Excess energy and nitrogen balance at protein intakes above the requirement level in young men

doi:10.1093/ajcn/48.4.1015

The American Journal of Clinical Nutrition

Volume 48, Issue 4, October 1988, Pages 1015-1022

https://doi.org/10.1093/ajcn/48.4.1015 Get rights and content

ABSTRACT

Effects of excess energy on nitrogen balance at above the safe level of protein intake were studied in six young men. They were given test diets with a fixed protein intake of 1.2 g.kg-1.d-1 but with three successive energy (E) levels: at maintenance (1.0 E), 15% above maintenance (1.15 E) and 30% above maintenance (1.3 E), both in ascending (1.0 E, 1.15 E, 1.3 E) and descending (1.3 E, 1.15 E, 1.0 E) sequences. Duration of each dietary period was 10 d. N balance increased from 7.2 to 23.8 to 33.3 mg N.kg-1.d-1 in the ascending series and decreased from 27.8 to 17.6 to 4.8 mg N.kg-1.d-1 in the descending series. The changes in N balance per 100 kcal change in energy intake ranged between 144 and 243 mg with smaller changes at higher energy levels. Biological value and net protein utilization of the dietary protein were positively correlated with energy intake in both the ascending series and the descending series (p less than 0.001).

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The ratio of energy expenditure to nitrogen loss in diverse patient groups - A systematic review
2012, Clinical Nutrition
The ratio of energy expenditure to nitrogen loss respectively of energy to nitrogen provision (E/N) is considered a valuable tool in the creation of an enteral or parenteral formulation. Specific E/N ratios for parenteral nutrition (PN) have not yet been clearly defined. To determine the range of energy expenditure, nitrogen (protein) losses, and E/N ratios for various patient groups, we performed a systematic review of the literature.
Medline 1950–2011 was searched for all studies on patients or healthy controls reporting energy expenditure and nitrogen loss at the same time.
We identified 53 studies with 91 cohorts which comprised 1107 subjects. Mean TEE ± standard deviation (SD) was 31.2 ± 7.2 kcal/kg BW/day in patients (n = 881) and 35.6 ± 4.3 kcal/kg BW/day in healthy controls (n = 266). Mean total protein loss (TPL) was 1.50 ± 0.57 g/kg BW/day in patients and 0.94 ± 0.24 g/kg BW/day in healthy controls. A non-linear significant correlation was found between TPL and the E/N ratio.
The E/N ratio is not a constant value but decreases continuously with increasing protein loss. These variations should be considered in the nutritional support of patients.
Rendiment esportiu: Glucogen muscular i consum proteic
2008, Apunts Medicina de l'Esport
Para conseguir un óptimo rendimiento deportivo mediante el control de parámetros relacionados directa o indirectamente con la ingesta, puede resultar de gran importancia conocer y saber controlar el entramado metabólico relacionado con el glucógeno muscular y la optimización del consumo proteico.
La recuperación de las reservas de glucógeno tras la realización del ejercicio físico es un proceso lento que puede llevar de 24 a 48 h según las pérdidas producidas. La velocidad de resíntesis del glucógeno es máxima en las 2 primeras horas tras la realización del ejercicio físico. El proceso de resíntesis glucogénico podría acelerarse por la ingestión simultánea de hidratos de carbono-proteína o hidratos de carbono-aminoácidos, pudiendo ser una buena opción tomar nada más acabar el ejercicio físico una mezcla de sacarosa o azúcar de mesa (1 g/kg) con suero de leche (0,5 g/kg). Mediante la supercompensación del glucógeno o sobrecarga de hidratos de carbono se pretende conseguir aumentar las reservas de glucógeno por encima de los valores fisiológicos, de tal forma que el atleta tenga un extra energético que le pueda ayudar a mejorar su rendimiento deportivo. Esta ganancia va acompañada de agua que hace que aumente el volumen y vistosidad muscular, motivo por el cual se usa con frecuencia por los competidores de culturismo. Existen 3 técnicas se similar eficacia, la de Astrand, Sherman/Costill y Fairchild/Fournier siendo la última la más rápida y facil de realizar.
El consumo de proteínas en el deportista es necesario pero no debería representar más del 15-20% del consumo calórico diario total, ya que cuando se sobrepasa este umbral la proteína pierde su efecto anabólico. Así, si el deportista tiene como objetivo aumentar la masa muscular, se debería aumentar el aporte calórico total de forma equilibrada y no el procedente únicamente de las proteínas.
