Increased Protein Requirements Research Articles

Comment on: Nocturnal Nutritional Supplementation Improves Total Body Protein Status of Patients With Liver Cirrhosis: A Randomized 12‐Month Trial

Patients with liver cirrhosis exhibit early onset of gluconeogenesis after short‐term fasting. This accelerated metabolic reaction to starvation may underlie their increased protein requirements and muscle depletion. A randomized controlled trial was conducted to test the hypothesis that provision of a late‐evening nutritional supplement over a 12‐month period would improve body protein stores in patients with cirrhosis. A total of 103 patients (68 male, 35 female; median age 51, range 28‐74; Child‐Pugh grading: 52A, 31B, 20C) were randomized to receive either daytime (between 0900 and 1900 hours) or nighttime (between 2100 and 0700 hours) supplementary nutrition (710 kcal/day). Primary etiology of liver disease was chronic viral hepatitis (67), alcohol (15), cholestatic (6), and other (15). Total body protein (TBP) was measured by neutron activation analysis at baseline, 3, 6, and 12 months. Total daily energy and protein intakes were assessed at baseline and at 3 months by comprehensive dietary recall. As a percentage of values predicted when well, TBP at baseline was similar for the daytime (85 ± 2[standard error of the mean]%) and nighttime (84 ± 2%) groups. For the nighttime group, significant increases in TBP were measured at 3 (0.38 ± 0.10 kg, P = 0.0004), 6 (0.48 ± 0.13 kg, P = 0.0007), and 12 months (0.53 ± 0.17 kg, P = 0.003) compared to baseline. For the daytime group, no significant changes in TBP were seen. Daily energy and protein intakes at 3 months were higher than at baseline in both groups (P < 0.0001), and these changes did not differ between the groups. Conclusion: Provision of a nighttime feed to patients with cirrhosis results in body protein accretion equivalent to about 2 kg of lean tissue sustained over 12 months. This improved nutritional status may have important implications for the clinical course of these patients. (Hepatology. 2008;48:557‐566.)Plank LD, Gane EJ, Peng S, et al.

Nocturnal nutritional supplementation improves total body protein status of patients with liver cirrhosis: A randomized 12-month trial

Patients with liver cirrhosis exhibit early onset of gluconeogenesis after short-term fasting. This accelerated metabolic reaction to starvation may underlie their increased protein requirements and muscle depletion. A randomized controlled trial was conducted to test the hypothesis that provision of a late-evening nutritional supplement over a 12-month period would improve body protein stores in patients with cirrhosis. A total of 103 patients (68 male, 35 female; median age 51, range 28-74; Child-Pugh grading: 52A, 31B, 20C) were randomized to receive either daytime (between 0900 and 1900 hours) or nighttime (between 2100 and 0700 hours) supplementary nutrition (710 kcal/day). Primary etiology of liver disease was chronic viral hepatitis (67), alcohol (15), cholestatic (6), and other (15). Total body protein (TBP) was measured by neutron activation analysis at baseline, 3, 6, and 12 months. Total daily energy and protein intakes were assessed at baseline and at 3 months by comprehensive dietary recall. As a percentage of values predicted when well, TBP at baseline was similar for the daytime (85 +/- 2[standard error of the mean]%) and nighttime (84 +/- 2%) groups. For the nighttime group, significant increases in TBP were measured at 3 (0.38 +/- 0.10 kg, P = 0.0004), 6 (0.48 +/- 0.13 kg, P = 0.0007), and 12 months (0.53 +/- 0.17 kg, P = 0.003) compared to baseline. For the daytime group, no significant changes in TBP were seen. Daily energy and protein intakes at 3 months were higher than at baseline in both groups (P < 0.0001), and these changes did not differ between the groups. Provision of a nighttime feed to patients with cirrhosis results in body protein accretion equivalent to about 2 kg of lean tissue sustained over 12 months. This improved nutritional status may have important implications for the clinical course of these patients.

