Effects Of Dietary Protein Intake Research Articles

Dietary Protein Intake Is Not Associated with Progression of Diabetic Nephropathy in Patients without Macroalbuminuria

Background/Aims: Diabetic nephropathy is an important problem in patients with diabetes. However, little is known about the effect of dietary protein intake on albuminuria in patients with diabetes. Thus, the aim of this study was to clarify the association between dietary protein intake and change in urinary albumin excretion (UAE) or estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes. Methods: In this retrospective cohort study, we included 143 patients (71 men, average 64.0 (10.5) years, and median 14.5 (6.7-38.5) mg/gCr) without macroalbuminuria (UAE over 300 mg/gCr). Change in UAE or eGFR was defined as increase of UAE or GFR/follow-up duration (year). Habitual protein intake was estimated by a self-administered diet history questionnaire. Results: Median follow-up duration was 5 years. Logistic regression analyses showed that baseline UAE was associated with change in UAE (β = 0.217, p = 0.012), but the protein intake was not (β = -0.064, p = 0.454) (Table). In addition, baseline Cr was associated with change in eGFR (β = 0.344, p = 0.001), but the protein intake was not (β = 0.001, p = 0.988). Conclusions: Dietary protein intake was not associated with change in UAE or eGFR. This result suggests that protein restriction is not necessary in patients without macroalbuminuria. Multiple regression analysis on δUAE or δeGFRδUAEstandardized regression coefficientp valueδeGFRstandardized regression coefficientp valueLog (UAE+1)0.2170.012Log (UAE+1)0.0490.560Protein intake (g/kg/day)-0.0640.454Protein intake (g/kg/day)-0.0330.698Usage of RAS inhibitor0.1140.193Usage of RAS inhibitor-0.2020.021Creatinine0.0470.646Creatinine0.398<0.001Age-0.0030.977Age0.0610.490BMI0.1190.184BMI-0.0420.634Men-0.1430.163Men0.1210.237 Disclosure A. Kaji: None. Y. Hashimoto: Research Support; Self; Asahi Kasei Corporation, Fuji Foundation for Protein Research, Japan Society for the Promotion of Science, MSD K.K.. R. Sakai: None. T. Okamura: None. M. Yamazaki: None. M. Fukui: Research Support; Self; Grant-in-Aid for Scientific Research (C), Ono Pharmaceutical Co., Ltd., AstraZeneca, Astellas Pharma US, Inc., Daiichi Sankyo Company, Limited, Eli Lilly and Company, Kyowa Hakko Kirin Co., Ltd., Kissei Pharmaceutical Co., Ltd., MSD K.K., Novo Nordisk Foundation.

Dietary protein intake in school-age children and detailed measures of body composition: the Generation R Study.

A high-protein diet in infancy increases the risk of obesity, but the effects of dietary protein intake in mid-childhood on body composition are unclear. Therefore, we studied associations of protein intake (total, animal and plant-sourced) at 8 years of age with anthropometric measures and body composition up to age 10 years. We included 3991 children of the Generation R Study, a prospective cohort in the Netherlands. Dietary protein intake was assessed at 8 years of age using a food-frequency questionnaire and is expressed in energy percentage (E%). Anthropometric measures and body composition (using dual-energy X-ray absorptiometry (DXA)) were assessed at 6 years and during follow-up at 10 years. We calculated body mass index (BMI), fat mass index (FMI), and fat-free mass index (FFMI). All outcomes were sex- and age-standardized and overweight (yes/no) was derived from BMI-SDS. We examined associations of protein intake at 8 years with the combined risk of overweight and obesity, and body composition at 10 years using multivariable logistic and linear regression models. These analyses were adjusted for outcomes at 6 years and protein intake in early life. In multivariable-adjusted models, a 5E% higher protein intake at 8 years was associated with a higher combined risk of overweight and obesity up to 10 years (odds ratio (OR) 1.51, 95% confidence interval (CI): 1.22,1.86), independent of whether it replaced carbohydrates or fat. However, this was mainly explained by an association of protein intake with a higher FFMI (0.07 standard deviation scores (SDS) per 5E%, 95% CI: 0.02,0.11), not FMI. Both plant and animal were associated with a higher FFMI, but the association was stronger for protein from plant sources. For FMI, our findings also suggest trends of higher plant protein intake with lower FMI, and higher animal protein intake with higher FMI. Following this, a higher plant protein intake at the expense of animal protein was associated with a lower FMI (-0.08 SDS per 5E%, 95% CI: -0.15,-0.01). We observed that a higher protein intake in mid-childhood is associated with a higher fat-free mass. Our findings also suggest that protein from plant sources seems to be beneficial for body composition in school-age children.

