scholarly journals The Anabolic Response to Dietary Protein Is Not Limited by the Maximal Stimulation of Protein Synthesis in Healthy Older Adults: A Randomized Crossover Trial

Nutrients ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3276
Author(s):  
Sanghee Park ◽  
Jiwoong Jang ◽  
Myung Dong Choi ◽  
Yun-A Shin ◽  
Scott Schutzler ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Protein Synthesis ◽  
Protein Intake ◽  
Whole Body ◽  
Synthesis Rate ◽  
Mixed Meal ◽  
Protein Kinetics ◽  
Anabolic Response ◽  
Body Protein

We have recently demonstrated in young adults that an anabolic response with mixed meal protein intake above ~35 g/meal, previously recognized as an “optimal” protein dose, was further stimulated. However, it is unknown if this applies to older adults. We therefore examined anabolic response to a mixed meal containing either 35 g (MOD, moderate amount of protein) or 70 g (HIGH, high amount of protein) in a randomized cross-over metabolic study in older adults (n = 8). Primed continuous infusions of L-[2H5] phenylalanine and L-[2H2]tyrosine were performed to determine whole-body protein kinetics and muscle protein fractional synthesis rate (MPS) in basal fasted and fed states. Whole-body protein kinetics (NB, net protein balance; PS, protein synthesis; PB, protein breakdown) and MPS was expressed as changes from the baseline post-absorptive state. Consistent with our previous findings in young adults, both feedings resulted in a positive NB, with HIGH being more positive than MOD. Furthermore, NB (expressed as g protein∙240 min) increased linearly with an increasing amount of protein intake, expressed relative to lean body mass. The positive NB was achieved due mainly to the suppression of PB in both MOD and to a greater extent HIGH, while PS was only increased in HIGH. Consistent with the whole-body data, MPS was significantly higher in HIGH than MOD. Plasma concentrations of essential amino acids and insulin were greater in HIGH vs. MOD. We conclude that in the context of mixed meals, whole-body anabolic response linearly increases with increasing protein intake primarily through the suppression of PB, and MPS was further stimulated with protein intake above the previously considered “optimal” protein dose in older adults.

scholarly journals The anabolic response to a meal containing different amounts of protein is not limited by the maximal stimulation of protein synthesis in healthy young adults

2016 ◽  
Vol 310 (1) ◽  
pp. E73-E80 ◽  
Author(s):  
Il-Young Kim ◽  
Scott Schutzler ◽  
Amy Schrader ◽  
Horace J. Spencer ◽  
Gohar Azhar ◽  
...  
Keyword(s):  
Young Adults ◽  
Protein Synthesis ◽  
Protein Intake ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Human Subjects ◽  
Whole Body ◽  
Protein Kinetics ◽  
Body Protein ◽  
Stimulation Of

We have determined whole body protein kinetics, i.e., protein synthesis (PS), breakdown (PB), and net balance (NB) in human subjects in the fasted state and following ingestion of ∼40 g [moderate protein (MP)], which has been reported to maximize the protein synthetic response or ∼70 g [higher protein (HP)] protein, more representative of the amount of protein in the dinner of an average American diet. Twenty-three healthy young adults who had performed prior resistance exercise (X-MP or X-HP) or time-matched resting (R-MP or R-HP) were studied during a primed continuous infusion of l-[2H5]phenylalanine and l-[2H2]tyrosine. Subjects were randomly assigned into an exercise (X, n = 12) or resting (R, n = 11) group, and each group was studied at the two levels of dietary protein intake in random order. PS, PB, and NB were expressed as increases above the basal, fasting values (mg·kg lean body mass−1·min−1). Exercise did not significantly affect protein kinetics and blood chemistry. Feeding resulted in positive NB at both levels of protein intake: NB was greater in response to the meal containing HP vs. MP ( P < 0.00001). The greater NB with HP was achieved primarily through a greater reduction in PB and to a lesser extent stimulation of protein synthesis (for all, P < 0.0001). HP resulted in greater plasma essential amino acid responses ( P < 0.01) vs. MP, with no differences in insulin and glucose responses. In conclusion, whole body net protein balance improves with greater protein intake above that previously suggested to maximally stimulating muscle protein synthesis because of a simultaneous reduction in protein breakdown.