Interventions for sarcopenia and muscle weakness in older people.

three major strategies have been tested for combating the losses in muscle mass and strength that accompany ageing. Those strategies are testosterone replacement for men, growth hormone replacement and resistance exercise training. This review will cover the risks and benefits associated with each of these interventions. searches of PubMed and Web of Science through May 2004 yielded 85 relevant citations for the following descriptors: sarcopenia, aging/ageing, elderly, testosterone, hormone replacement, growth hormone, resistance training, exercise, muscle mass, nutrition and strength. testosterone replacement in elderly hypogonadal men produces only modest increases in muscle mass and strength, which are observed in some studies and not in others. Higher doses have not been given for fear of accelerating prostate cancer. Growth hormone replacement in elderly subjects produces a high incidence of side-effects, does not increase strength and does not augment strength gains resulting from resistance training. Some alternate strategies for stimulating the growth hormone/insulin-like growth factor (IGF) pathway continue to hold promise. The latter include growth hormone releasing hormone (GHRH) and the complex of IGF-I with its major circulating binding protein (IGF-I/IGFBP-3). Resistance training remains the most effective intervention for increasing muscle mass and strength in older people. Elderly people have reduced food intake and increased protein requirements. As a result, adequate nutrition is sometimes a barrier to obtaining full benefits from resistance training in this population.

Effects of protein supplementation of young sheep on resistance development and resilience to parasitic nematodes

The influence of dietary protein content, particularly the supply of metabolisable protein, on immunocompetence and on resilience to pathogenic effects during continuous exposure of young sheep to infective larvae is reviewed for the most important abomasal and small intestinal nematodes infecting young sheep in Australian grazing systems. In lambs infected with Haemonchus contortus supplementary protein improves both development of immunity and resilience in breeds of sheep that are susceptible to haemonchosis, but in relatively resistant breeds dietary supplementation appears unnecessary. Recent studies indicate that the increased protein requirements of Merino weaners parasitised by H. contortus would be met by diets containing about 190 g crude protein/kg dry matter, depending on the rumen degradability of the dietary protein source and level of feed intake. Some evidence exists for an enhanced immune response to Teladorsagia circumcincta in lambs receiving an increased supply of protein at the intestines.Response to protein supplementation of lambs infected with Trichostrongylus colubriformis depends on the metabolisable protein content of the basal diet and on the period of exposure to incoming larvae. Where the basal diet only meets requirements for maintenance or low growth rates, increased supply of rumen undegradable protein enhances immune expression in terms of reducing faecal egg count and expelling adult worms, but does not appear to limit the initial establishment of incoming larvae. Effects on growth rate and wool production are most pronounced during the period of worm expulsion, indicating that this phase of the immune response competes with production when nutrient resources, and particularly protein, are limited.Field trials in the Armidale region have shown that supplementation with protein meals of Merino weaners, exposed to natural infection from pasture, can reduce faecal egg count and improve resilience in terms of both growth rate and wool production. These effects may persist for some time after supplementation ceases. Further work is needed to determine the generality of these responses in other sheep-producing regions and genotypes and to establish cost-effective supplementation strategies.

The metabolic conversion of phenylalanine into tyrosine in the human kidney: Does it have nutritional implications in renal patients?

Recent evidence provided by the in vivo measure of the activity of phenylalanine hydroxylase in humans indicates that the kidney plays a role greater than previously presumed in phenylalanine conversion to tyrosine, an amino acid which has been considered nonessential so far. Homeostasis of tyrosine pools is only partially restored by a reduced uptake of the same amino acid by splanchnic organs in the well-nourished noncatabolic patient with chronic renal failure. Tyrosine pools in uremia can also be restored by an increase in endogenous net protein catabolism, because it occurs during treatment with nonbiocompatible membranes or during acidosis. However, these are trade-offs that are associated with a progressive decrease in muscle mass. Based on these findings, one can argue that with progressively declining renal function and kidney metabolic activity, the nutritional requirements for tyrosine increase progressively. This mechanism could in part account for the increased protein requirements in dialysis-treated end-stage renal disease patients, as compared with predialysis patients. © 2002 by the National Kidney Foundation, Inc.

Nutrition for ill neonates.