To achieve optimal athletic performance by controlling factors directly or indirectly associated with the intake, knowledge of how to control the metabolic processes associated with muscle glycogen and protein intake are highly important. Recovery of glycogen stores after exercise is a slow process, and complete recovery may take 24-48 h after exercise has ceased, depending on how much glycogen has been lost. The maximum rate of glycogen resynthesis occurs in the first 2 hours after the workout. The rate of muscle glycogen resynthesis could be accelerated through simultaneous intake of carbohydrate-proteins or carbohydrate-amino acids, effective combinations after the workout being sucrose or table sugar (1 g/kg) and whey protein (0.5 g/kg). Glycogen supercompensation or carbohydrate loading aims to raise glycogen storage above physiological levels to increase the duration of carbohydrate availability to exercising muscles, thus enhancing performance. The stored glycogen is accompanied by water, which increases muscle volume and definition, and consequently this strategy is frequently used by bodybuilding competitors. There are three supercompensation methods: the Astrand, Sherman/Costill and Fairchild/Fournier, they have the same effectiveness but the least option is the quickest and easier way.
Protein intake is essential for athletes but should account for no more than 15-20% of the daily calorie intake because protein loses its anabolic profile when consumed in quantities higher than this threshold. Thus, athletes aiming to acquire new muscle mass should increase total calorie intake by following a balanced diet and should not aim to increase calories from protein alone.
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Acute endurance exercise results in the oxidation of several amino acids. The total amount of amino acid oxidation during endurance exercise amounts to only 1–6% of the total energy cost of exercise. The branched chain amino acid, leucine, has been most often studied in relation to endurance exercise. Leucine is oxidized by the enzyme, branched-chain oxo-acid dehydrogenase (BCOAD). BCOAD is relatively inactive at rest (∼4–7%) and is activated at the onset of exercise by dephosphorylation (to about 25%). After a period of endurance exercise training, the activation of BCOAD and amino acid oxidation are attenuated, however the total amount of BCOAD enzyme is up-regulated. A low energy and/or carbohydrate intake will increase amino acid oxidation and total protein requirements. With adequate energy and carbohydrate intake, low to moderate intensity endurance activity has little impact on dietary protein requirements and 1.0 gPRO/kg/d is sufficient. The only situation where dietary protein requirements exceed those for relatively sedentary individuals is in top sport athletes where the maximal requirement is ∼1.6 gPRO/kg/d. Although most endurance athletes get enough protein to support any increased requirements, those with low energy or carbohydrate intakes may require nutritional advice to optimize dietary protein intake.
Attenuation of the protein wasting associated with bed rest by branched-chain amino acids
1999, Nutrition
Bed rest is generally accepted as being an appropriate ground-based model for human spaceflight. The objectives of this study were to test the hypothesis that increasing the amount of branched-chain amino acids (BCAAs) in the diet could attenuate the protein loss associated with bed rest. Nineteen healthy subjects were randomized into two groups according to diet. During the 6 d of bed rest, the diets were supplemented with either 30 mmol/d each of three non-essential amino acids, glycine, serine, and alanine (control group), or with 30 mmol/d each of the BCAAs, leucine, isoleucine, and valine (BCAA group). Nutrition was supplied as a commercially available defined formula diet at a rate of 1.3 × REE. Nitrogen (N) balance and urinary 3-MeH excretion were determined for the 6 d. In our results, the urine-based estimate of N balance was 22.2 ± 14.4 (n = 9) mg N · kg⁻¹ · d⁻¹ and 60.5 ± 10.1 mg (n = 8) N · kg⁻¹ · d⁻¹ for the control and BCAA-supplemented groups, respectively (P < 0.05). Urinary 3-MeH excretion was unchanged in both groups with bed rest. We conclude that BCAA supplementation attenuates the N loss during short-term bed rest.
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2018, Journal of Parenteral and Enteral Nutrition
Cumulative Muscle Protein Synthesis and Protein Intake Requirements
2016, Annual Review of Nutrition

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Excess energy and nitrogen balance at protein intakes above the requirement level in young men

ABSTRACT

Am J Clin Nutr

Metabolism

J Nutr

J Am Diet Assoc

Am Heart J

J Nutr

J Nutr

J Nutr

Am J Clin Nutr

Am J Clin Nutr

Studies on protein requirements of young men fed egg protein and rice protein with excess and maintenanceenergyintakes.

J Nutr

Human protein require- ments: the effects ofvariations in energy intake within the mainte- nance range.

Am J Clin Nutr

Carbohydrate and fat as factors in protein utilization and metabolism.

Physiol Rev

The influence ofenergy intake on protein metabolism.

Biochem J

Effect of varying energy and protein intake on nitrogen balance in adults engaged in heavy manual labour.

Br J Nutr