Impairment of albumin and whole body postprandial protein synthesis in compensated liver cirrhosis

2002 ◽  
Vol 282 (2) ◽  
pp. E304-E311 ◽  
Author(s):  
P. Tessari ◽  
R. Barazzoni ◽  
E. Kiwanuka ◽  
G. Davanzo ◽  
G. De Pergola ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Liver Cirrhosis ◽  
Disease Stage ◽  
Whole Body ◽  
Synthesis Rate ◽  
Albumin Concentration ◽  
Mixed Meal ◽  
Body Protein ◽  
Control Subjects ◽  
Class B

To investigate the anabolic effects of feeding in cirrhosis, we measured albumin fractional synthesis rate (FSR) and whole body protein synthesis in six nondiabetic patients with stable liver cirrhosis (three in the Child-Pugh classification Class A, three in Class B) and in seven normal control subjects, before and after administration of a 4-h mixed meal. Leucine tracer precursor-product relationships and whole body kinetics were employed at steady state. Basal levels of postabsorptive albumin concentration and FSR, whole body leucine rate of appearance, oxidation, and nonoxidative leucine disposal (NOLD, ≈protein synthesis) were similar in the two groups. However, after the meal, in the patients neither albumin FSR (from 8.5 ± 1.5 to 8.8 ± 1.8 %/day) nor NOLD (from 1.69 ± 0.22 to 1.55 ± 0.26 μmol · kg−1· min−1) changed ( P = nonsignificant vs. basal), whereas they increased in control subjects (albumin FSR: from 10.9 ± 1.5 to 15.9 ± 1.9 %/day, P < 0.002; NOLD: from 1.80 ± 0.14 to 2.10 ± 0.19 μmol · kg−1· min−1, P = 0.032). Thus mixed meal ingestion did not stimulate either albumin FSR or whole body protein synthesis in compensated liver cirrhosis. The mechanism(s) maintaining normoalbuminemia at this disease stage need to be further investigated.

scholarly journals Comparison of basal whole‐body protein kinetics and muscle protein synthesis between young and older adults

2020 ◽  
Vol 8 (23) ◽  
Author(s):  
Katie R. Hirsch ◽  
David D. Church ◽  
Il‐Young Kim ◽  
Sanghee Park ◽  
Robert R. Wolfe ◽  
...  
Keyword(s):  
Older Adults ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Whole Body ◽  
Protein Kinetics ◽  
Body Protein

scholarly journals Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults

2015 ◽  
Vol 308 (1) ◽  
pp. E21-E28 ◽  
Author(s):  
Il-Young Kim ◽  
Scott Schutzler ◽  
Amy Schrader ◽  
Horace Spencer ◽  
Patrick Kortebein ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
G Protein ◽  
Protein Intake ◽  
Muscle Protein ◽  
Distribution Patterns ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Balance ◽  
Body Protein ◽  
Net Protein

To examine whole body protein turnover and muscle protein fractional synthesis rate (MPS) following ingestions of protein in mixed meals at two doses of protein and two intake patterns, 20 healthy older adult subjects (52–75 yr) participated in one of four groups in a randomized clinical trial: a level of protein intake of 0.8 g (1RDA) or 1.5 g·kg−1·day−1 (∼2RDA) with uneven (U: 15/20/65%) or even distribution (E: 33/33/33%) patterns of intake for breakfast, lunch, and dinner over the day (1RDA-U, 1RDA-E, 2RDA-U, or 2RDA-E). Subjects were studied with primed continuous infusions of l-[2H5]phenylalanine and l-[2H2]tyrosine on day 4 following 3 days of diet habituation. Whole body protein kinetics [protein synthesis (PS), breakdown, and net balance (NB)] were expressed as changes from the fasted to the fed states. Positive NB was achieved at both protein levels, but NB was greater in 2RDA vs. 1RDA (94.8 ± 6.0 vs. 58.9 ± 4.9 g protein/750 min; P = 0.0001), without effects of distribution on NB. The greater NB was due to the higher PS with 2RDA vs. 1RDA (15.4 ± 4.8 vs. −18.0 ± 8.4 g protein/750 min; P = 0.0018). Consistent with PS, MPS was greater with 2RDA vs. 1RDA, regardless of distribution patterns. In conclusion, whole body net protein balance was greater with protein intake above recommended dietary allowance (0.8 g protein·kg−1·day−1) in the context of mixed meals, without demonstrated effects of protein intake pattern, primarily through higher rates of protein synthesis at whole body and muscle levels.

Protein turnover in man measured with 15N: comparison of end products and dose regimes.

