-
Journal of the American Society of... May 1993Protein intake has been recognized as a modulator of renal function for over half a century. This review analyzes the renal response induced by changes in habitual... (Review)
Review
Protein intake has been recognized as a modulator of renal function for over half a century. This review analyzes the renal response induced by changes in habitual protein intake and with acute amino acid infusion or a meat meal in humans and animals. The pattern and magnitude of changes in GFR and creatinine clearance are examined along with a discussion of the effect of the variability of these measurements among individuals and populations on the interpretation of clinical studies. Potential mechanisms of protein-induced changes in GFR and creatinine clearance are examined, including changes in the hormonal milieu, glomerular hemodynamics, and other intrarenal processes. Habitual dietary protein consumption varies significantly with respect to age, gender, and lean body mass--factors that are well known to influence GFR. This correlation raises the possibility that (1) variation in dietary protein intake may account, at least in part, for the differences in renal function among individuals; and (2) the level of protein intake should be assessed in defining the normal range of renal function.
Topics: Creatinine; Dietary Proteins; Glomerular Filtration Rate; Humans; Kidney; Reference Values
PubMed: 8329667
DOI: 10.1681/ASN.V3111723 -
Journal of Special Operations Medicine... 2015Military recommendations for dietary protein are based on the recommended dietary allowance (RDA) of 0.8 g of protein per kilogram of body mass (BM) established by the... (Review)
Review
Military recommendations for dietary protein are based on the recommended dietary allowance (RDA) of 0.8 g of protein per kilogram of body mass (BM) established by the Food and Nutrition Board, Institute of Medicine (IOM) of the National Academies. The RDA is likely adequate for most military personnel, particularly when activity levels are low and energy intake is sufficient to maintain a healthy body weight. However, military recommendations account for periods of increased metabolic demand during training and real-world operations, especially those that produce an energy deficit. Under those conditions, protein requirements are higher (1.5-2.0 g/kg BM) in an attempt to attenuate the unavoidable loss of muscle mass that occurs during prolonged or repeated exposure to energy deficits. Whole foods are recommended as the primary method to consume more protein, although there are likely operational scenarios where whole foods are not available and consuming supplemental protein at effective, not excessive, doses (20-25 g or 0.25-0.3 g/kg BM per meal) is recommended. Despite these evidence-based, condition-specific recommendations, the necessity of protein supplements and the requirements and rationale for consuming higher-protein diets are often misunderstood, resulting in an overconsumption of dietary protein and unsubstantiated health-related concerns. This review will provide the basis of the US military dietary protein requirements and highlight common misconceptions associated with the amount and safety of protein in military diets.
Topics: Dietary Proteins; Dietary Supplements; Humans; Military Personnel; Nutritional Requirements; Organizational Policy; Recommended Dietary Allowances; United States; United States Department of Defense
PubMed: 26630101
DOI: 10.55460/J1H4-1EYT -
Comparative Biochemistry and... Dec 2003Mammals are ureotelic and respond to an increased protein intake with an increase in glomerular filtration rate and renal plasma flow. Birds and terrestrial insects are... (Review)
Review
Mammals are ureotelic and respond to an increased protein intake with an increase in glomerular filtration rate and renal plasma flow. Birds and terrestrial insects are uricotelic and following a high protein intake increase tubular urate secretion by the kidney (birds) or Malpighian tubule (insects). Ureogenic fish given NH(4)Cl increase gill and renal clearance of urea and gill clearance of ammonia. Renal mass increases in mammals, birds and reptiles given a high protein intake. Thus, animals in general respond to an increase in protein intake with a change in excretory function such as to increase the clearance of the major nitrogenous end-products of protein metabolism. The components of this general animal excretory response include; a redistribution of regional perfusion with increased renal and gill blood flow, increased GFR and gill ammonia clearance, increased renal tubular urate clearance, changes in urea transport protein abundance and/or function and renal hypertrophy. Animal groups differ as to which components are accentuated. Amino acid catabolism with generation of ammonia appears to be a necessary prerequisite for this excretory response to occur. A hypothesis is put forward that ammonia itself is a regulatory molecule and an important signal communicating between amino acid catabolism following an increase in protein intake and the sequence of events leading to a change in excretory function.
