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The Physician and Sportsmedicine Jun 2009Dietary protein is required to promote growth, repair damaged cells and tissue, synthesize hormones, and for a variety of metabolic activities. There are multiple... (Review)
Review
Dietary protein is required to promote growth, repair damaged cells and tissue, synthesize hormones, and for a variety of metabolic activities. There are multiple sources of proteins available; however, animal sources of protein contain all essential amino acids and are considered complete sources of protein, whereas plant proteins lack some of the essential amino acids and are therefore classified as incomplete. There is a significant body of evidence to indicate that individuals who are engaged in intense training require more dietary protein than sedentary counterparts (ie, 1.4-2 g/kg/day). For most individuals, this level of protein intake can be obtained from a regular and varied diet. However, recent evidence indicates that ingesting protein and/or amino acids prior to, during, and/or following exercise can enhance recovery, immune function, and growth and maintenance of lean body mass. Consequently, protein and amino acid supplements can serve as a convenient way to ensure a timely and/or adequate intake for athletes. Finally, adequate intake and appropriate timing of protein ingestion has been shown to be beneficial in multiple exercise modes, including endurance, anaerobic, and strength exercise.
Topics: Amino Acids; Body Composition; Dietary Proteins; Exercise; Humans; Nutritional Requirements; Physical Endurance; Sports
PubMed: 20048505
DOI: 10.3810/psm.2009.06.1705 -
Nutrition in Clinical Care : An... 2002Exercise and physical activity increase energy expenditure up to 10-fold. This brief review will focus on the effect of exercise on protein requirements. Evidence has... (Review)
Review
Exercise and physical activity increase energy expenditure up to 10-fold. This brief review will focus on the effect of exercise on protein requirements. Evidence has accumulated that amino acids are oxidized as substrates during prolonged submaximal exercise. In addition, studies have determined that both endurance and resistance training exercise increase skeletal muscle protein synthesis and breakdown in the post-exercise recovery period. Studies using nitrogen balance have further confirmed that protein requirements for individuals engaged in regular exercise are increased. The current recommended intakes of protein for strength and endurance athletes are 1.6 to 1.7 g/kg and 1.2 to 1.4 g/kg per day, respectively. Presently, most athletes consume an adequate amount of protein in their diet. The timing and nutritional content of the post-exercise meal, although often overlooked, are known to have synergistic effects on protein accretion after exercise. New evidence suggests that individuals engaging in strenuous activity consume a meal rich in amino acids and carbohydrate soon after the exercise bout or training session.
Topics: Dietary Proteins; Energy Metabolism; Exercise; Homeostasis; Humans; Muscle Proteins; Nutritional Requirements
PubMed: 12380246
DOI: 10.1046/j.1523-5408.2002.00606.x -
International Journal For Vitamin and... Mar 2011Dietary proteins influence body weight by affecting four targets for body weight regulation: satiety, thermogenesis, energy efficiency, and body composition. Protein... (Review)
Review
Dietary proteins influence body weight by affecting four targets for body weight regulation: satiety, thermogenesis, energy efficiency, and body composition. Protein ingestion results in higher ratings of satiety than equicaloric amounts of carbohydrates or fat. Their effect on satiety is mainly due to oxidation of amino acids fed in excess; this effect is higher with ingestion of specific "incomplete" proteins (vegetal) than with animal proteins. Diet-induced thermogenesis is higher for proteins than for other macronutrients. The increase in energy expenditure is caused by protein and urea synthesis and by gluconeogenesis. This effect is higher with animal proteins containing larger amounts of essential amino acids than with vegetable proteins. Specifically, diet-induced thermogenesis increases after protein ingestion by 20 - 30 %, but by only 5 - 10 % after carbohydrates and 0 - 5 % after ingestion of fat. Consumption of higher amounts of protein during dietary treatment of obesity resulted in greater weight loss than with lower amounts of protein in dietary studies lasting up to one year. During weight loss and decreased caloric intake, a relatively increased protein content of the diet maintained fat-free mass (i. e. muscle mass) and increased calcium balance, resulting in preservation of bone mineral content. This is of particular importance during weight loss after bariatric surgery because these patients are at risk for protein malnutrition. Adequate dietary protein intake in diabetes type 2 is of specific importance since proteins are relatively neutral with regard to glucose and lipid metabolism, and they preserve muscle and bone mass, which may be decreased in subjects with poorly controlled diabetes. Ingestion of dietary proteins in diabetes type 1 exerts a delayed postprandial increase in blood glucose levels due to protein-induced stimulation of pancreatic glucagon secretion. Higher than minimal amounts of protein in the diet needed for nitrogen balance may play an important role for the increasing number of elderly obese subjects in our industrialized societies, since proteins exert beneficial effects in the conditions of overweight, metabolic syndrome, cardiovascular risk factors, bone health, and sarcopenia. Adverse effects of increased dietary proteins have been observed in subjects with renal impairment- this problem is frequently observed in the elderly, hypertensive, and diabetic population. Nevertheless, dietary proteins deserve more attention than they have received in the past.