1978 ◽  
Vol 235 (2) ◽  
pp. E165 ◽  
Author(s):  
J C Waterlow ◽  
M H Golden ◽  
P J Garlick
Keyword(s):  
Protein Synthesis ◽  
Oral Dosage ◽  
Whole Body ◽  
Synthesis Rate ◽  
Obese Patients ◽  
Simple Method ◽  
Body Protein ◽  
End Products ◽  
Collection Period ◽  
Comparative Information

Whole-body protein synthesis was measured with [15N]glycine in malnourished and recovered infants and in obese patients. Comparisons were made: 1) between results obtained with single (S) and repeated (R) oral dosage of tracer; and 2) between urea and ammonia as end products. In the infants S and R gave similar values for the synthesis rate. With both methods of dosage, the values obtained with NH3 as end product were about two-thirds of those with urea. It is suggested that the cause of this result is that glycine contributes preferentially to the formation of urinary NH3. With NH3 as end product, a collection period of 12 h has been found to be suitable. With urea it is not possible to define an appropriate collection period. The combination of single dose of [15N]glycine with urinary NH3 as end product provides a simple method for measuring whole-body protein synthesis under clinical and field conditions. It can be repeated at short intervals and can give useful comparative information provided that conditions are carefully standardized. The reproducibility so far is +/- 13%.

scholarly journals Contribution of whole-body protein synthesis to basal metabolism in layer and broiler chickens

1987 ◽  
Vol 57 (2) ◽  
pp. 269-277 ◽  
Author(s):  
T. Muramatsu ◽  
Y. Aoyagi ◽  
J. Okumura ◽  
I. Tasaki
Keyword(s):  
Protein Synthesis ◽  
Broiler Chickens ◽  
Whole Body ◽  
Synthesis Rate ◽  
Body Protein ◽  
Fractional Synthesis Rate ◽  
Degradation Rates ◽  
Fractional Synthesis ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

1. The effect of starvation on whole-body protein synthesis and on the contribution of protein synthesis to basal metabolic rate was investigated in young chickens (Expt 1). Strain differences between layer and broiler chickens in whole-body protein synthesis and degradation rates were examined when the birds were starved (Expt 2).2. In Expt 1, 15-d-old White Leghorn male chickens were used, while in Expt 2 Hubbard (broiler) and White Leghorn (layer) male chickens at 14 d of age were used. They were starved for 4 d, and heat production was determined by carcass analysis after 2 and 4 d of starvation. Whole-body protein synthesis rates were measured on 0, 2 and 4 d of starvation (Expt 1), and on 0 and 4 d of starvation (Expt 2).3. The results showed that starving reduced whole-body protein synthesis in terms of fractional synthesis rate and the amount synthesized. Whole-body protein degradation was increased by starvation both in terms of fractional synthesis rate and the amount degraded on a per kg body-weight basis.4. Reduced fractional synthesis rate of protein in the whole body was accounted for by reductions in both protein synthesis per unit RNA and RNA:protein ratio.5. In the fed state, whole-body protein synthesis and degradation rates, whether expressed as fractional rates or amounts per unit body-weight, tended to be higher in layer than in broiler chickens. In the starved state, the difference in the rate of protein synthesis between the two strains virtually disappeared, while the degradation rates were higher in layer than in broiler birds.6. Based on the assumed value of 3.56 kJ/g protein synthesized (Waterlow et al. 1978), the heat associated with whole-body protein synthesis in the starved state was calculated to range from 14 to 17% of the basal metabolic rate with no strain difference between layer and broiler chickens.

Dietary crude protein intake influences rates of whole-body protein synthesis in weanling horses

2014 ◽  
Vol 202 (2) ◽  
pp. 236-243 ◽  
Author(s):  
S.L. Tanner ◽  
A.L. Wagner ◽  
R.N. Digianantonio ◽  
P.A. Harris ◽  
J.T. Sylvester ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Intake ◽  
Crude Protein ◽  
Whole Body ◽  
Body Protein ◽  
Dietary Crude Protein

Effect of spaceflight on human protein metabolism

1993 ◽  
Vol 264 (5) ◽  
pp. E824-E828 ◽  
Author(s):  
T. P. Stein ◽  
M. J. Leskiw ◽  
M. D. Schluter
Keyword(s):  
Protein Synthesis ◽  
Nitrogen Balance ◽  
Protein Metabolism ◽  
Space Shuttle ◽  
Single Pulse ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Body Protein ◽  
Space Shuttle Columbia