1. Danna M. Premer, MD* 2. Michael K. Georgieff, MD* 1. 2. *Department of Pediatrics, Division of Neonatology, University of Minnesota, Minneapolis, MN. After completing this article, readers should be able to: 1. List the factors on which the nutritional needs of the neonate depend. 2. Describe the factors that illnesses alter, thereby changing nutrient requirements. 3. Describe the levels of amino acids that can be initiated without causing intolerance or toxicity in most ill infants. 4. Delineate the adverse effects of protein malnutrition following an acute or prolonged illness or insult. From early in this century, investigators have attempted to determine the optimal nutrient delivery for term infants to promote normal growth and development. In the past 25 years, nutritional investigators have concentrated on the needs of the ideal, healthy preterm infant to try to mimic intrauterine growth and body composition. Although great progress has been made in characterizing the needs of healthy preterm and term infants, the needs of ill, physiologically unstable infants largely have been neglected. The primary reasons for this lack of investigation are the assumption that the needs of ill infants are similar to those of healthy infants and the difficulty of studying metabolic needs in ill infants. The persistent efforts of several groups of investigators and the development of new techniques to study metabolism now have begun to delineate the specific nutritional needs of this particular patient population. Drawing on models generated in the adult surgical intensive care literature of the 1980s makes it possible to try to elucidate the effect of common illnesses and conditions (eg, acute pulmonary disease, bronchopulmonary dysplasia[BPD], congenital heart disease[CHD], sepsis, and surgery) on neonatal metabolism and, therefore, nutritional requirements. The assumption is that changes from the norm in metabolism require alterations in substrate delivery (ie, nutrition). As with adults, it is likely that each illness induces characteristic changes in metabolism. The task for the practitioner is to customize nutritional delivery to fit the specific infant’s …

P.61 Increased protein requirement in patients withliver cirrhosis is due to increased protein degradation

P.61 Increased protein requirement in patients withliver cirrhosis is due to increased protein degradation

The effect of subclinical intestinal nematode infection on the diet selection of growing sheep.

To test the hypothesis that subclinical gastrointestinal parasitism, associated with an impairment in N digestion and metabolism and a reduction in the voluntary feed intake (VFI), could affect the diet selection of sheep given a choice between two feeds that differed in their crude protein (CP) content, twenty-four Texel x Scottish Blackface ewe lambs growing from 28 to 48 kg live weight (LWT) were given a daily dose of 2500 larvae of the intestinal nematode Trichostrongylus colubriformis; twenty-four similar lambs were used as uninfected controls. Six infected and six control lambs were given a free choice between two pelleted feeds (10.4 MJ metabolizable energy/kg), with different CP contents (90 (L) and 214 (H) g CP/kg fresh feed respectively). In addition, eighteen parasitized and eighteen control sheep were given access ad lib. to either feed L, or feed H, or their mixture M (164 g CP/kg; twelve per feed), in order to quantify the effects of the feeds when offered alone, and to test for any interactions between feed CP content and parasitism on the performance of the lambs. Intestinal parasitism reduced significantly (P < 0.001) both the rates of LWT gain (by 30%) and VFI (by 10%). The adult and developing parasitic forms took 4 weeks to establish and develop to a significant adult worm population (as judged by the faecal egg counts and blood variables) and until then there was no effect of parasitism on the performance of the lambs. The diet selection of the lambs given a choice between two feeds was similar between the two groups in the first 4 weeks of the experiment, but differed significantly (P < 0.05) in the second part of the experiment (4th week to the end). Thus, while parasitized lambs had a reduced rate of feed intake, by changing their diet selection they achieved a daily rate of CP intake similar to the control ones. However, since the parasitized lambs had a reduced rate of LWT gain, they also consumed a higher total amount of CP to reach the same LWT. It is concluded that sheep infected daily with a small number of larvae of T. colubriformis and given a choice between two feeds that differ in their protein contents are able to modify their diet selection in order to meet the increased protein requirements resulting from such an infection.

Increased protein requirements in elderly people: new data and retrospective reassessments

Dietary protein requirements of elderly people were determined by short-term nitrogen-balance techniques and using calculations recommended by the 1985 Joint FAO/WHO/UNU Expert Consultation. Twelve men and women aged 56-80 y were randomly assigned to groups that consumed either 0.80 +/- 0.01 or 1.62 +/- 0.02 g protein.kg-1.d-1 (mean +/- SEM). Net nitrogen balance was negative for the lower-protein group (-4.6 +/- 3.4 mg N.kg-1.d-1) and positive for the higher-protein group (13.6 +/- 1.0 mg N.kg-1.d-1); the intake required for nitrogen equilibrium was estimated to be 1.00 g.kg-1.d-1. Nitrogen-balance data from three previous protein requirement studies in elderly people were recalculated by using the same balance formula and combined with the current study data to provide an overall weighted mean protein requirement estimate of 0.91 +/- 0.043 g.kg-1.d-1. Together, the current and retrospective nitrogen-balance data suggest that the mean protein requirement in elderly adults is considerably greater than the 0.60 g.kg-1.d-1 established by the 1985 Joint FAO/WHO/UNU Expert Consultation. A safe protein intake for elderly adults would be 1.0-1.25 g.kg-1.d-1 of high-quality protein.