Topics: Body Composition; Body Weight; Diabetes Mellitus; Diet, Reducing; Dietary Proteins; Energy Metabolism; Health Promotion; Humans; Insulin Resistance; Nutrition Policy; Obesity; Proteins; Satiety Response; Thermogenesis
PubMed: 22139563
DOI: 10.1024/0300-9831/a000059 -
The American Journal of Clinical... Dec 2009
Topics: Bone Density; Dietary Proteins; Humans
PubMed: 19864406
DOI: 10.3945/ajcn.2009.28812 -
Advances in Food and Nutrition Research 2020Proteins and its building blocks, amino acids, have many physiological roles in the body. While some amino acids can be synthesized endogenously, exogenous protein and... (Review)
Review
Proteins and its building blocks, amino acids, have many physiological roles in the body. While some amino acids can be synthesized endogenously, exogenous protein and amino acids are necessary to maintain homeostasis. Because skeletal muscle contains a large portion of endogenous protein and plays important roles in movement, regulation, and metabolism, imbalanced protein and amino acid availability may result in clinical conditions including skeletal muscle atrophy, impaired muscle growth or regrowth, and functional decline. Aging is associated with changes in protein metabolism and multiple physiological and functional alterations in the skeletal muscle that are accentuated by decreased dietary protein intake and impaired anabolic responses to stimuli. Inactivity and chronically elevated inflammation of the skeletal muscle can initiate and/or augment pathological remodeling of the tissue (i.e., increase of fat and fibrotic tissues and atrophy of the muscle). Defining an adequate amount of dietary protein that is appropriate to maintain the availability of amino acids for biological needs is necessary but is still widely debated for older adults. This chapter will provide (i) an overview of dietary protein and amino acids and their role in skeletal muscle health; (ii) an overview of skeletal muscle structure and function and the deterioration of muscle that occurs with advancing age; (iii) a discussion of the relationship between protein/amino acid metabolism and skeletal muscle decline with aging; and (iv) a brief discussion of optimal protein intakes for older adults to maintain skeletal muscle health in aging.
Topics: Aging; Amino Acids; Dietary Proteins; Humans; Muscle, Skeletal; Muscular Diseases
PubMed: 32035599
DOI: 10.1016/bs.afnr.2019.08.002 -
Fish & Shellfish Immunology Nov 2020A 120-day feeding trial was conducted to investigate the effects of relative higher and lower dietary protein levels on the growth, immunity and anti-stress of abalone...
A 120-day feeding trial was conducted to investigate the effects of relative higher and lower dietary protein levels on the growth, immunity and anti-stress of abalone Haliotis discus hannai fed diets with 17.64% (low), 30.49% (normal) and 43.27% (high) of proteins, respectively. The results showed that compared with 30.49% of dietary protein, 17.64% and 43.27% of dietary protein levels significantly decreased the weight gain rate and the activities of α-amylase, trypsin, alanine aminotransferase and aspartate aminotransferase in the hepatopancreas and serum of abalone (P < 0.05). Abalone fed 30.49% of dietary protein had the highest activity of superoxidase, acid phosphatase, alkaline phosphatase, lysozyme and the total anti-oxidative capacity, and the lowest content of malondialdehyde in the serum and hepatopancreas (P < 0.05). The gene expressions of TOR, S6k, Bcl-2, IκB, NfκB, TNF-α and Nrf were significantly up-regulated in the group with 30.49% of dietary protein (P < 0.05). Pathological abnormalities in hepatocyte cells of abalone were found in the groups with 17.64% and 43.27% of dietary protein. Meanwhile, accumulative mortalities of abalone after the Vibrio parahaemolyticus challenge test and heat stress test were significantly increased within these two groups (P < 0.05). In conclusion, the excessive (43.27) or deficient (17.64) dietary protein levels depressed the growth and immunity of abalone. Combined with the stress tests results, 17.63% or 43.27% of dietary protein contents are not recommended to the abalone facing the stress of vibriosis or high-water temperature (≥28 °C).
Topics: Animal Feed; Animal Husbandry; Animals; Diet; Dietary Proteins; Gastropoda; Gene Expression Regulation; Immunity, Innate; Signal Transduction; TOR Serine-Threonine Kinases; Vibrio parahaemolyticus
PubMed: 32781210
DOI: 10.1016/j.fsi.2020.08.004 -
Nutrition Research (New York, N.Y.) Aug 2013Lean body mass (LBM) is important to maintain physical function during aging. We hypothesized that dietary protein intake and leisure-time physical activity are...