Nitrogen balance and the whole body protein synthesis rate were measured before, during, and after a 9.5-day spaceflight mission on the space shuttle Columbia. Protein synthesis was measured by the single-pulse [15N]glycine method. Determinations were made 56, 26, and 18 days preflight, on flight days 2 and 8, and on days 0, 6, 14, and 45 postflight. We conclude that nitrogen balance was decreased during spaceflight. The decrease in nitrogen balance was greatest on the 1st day when food intake was reduced and again toward the end of the mission. An approximately 30% increase in protein synthesis above the preflight baseline was found for flight day 8 for all 6 subjects (P < 0.05), indicating that the astronauts showed a stress response to spaceflight.

scholarly journals Increased plasma Gln and Leu Raand inappropriately low muscle protein synthesis rate in AIDS wasting

1998 ◽  
Vol 275 (4) ◽  
pp. E577-E583 ◽  
Author(s):  
Kevin E. Yarasheski ◽  
Jeffrey J. Zachwieja ◽  
Jennifer Gischler ◽  
Jan Crowley ◽  
Mary M. Horgan ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Asymptomatic Group ◽  
Body Protein ◽  
Asymptomatic Subjects ◽  
Muscle Protein Synthesis Rate

Muscle protein wasting occurs in human immunodeficiency virus (HIV)-infected individuals and is often the initial indication of acquired immunodeficiency syndrome (AIDS). Little is known about the alterations in muscle protein metabolism that occur with HIV infection. Nine subjects with AIDS wasting (CD4 < 200/mm3), chronic stable opportunistic infections (OI), and ≥10% weight loss, fourteen HIV-infected men and one woman (CD4 > 200/mm3) without wasting or OI (asymptomatic), and six HIV-seronegative lean men (control) received a constant intravenous infusion of [1-13C]leucine (Leu) and [2-15N]glutamine (Gln). Plasma Leu and Gln rate of appearance (Ra), whole body Leu turnover, disposal and oxidation rates, and [13C]Leu incorporation rate into mixed muscle protein were assessed. Total body muscle mass/fat-free mass was greater in controls (53%) than in AIDS wasting (43%; P = 0.04). Fasting whole body proteolysis and synthesis rates were increased above control in the HIV+ asymptomatic group and in the AIDS-wasting group ( P = 0.009). Whole body Leu oxidation rate was greater in the HIV+ asymptomatic group than in the control and AIDS-wasting groups ( P < 0.05). Fasting mixed muscle protein synthesis rate was increased in the asymptomatic subjects (0.048%/h; P = 0.01) but was similar in AIDS-wasting and control subjects (0.035 vs. 0.037%/h). Plasma Gln Rawas increased in AIDS-wasting subjects but was similar in control and HIV+ asymptomatic subjects ( P < 0.001). These findings suggest that AIDS wasting results from 1) a preferential reduction in muscle protein, 2) a failure to sustain an elevated rate of mixed muscle protein synthesis while whole body protein synthesis is increased, and 3) a significant increase in Gln release into the circulation, probably from muscle. Several interesting explanations for the increased Gln Rain AIDS wasting exist.

Influence of protein intake on whole body and splanchnic leucine kinetics in humans

1997 ◽  
Vol 272 (4) ◽  
pp. E584-E591 ◽  
Author(s):  
M. Cayol ◽  
Y. Boirie ◽  
F. Rambourdin ◽  
J. Prugnaud ◽  
P. Gachon ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Intake ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
The Body ◽  
Whole Body ◽  
Body Protein ◽  
Leucine Kinetics ◽  
Protein X ◽  
Pool Model

The influence of the protein content of the meal on protein turnover was investigated in the splanchnic bed and in the remaining parts of the body in humans. Two groups of five subjects consumed every 20 min a liquid formula providing either 1.5 g protein x kg(-1) x day(-1) (P) or no protein (PF). L-[1-(13)C]leucine and L-[5,5,5-(2)H3]leucine were administered by vein and gut, respectively. An open two-pool model was developed to calculate leucine kinetics in both compartments, with the assumption that the enrichment of the tracers incorporated into very low density lipoprotein apolipoprotein B100 at isotopic steady state could reflect the leucine labeling in the splanchnic region. Nonsplanchnic uptake and release of leucine were not significantly different in the two groups. Within the splanchnic area, leucine uptake was 2.1 times higher in the P than in the PF group (P < 0.01), whereas leucine release was reduced but not significantly (-19%) in the P group compared with the PF group. Moreover, data derived from this model showed that protein intake induced an increase in whole body protein synthesis and no change in whole body protein breakdown. Albumin synthesis, as well as its contribution to whole body protein synthesis, was significantly enhanced by protein intake.

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