.29 ± 0.12 nmol min−1 100 ml−1 of tissue) compared with those subjects receiving IVF without daily exercise (− 1.46 ± 0.35 nmol min−1 100 ml−1 of tissue). 5. Although IVF increased whole-body leucine turnover in both exercised and non-exercised subjects, only exercised subjects demonstrated a significant (P < 0.05) increase in leucine oxidation which was proportionate to an increased muscle uptake of leucine. Whole-body protein breakdown, as assessed by [15N]glycine, was significantly (P < 0.05) decreased in exercised subjects compared with non-exercised subjects during IVF. 6. These data demonstrate that daily submaximal exercise produced a systemic as well as limb-specific enhancement of amino acid balance in muscle, providing an anti-catabolic response under conditions of partial immobility induced by hospitalization.

Amino acid metabolism after intense exercise

1990 ◽  
Vol 258 (2) ◽  
pp. E249-E255 ◽  
Author(s):  
J. T. Devlin ◽  
I. Brodsky ◽  
A. Scrimgeour ◽  
S. Fuller ◽  
D. M. Bier
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Recovery Period ◽  
Whole Body ◽  
Protein Breakdown ◽  
Body Protein ◽  
Leucine Oxidation

We studied postexercise amino acid metabolism, in the whole body and across the forearm. Seven volunteers were infused with L-[alpha-15N]lysine and L-[1-13C]-leucine twice [one time during 3 h after cycle exercise (75% VO2max), and one time in the resting state]. Whole body protein breakdown was estimated from dilution of L-[alpha-15N]lysine and L-[1-13C]ketoisocaproic acid (KIC) enrichments in plasma. Leucine oxidation was calculated from 13CO2 enrichments in expired air. Whole body protein breakdown was not increased above resting levels during the recovery period. Leucine oxidation was decreased after exercise (postexercise 13 +/- 2.3 vs. resting 19 +/- 3.2 mumol.kg-1.h-1; P less than 0.02), while nonoxidative leucine disposal was increased (115 +/- 6.1 vs. 103 +/- 5.6 micrograms.kg-1.min-1; P less than 0.02). After exercise, forearm net lysine balance was unchanged (87 +/- 25 vs. 93 +/- 28 nmol.100 ml-1.min-1), but there were decreases in forearm muscle protein degradation (219 +/- 51 vs. 356 +/- 85 nmol.100 ml-1.min-1; P less than 0.05) and synthesis (132 +/- 41 vs. 255 +/- 69 nmol.100 ml-1.min-1; P less than 0.01). In conclusion, after exercise 1) whole body protein degradation is not increased, 2) leucine disposal is directed away from oxidative and toward nonoxidative pathways, 3) forearm protein synthesis is decreased. Postexercise increases in whole body protein synthesis occur in tissues other than nonexercised muscle.

Nitrogen Homoeostasis in man: The Diurnal Responses of Protein Synthesis and Degradation and Amino Acid Oxidation to Diets with Increasing Protein Intakes

1994 ◽  
Vol 86 (1) ◽  
pp. 103-118 ◽  
Author(s):  
Paul J. Pacy ◽  
Gill M. Price ◽  
David Halliday ◽  
Marcello R. Quevedo ◽  
D. Joe Millward
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Dietary Protein ◽  
Protein Turnover ◽  
Protein Intake ◽  
Whole Body ◽  
Body Protein ◽  
Fed State ◽  
Leucine Kinetics ◽  
Synthesis And Degradation

1. The diurnal changes in whole body protein turnover associated with the increasing fasting body nitrogen (N) losses and feeding gains with increasing protein intake were investigated in normal adults. [13C]Leucine, [2H5]phenylalanine and [2H2]tyrosine kinetics, were measured during an 8h primed, continuous infusion during the fasting and feeding phase together with fed-state N turnover assessed with [15N]glycine after 12 days of adaptation to diets containing 0.36 (LP), 0.77 (MP), 1.59 (GP) and 2.07 (HP) g of protein day−1 kg−1. Measurements were also made of fasting and fed resting metabolic rate and plasma hormone levels. 2. Resting metabolic rate in the fasted and fed state was not influenced by dietary protein intake, but was increased by feeding (11-13%, P <0.01) with no influence of dietary protein concentration. Fasting plasma insulin levels were not influenced by protein intake and were increased by feeding independent of protein intake. Fasted but not fed values of insulinlike growth factor-1 increased with protein intake, although no feeding response was observed. Thyroid hormones (free and total tri-iodothyronine) did not change in any state. 3. For leucine with increasing protein intake the increasing fasting losses reflected increasing rates of protein degradation, although the changes were small and only significant between GP and MP intakes. The increasing leucine gain on feeding was associated with increasing rates of protein synthesis and falling rates of protein degradation, reflecting a progressive inhibition of degradation with feeding, and a change from inhibition of synthesis (LP diet) to stimulation (GP and HP diets). Mean daily rates of synthesis and degradation did not change with protein intake. 4. Phenylalanine and tyrosine kinetics were calculated from adjusted values based on leucine kinetics and published data of the hepatic/plasma enrichment ratio. With the increased protein intake, the increasing fasting losses of phenylalanine (GP > MP) were mediated by increasing rates of degradation (paired t-tests). The increasing phenylalanine gain (GP > MP > LP) was due to increasing fed-state rates of synthesis and falling rates of degradation, reflecting a progressive inhibition of degradation, a stimulation of hydroxylation and a variable response of synthesis ranging from inhibition at the lowest intake to stimulation at higher intakes. For tyrosine a similar progressive inhibition of degradation with intake was shown. Mean daily rates of synthesis and degradation (phenylalanine) and degradation (tyrosine) did not change with protein intake. 5. Estimation of protein turnover from 15N excretion in urea and ammonia during 9 h after 1 h intravenous infusion of [15N]glycine in the fed state on the LP, MP and GP diets indicated that neither synthesis nor degradation were influenced by dietary protein level. Synthesis estimated from 15N kinetics was significantly correlated with that determined from leucine kinetics (r = 0.78, n = 14, P <0.01) and from phenylalanine kinetics (r = 0.53, n = 14, P <0.05), and degradation estimated from 15N kinetics was significantly correlated with that determined from leucine kinetics (r = 0.60, n = 14, P <0.05). Thus the [15N]glycine, [13C]leucine and [2H5]phenylalanine methods gave broadly comparable results. 6. We conclude that the feeding response of protein synthesis, degradation and amino acid oxidation reflects the combined impact of insulin and tissue amino acid levels with insulin inhibiting degradation and with amino acids both stimulating synthesis and oxidation and also further inhibiting degradation. Although the dietary protein level influences the extent of these feeding responses, it does not influence the mean daily rate of protein turnover. The rate of whole body protein turnover per se is unlikely to provide an indicator of protein nutritional status.