Calciuria and aminoaciduria in very low birth weight infants fed a high-mineral premature formula with varying levels of protein

To assess the influence of protein intake on renal excretion of calcium and amino acids and on bone mineralization in preterm infants, we randomly selected within weight group strata 27 infants who weighed <1500 gm at birth (nine per group) to be fed a high-mineral (calcium, 940 mg/L; phosphorus, 470 mg/L) premature formula with one of the following protein contents: formula A, 3.0 gm/100 kcal; formula B, 2.7 gm/100 kcal; and formula C, 2.2 gm/100 kcal. Mean (±SD) daily weight gain was greater in infants receiving the higher protein intakes for the first 30 days (formula A, 24.8 ± 5.1 gm; formula B, 20.5 ± 3.8 gm; formula C, 16.2 ± 5.9 gm [analysis of variance: p < 0.01; C < A, p <0.05]). Bone mineral content did not differ at any time point, and all groups had a high prevalence of generalized aminoaciduria (4 weeks: formula A, 56%; formula B, 71%; formula C, 75%). Urinary calcium corrected for creatinine (in milligrams per milligram) increased as protein content decreased (2 weeks: formula A, 0.16 ± 0.10; formula B, 0.20 ± 0.13; formula C, 0.44 ± 0.33 [C > A, C > B, p < 0.05]; 4 weeks: formula A, 0.23 ± 0.15; formula B, 0.34 ± 0.17; formula C, 0.49 ± 0.22 [C > A, p < 0.01]). We conclude that the high mineral content and other components of premature formulas result in a higher growth rate and may increase protein requirements. Failure to meet protein requirements may result in underutilization of absorbed calcium and increased renal excretion of calcium. In preterm infants, higher protein intake probably supports rather than jeopardizes bone mineral accretion, and reduces rather then increases calciuria. (J PEDIATR 1994;125:288-94)

Protein requirement and amino acid imbalance in quail

1. Growing Japanese quail were fed on purified diets based either on dried egg albumen or casein supplemented with methionine. 2. At low protein concentration body mass, N-intake and N-growth requirement of chicks fed on diets containing casein were impaired compared to those fed on diets with egg albumen: in contrast at higher protein concentrations performance was better among those fed on diets with casein. 3. Increased protein requirement was observed among birds fed on diets containing casein compared with those given dried egg albumen. 4. One of the reasons for the increased requirement was attributed to amino acid imbalance in the casein.

Eating, drinking, and cycling. A controlled Tour de France simulation study, Part I.

Sustained exhausting exercise is thought to depress appetite and food intake. The aim of the present investigation was to study the effect of intensive cycling exercise, with an energy expenditure comparable to values derived from the Tour de France, on food and fluid intake, energy balance, nitrogen balance, and nutrient oxidation. Thirteen highly trained cyclists consuming a normal carbohydrate (CHO)-rich diet (60 En%) were studied during a 7-day stay in a respiration chamber. Two preparation days were followed by a standardized resting day (3), after which the subjects completed two exhausting exercise days (4-5). On day 6 the standardized resting day was repeated. Food and fluid intake were measured by weighed procedure. Energy expenditure was calculated from continuous gas analysis. Energy and nitrogen losses were calculated from all measured excretes. The results showed that energy balance (EB) and nitrogen balance (NB) were positive on the first resting day and became negative on the exercise days. EB was positive again on the recovery day whereas NB remained negative. Nitrogen losses almost balanced N intakes (1.7 g.kg-1) indicating an increased protein requirement. CHO oxidation exceeded CHO intake indicating endogenous CHO depletion. Contribution of CHO to energy exchange decreased from 51.4% +/- 3.1% on day 4 to 40.6% +/- 3.4% on day 5; this decrease was compensated by an increased fat oxidation. The food consumption pattern during days 4 and 5 was not different from days 2 and 6. In-between meal consumption accounted for 30.5%-34.3% of total energy intake. Fluid consumption was adequate to compensate for the losses.(ABSTRACT TRUNCATED AT 250 WORDS)

Voluntary Food Intake of Lean and Obese Zucker Rats in Relation to Dietary Energy and Nitrogen Content