Topics: Animals; Dietary Proteins; Glomerular Filtration Rate; Kidney; Models, Biological; Renal Plasma Flow; Species Specificity
PubMed: 14662303
DOI: 10.1016/j.cbpc.2003.08.012 -
Blood Purification 2021Over the last 2 decades, there has been a great accumulation of new evidence regarding the management of nutritional and metabolic aspects of kidney disease. The 2020... (Review)
Review
Over the last 2 decades, there has been a great accumulation of new evidence regarding the management of nutritional and metabolic aspects of kidney disease. The 2020 update to the KDOQI Clinical Practice Guideline for Nutrition in CKD provides a comprehensive up-to-date information on the understanding and care of patients with CKD. It provides updated information on nutritional aspects of kidney disease for the practicing clinician and allied health-care workers. The current manuscript provides an overview of the updated guideline statements on major subjects including nutritional assessment, dietary protein and energy intake, nutritional supplementation, micronutrients, and electrolytes. The guidelines are focused on dietary management rather than all possible nutritional interventions.
Topics: Dietary Proteins; Dietary Supplements; Energy Intake; Humans; Micronutrients; Nutrition Assessment; Nutritional Status; Renal Insufficiency, Chronic
PubMed: 33652433
DOI: 10.1159/000513698 -
Nutrition Reviews Nov 1998A recent randomized, double-blind, placebo-controlled trial found that protein supplementation improved recovery from femoral fractures in an elderly population. A... (Review)
Review
A recent randomized, double-blind, placebo-controlled trial found that protein supplementation improved recovery from femoral fractures in an elderly population. A 6-month course of protein supplementation (20 g/day, 5 days/week) improved serum prealbumin and insulin-like growth factor I (IGF-I) concentrations, minimized bone loss, and decreased length of stay in rehabilitation facilities.
Topics: Aged; Dietary Proteins; Dietary Supplements; Female; Femoral Fractures; Humans; Male; Nutrition Policy; Nutritional Requirements; Randomized Controlled Trials as Topic
PubMed: 9838800
DOI: 10.1111/j.1753-4887.1998.tb01672.x -
Nutrition Reviews Feb 2008Inclusion of dietary protein in meals and beverages affects the hepatic synthesis of the protein albumin. Besides dietary protein, several factors can influence albumin... (Review)
Review
Inclusion of dietary protein in meals and beverages affects the hepatic synthesis of the protein albumin. Besides dietary protein, several factors can influence albumin metabolism and affect plasma albumin. The role of aging in albumin synthesis is unclear. Recent research documents that albumin synthesis rate is influenced comparably in younger and older adults by dietary protein ingestion and changes in dietary protein quantity. This emphasizes the importance for all adults to consume an adequate amount of dietary protein.
Topics: Adult; Aged; Aging; Albumins; Diet; Dietary Proteins; Energy Metabolism; Female; Humans; Male
PubMed: 18254875
DOI: 10.1111/j.1753-4887.2007.00012.x -
European Journal of Clinical Nutrition Apr 1999Studies of the effects of dietary protein level on human metabolism have usually concentrated on the effects of protein deprivation and on establishing a minimum dietary... (Review)
Review
Studies of the effects of dietary protein level on human metabolism have usually concentrated on the effects of protein deprivation and on establishing a minimum dietary requirement. By contrast, less is known about the effects of very high protein diets, although general levels of protein intake in the developed world are increasing, and high protein diets have been advocated for maintaining or increasing muscle mass in certain groups of the population. This article, therefore, examines the response of protein metabolism to high dietary protein, studied in adults by nitrogen balance and isotopic tracer techniques, and concentrating on the evidence for increased lean body mass. It is concluded that high protein feeding initially results in protein retention, with greater cycling of body protein in response to meals, but that neither N-balance nor isotopic tracer methods possess sufficient sensitivity to detect whether a long term increase in functional lean tissue ensues. Improved methods of body composition measurement will be needed to establish this. Moreover, the absence of strong evidence that high protein diets confer any advantage in terms of strength or health must be weighed against potentially injurious consequences.