New advances in stable tracer methods to assess whole-body protein and amino acid metabolism

2019 ◽  
Vol 22 (5) ◽  
pp. 337-346 ◽  
Author(s):  
Mariëlle P.K.J. Engelen ◽  
Gabriella A.M. Ten Have ◽  
John J. Thaden ◽  
Nicolaas E.P. Deutz
Keyword(s):  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Whole Body ◽  
Body Protein ◽  
Tracer Methods

scholarly journals Interactive effects of aging and aerobic capacity on energy metabolism–related metabolites of serum, skeletal muscle, and white adipose tissue

GeroScience ◽  
2021 ◽  
Author(s):  
Haihui Zhuang ◽  
Sira Karvinen ◽  
Timo Törmäkangas ◽  
Xiaobo Zhang ◽  
Xiaowei Ojanen ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Amino Acid ◽  
White Adipose Tissue ◽  
Aerobic Capacity ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Disease Risk ◽  
Whole Body ◽  
Whole Body Metabolism

AbstractAerobic capacity is a strong predictor of longevity. With aging, aerobic capacity decreases concomitantly with changes in whole body metabolism leading to increased disease risk. To address the role of aerobic capacity, aging, and their interaction on metabolism, we utilized rat models selectively bred for low and high intrinsic aerobic capacity (LCRs/HCRs) and compared the metabolomics of serum, muscle, and white adipose tissue (WAT) at two time points: Young rats were sacrificed at 9 months of age, and old rats were sacrificed at 21 months of age. Targeted and semi-quantitative metabolomics analysis was performed on the ultra-pressure liquid chromatography tandem mass spectrometry (UPLC-MS) platform. The effects of aerobic capacity, aging, and their interaction were studied via regression analysis. Our results showed that high aerobic capacity is associated with an accumulation of isovalerylcarnitine in muscle and serum at rest, which is likely due to more efficient leucine catabolism in muscle. With aging, several amino acids were downregulated in muscle, indicating more efficient amino acid metabolism, whereas in WAT less efficient amino acid metabolism and decreased mitochondrial β-oxidation were observed. Our results further revealed that high aerobic capacity and aging interactively affect lipid metabolism in muscle and WAT, possibly combating unfavorable aging-related changes in whole body metabolism. Our results highlight the significant role of WAT metabolism for healthy aging.

Effect of variable protein intake on whole-body protein turnover in young men and women

1995 ◽  
Vol 61 (1) ◽  
pp. 69-74 ◽  
Author(s):  
D L Pannemans ◽  
D Halliday ◽  
K R Westerterp ◽  
A D Kester
Keyword(s):  
Protein Turnover ◽  
Protein Intake ◽  
Young Men ◽  
Whole Body ◽  
Body Protein ◽  
Men And Women

Whole-body leucine and lysine metabolism: response to dietary protein intake in young men

1981 ◽  
Vol 240 (6) ◽  
pp. E712-E721 ◽  
Author(s):  
K. J. Motil ◽  
D. E. Matthews ◽  
D. M. Bier ◽  
J. F. Burke ◽  
H. N. Munro ◽  
...  
Keyword(s):  
Amino Acid ◽  
Dietary Protein ◽  
Protein Intake ◽  
Whole Body ◽  
Dietary Protein Intake ◽  
Body Protein ◽  
Fed State ◽  
Amino Acid Requirements ◽  
Maintenance Requirements ◽  
Lysine Metabolism

Whole-body leucine and lysine metabolism was explored in young adult men by a primed constant intravenous infusion of a mixture of L-[1–13C]leucine and L-[alpha-15N]lysine over a 4-h period. Subjects were studied after an overnight fast (postabsorptive state) or while consuming hourly meals (fed state) after adaptation to diets providing either a surfeit level of protein (1.5 g.kg body-1.day-1), a level approximating maintenance requirements (marginal intake) (0.6 g.kg body wt-1.day-1), or a grossly inadequate level (0.1 g.kg-1.day-1). The change in protein intake from a marginal to a surfeit level was associated with an increased leucine flux and incorporation of leucine into body protein. In the fed state, oxidation of leucine increased sharply and release of leucine from tissue protein diminished. When dietary protein intake was reduced from the requirement to inadequate level, leucine flux and body protein synthesis and protein breakdown were reduced, together with a smaller reduction in leucine oxidation. The response of the metabolism of [15N]lysine was responsible for maintenance of leucine and other essential amino acid economy, and they appear to be related to the nitrogen and amino acid requirements of the subject. These findings also demonstrate an effect of meals, modulated by their protein content, on the dynamics of whole-body amino acid metabolism.

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