Genetically obese (fa/fa) Zucker rats maintain a normal lean body size but deposit excessive amounts of body fat. Preferential use of substrates for lipid synthesis results in inefficient use of dietary nitrogen for protein deposition. Three studies were carried out to determine whether an increased protein requirement caused hyperphagia and whether young Zucker rats preferentially regulated protein or energy intake. Rats were offered isoenergetic diets with nitrogen contents ranging from 4.5 to 53.2 mg/g, or isonitrogenous diets with energy contents of 2.2, 3.3 or 4.2 kcal/g. In both situations obese rats had significantly higher food intakes than lean rats. Within phenotype the rats maintained an almost constant energy intake so that nitrogen intake was proportional to dietary nitrogen concentration. In a third experiment lean and obese rats were given different proportions of their control protein intake by stomach tube. Energy intake was determined by voluntary consumption of a protein-free diet. Within phenotype energy intake was the same for all levels of protein intake. It appears that obese Zucker rats regulate energy intake at an elevated level and that protein intake is determined by dietary nitrogen content. Hyperphagia does not appear to result from a desire to obtain protein.

Age and sex differences in the diet and feeding strategies of the green monkey, Cercopithecus sabaeus

The diet and activity patterns of a group of green monkeys ( Cercopithecus sabaeus) living in the Parc National du Niokolo-Koba, Senegal, were studied over a complete annual cycle, and some important age and sex differences were found. In the annual diet, no clear age-sex differences emerged for feeding on fruit, invertebrates, or ‘other’ (mainly foliage) foods, but adult males ate more flowers. In the annual time-budget, no sex differences were found among immature monkeys, but adult females spent less time feeding than adult males. This difference is accounted for by the greater ‘metabolic body-size’ of adult males. There were seasonal differences amongst the adults: males spent more time feeding than females in the dry season, but not in the wet season. Males ate more fruit and flowers in the dry season, while females ate more foliage in the wet season. Lactating females fed less than nonlactating females. The differences between adults are attributed to superior competitive ability by males over ‘first choice’ foods (fruit and flowers), and to alternative energetic and nutritional strategies of lactating females in response to increased protein requirements.

BLOOD LEVELS OF CRITICAL AMINO ACIDS IN VERY LOW BIRTHWEIGHT INFANTS ON A HIGH HUMAN MILK PROTEIN INTAKE

A method for a semi-industrial production of human milk subfractions (human milk protein and human milk fat isolates) is described. Four very low birthweight (VLBW) newborn were given a human milk protein isolate added to the mother's own fresh expressed milk in addition to sodium chloride up to 20 mEkv/liter. Growth followed the intrauterine growth curve. Urea levels did not increase in spite of providing a double-normal protein intake. There was no metabolic acidosis and the blood levels of free amino acids determined with a micro-method did not exceed those seen after a normal meal. The concentrated human milk protein product showed a considerable specific sIgA activity against E. coli 0-antigen. It seems possible to use similar "lacto-engineering"-techniques in order to satisfy the increased protein requirements of the VLBW infant, while providing the caloric requirements, without causing any visible disturbance of blood-homeostasis of urea, amino acids or base excess. The method could provide knowledge about the "human milk protein requirements" and a controlled study has been started.

Protein deficiency and energy restriction in young cebus monkeys.

Infant cebus monkeys (Cebus albifrons) were fed liquid formulas that were limited in protein, energy, or a combination of the two restrictions. Weight gain, food intake, hematological development, and plasma protein and cholesterol levels were monitored over a 20-week period. The animals restricted in protein developed the classical signs of protein deficiency--reductions in plasma albumin, a mild anemia, accumulation of fat in the liver, and, in a few cases, facial edema. These animals maintained a relatively high energy intake, and apparently wasted energy when compared to similarly non-growing energy-restricted animals. Energy-restricted animals did not exhibit these symptoms, even when their daily protein intake was reduced to match that of protein-restricted monkeys. It is concluded that an energy restriction superimposed upon a limited protein intake did not increase protein requirements or precipitate protein deficiency.

The Influence of Sybean Antitrypsin on the Intestinal Proteolysis of the Chick

The influence of a raw-soybean diet on the chicks’ intestinal proteolysis was studied, in order to explain the growth-retarding effect. In chicks up to three weeks old, intestinal proteolysis was almost completely inhibited. From the 4th week proteolysis increased, approaching the normal at 6 weeks. The presence or absence of antitryptic activity was closely correlated with depressed or normal proteolytic activity. Hypertrophy of the pancreas developed in the raw soybean group, probably because of increased enzyme production to overcome the inhibitor. The chick growth retardation by antitrypsin can be explained by the unavailability of protein especially in the first three weeks of age and an increased protein requirement by stimulated pancreas.