Topics: Adaptation, Physiological; Adult; Amino Acids; Body Composition; Body Constitution; Dietary Proteins; Energy Intake; Energy Metabolism; Humans; Leucine; Nitrogen; Nutrition Assessment; Oxidation-Reduction; Proteins; Radioisotopes; Sensitivity and Specificity
PubMed: 10365979
DOI: 10.1038/sj.ejcn.1600742 -
Current Opinion in Critical Care Aug 2022Critically ill patients experience skeletal muscle wasting that may contribute to the profound functional deficits in those that survive the initial injury. Augmented... (Review)
Review
PURPOSE OF REVIEW
Critically ill patients experience skeletal muscle wasting that may contribute to the profound functional deficits in those that survive the initial injury. Augmented protein delivery has the potential to attenuate muscle loss, yet the ability for dietary protein to improve patient outcomes is reliant on effective protein metabolism. This review will discuss the recent literature on protein delivery and digestion, amino acid absorption, and muscle protein synthesis (MPS) in critically ill adults.
RECENT FINDINGS
Critically ill patients are prescribed protein doses similar to international recommendations, yet actual delivery remains inadequate. The majority of trials that have achieved higher protein doses have observed no effect on muscle mass, strength or function. Critically ill patients have been observed to have minimal deficits in protein digestion and amino acid absorption when delivery bypasses the stomach, yet postprandial MPS is impaired. However, the literature is limited due to the complexities in the direct measurement of protein handling.
SUMMARY
Postprandial MPS is impaired in critically ill patients and may exacerbate muscle wasting experienced by these patients. Studies in critically ill patients require assessment not only of protein delivery, but also utilization prior to implementation of augmented protein doses.
Topics: Adult; Amino Acids; Critical Illness; Dietary Proteins; Humans; Muscle Proteins; Muscle, Skeletal; Muscular Atrophy
PubMed: 35792908
DOI: 10.1097/MCC.0000000000000959 -
Current Opinion in Clinical Nutrition... Nov 2009Protein requirement in healthy young and old individuals is traditionally defined as the lowest protein intake sufficient to achieve neutral body protein balance. This... (Review)
Review
PURPOSE OF REVIEW
Protein requirement in healthy young and old individuals is traditionally defined as the lowest protein intake sufficient to achieve neutral body protein balance. This concept, however, cannot be applied to those conditions characterized by unavoidable protein catabolism despite optimal nutrition, such as inactivity and diseases associated with systemic inflammation.
RECENT FINDINGS
The ability of dietary proteins to promote protein anabolism is reduced by inactivity and inflammatory mediators, whereas physical exercise ameliorates the efficiency in using dietary proteins. Consequently, the protein intake level associated with the lowest rate of catabolism in inactivity and/or inflammation is greater than the minimum protein intake required to achieve neutral protein balance in healthy, physically active individuals. A protein intake of 1.2 g.kg.day is currently recommended for inactive healthy individuals, whereas guidelines recommend up to 1.5 g.kg.day in patients with severe systemic inflammation, such as those affected by critical illness or cancer. High protein intake accelerates progression of renal insufficiency but does not affect renal function in healthy individuals.
SUMMARY
In inflammation and/or inactivity a relatively high protein intake may be required to promote synthesis of specific proteins, prevent depletion of selected amino acids (e.g., glutamine or arginine), modulate immune functions, counteract insulin resistance and redox unbalance. Thus, an optimal protein/amino acid intake may be greater than that required to decrease whole body protein wasting.
Topics: Amino Acids; Diet; Dietary Proteins; Exercise; Humans; Immune System; Inflammation; Insulin Resistance; Motor Activity; Nutritional Requirements; Oxidation-Reduction; Proteins; Sedentary Behavior
PubMed: 19741515
DOI: 10.1097/MCO.0b013e32833193bd -
The American Journal of Clinical... Jul 2015
Topics: Dietary Proteins; Female; Humans; Kidney; Male; Maternal Nutritional Physiological Phenomena; Pregnancy; Pregnancy Trimester, First
PubMed: 26063690
DOI: 10.3945/ajcn.115.112672