Lean body mass (LBM) is important to maintain physical function during aging. We hypothesized that dietary protein intake and leisure-time physical activity are associated with LBM in community-dwelling older adults. To test the hypothesis, participants (n = 237; age, 65-92 years) did 3-day weighed food records and reported physical activity. Body composition was assessed using dual-energy x-ray absorptiometry. Protein intake was 0.98 ± 0.28 and 0.95 ± 0.29 g/kg body weight in male and female participants, respectively. Protein intake (in grams per kilogram of body weight) was associated with LBM (in kilograms); that is, the differences in LBM were 2.3 kg (P < .05) and 2.0 kg (P = .054) between the fourth vs the first and the fourth vs the second quartiles of protein intake, respectively. Only a minor part of this association was explained by increased energy intake, which follows an increased protein intake. Our study shows that dietary protein intake was positively associated with LBM in older adults with a mean protein intake higher than the current recommended daily allowance of 0.8 g/kg per day. Leisure-time physical activity, predominantly consisting of endurance type exercises, was not related to LBM in this group.
Topics: Absorptiometry, Photon; Aged; Aging; Body Composition; Body Fluid Compartments; Diet; Diet Records; Dietary Proteins; Energy Intake; Exercise; Female; Humans; Male; Recommended Dietary Allowances; Residence Characteristics; Sex Factors
PubMed: 23890349
DOI: 10.1016/j.nutres.2013.05.014 -
The Journal of Nutrition Mar 1995The first purely nutritional investigation into experimental atherosclerosis was carried out by Ignatowski in 1908. Believing that a toxic metabolite of animal protein...
The first purely nutritional investigation into experimental atherosclerosis was carried out by Ignatowski in 1908. Believing that a toxic metabolite of animal protein led to atherosclerosis, he fed meat to adult rabbits and milk and egg yolk to weanling rabbits and caused atherosclerosis. For the next two decades experimental efforts from many laboratories were directed at determining which, if any, animal protein was the most atherogenic. The discovery in 1912 that dietary cholesterol per se was atherogenic turned attention to fat and cholesterol, eclipsing work on dietary protein. In 1926 Clarkson and Newburgh showed that the amount of cholesterol present in the animal protein they fed was insufficient to be atherogenic, demonstrating that some factor other than lipid determined atherogenicity. In 1940 Meeker and Kesten showed that animal protein (casein) was more atherogenic that plant protein (soy). Carroll and his co-workers showed that most proteins of animal origin were more cholesterolemic for rabbits than were proteins of vegetable origin, although there was some overlap. Cholesterol turnover is slower and fecal excretion of cholesterol is reduced in rabbits fed casein as opposed to those fed soy protein. The mechanisms underlying this effect are moot.
Topics: Animals; Arteriosclerosis; Cholesterol, Dietary; Dietary Proteins; Dietetics; History, 20th Century; Rabbits
PubMed: 7884538
DOI: 10.1093/jn/125.suppl_3.589S -
Nutrition (Burbank, Los Angeles County,... 2014With aging, kidney function declines, as evidenced by reduced glomerular filtration rate. It is controversial whether or not high protein intake accelerates this...
OBJECTIVE
With aging, kidney function declines, as evidenced by reduced glomerular filtration rate. It is controversial whether or not high protein intake accelerates this decline. The aim of this study was to determine whether high protein intake was associated with declines in kidney function among older patients.
METHODS
We examined whether dietary protein is associated with change in kidney function (mean follow-up 6.4 y [SD = 1.4, range = 2.5-7.9] in the Cardiovascular Health Study (N = 3623). We estimated protein intake using a food frequency questionnaire and estimated glomerular filtration rate from cystatin C. Associations between protein intake and kidney function were determined by linear and logistic regression models.
RESULTS
Average protein intake was 19% of energy intake (SD = 5%). Twenty-seven percent (n = 963) of study participants had rapid decline in kidney function, as defined by (ΔeGFRcysC > 3 mL•min•1.73 m(2)). Protein intake (characterized as g/d and % energy/d), was not associated with change in estimated glomerular filtration rate (P > 0.05 for all comparisons). There were also no significant associations when protein intake was separated by source (animal and vegetable).
CONCLUSION
These data suggest that higher protein intake does not have a major effect on kidney function decline among elderly men and women.
Topics: Aged; Aging; Diet; Dietary Proteins; Feeding Behavior; Female; Glomerular Filtration Rate; Health; Humans; Kidney; Male; Regression Analysis; Surveys and Questionnaires
PubMed: 24984995
DOI: 10.1016/j.nut.2013.12.006 -
The Journal of Nutrition Apr 2000
Review
Topics: Adult; Body Composition; Dietary Proteins; Humans; Metabolism; Physical Fitness
PubMed: 10736347
DOI: 10.1093/jn/130.4.886