The effect of dietary protein intake on immune status in pigs of different genotypes

ABSTRACT Little is known about the immune status of different pig breeds and the role of dietary protein intake. The present study, performed on 96 barrows (48 pure-bred Bama mini-pigs (fatty genotype) and 48 Landrace pigs (lean genotype)) randomly assigned to two dietary treatment groups (low- or adequate protein diet), with twenty-four24 individuals per treatment), evaluated the levels of immunoglobulins and cytokines in serum, and intestinal and splenic innate immunity on the two breeds. Data showed significant interactions between breed and diet for adaptive and innate immunity. Throughout the experiment, Landrace pigs showed significantly higher intestinal immune responses than Bama mini-pigs, and an adequate provision of dietary protein improved the expression of specific antibodies in early growth phases. These finding have important implication for improving the immune status of Landrace pigs, which are a major source of protein for humans. Abbreviations: BW: Body Weight; NRC diet: National Research Council diet; GB diet: Chinese conventional diet; CSFV: Classical Swine Fever Virus; IgG: Immunoglobulin G; IgM: Immunoglobulin M; SIgA: Secretory Immunoglobulin A.

The effects of dietary protein intake on appendicular lean mass and muscle function in elderly men: a 10-wk randomized controlled trial

Background: The Recommended Daily Allowance (RDA) for protein intake in the adult population is widely promoted as 0.8 g · kg-1 · d-1 Aging may increase protein requirements, particularly to maintain muscle mass.Objective: We investigated whether controlled protein consumption at the current RDA or twice the RDA (2RDA) affects skeletal muscle mass and physical function in elderly men.Design: In this parallel-group randomized trial, 29 men aged >70 y [mean ± SD body mass index (in kg/m2): 28.3 ± 4.2] were provided with a complete diet containing either 0.8 (RDA) or 1.6 (2RDA) g protein · kg-1 · d-1, aimed to balance energy needs. Before treatment and after 10 wk of intervention, whole-body and appendicular lean mass were measured by using dual-energy X-ray absorptiometry. Knee-extension peak power was measured with dynamometry.Results: Both groups were found to have been in a moderate negative energy balance (mean ± SD RDA: 209 ± 213 kcal/d; 2RDA 145 ± 214 kcal/d; P= 0.427 for difference between the groups). In comparison with RDA, whole-body lean mass increased in 2RDA (P = 0.001; 1.49 ± 1.30 kg, P < 0.001 compared with -0.55 ± 1.49 kg, P = 0.149). This difference was mostly accounted for by an increase in trunk lean mass found in 2RDA (+1.39 ± 1.09 kg, P < 0.001). Appendicular lean mass also decreased in RDA compared with 2RDA (P = 0.022), driven by a reduction in RDA (-0.64 ± 0.91 kg, P = 0.005 compared with 0.11 ± 0.57 kg, P = 0.592). Adjusting for energy imbalances did not alter these findings. Knee-extension peak power was also differently affected (P = 0.012; 26.6 ± 47.7 W, P = 0.015 in 2RDA compared with -11.7 ± 31.0 W, P = 0.180 in RDA).Conclusions: Consumption of a diet providing 2RDA for protein compared with the current guidelines was found to have beneficial effects on lean body mass and leg power in elderly men. These effects were not explained by differences in energy balance. This trial was registered at the Australia New Zealand Clinical Trial Registry (www.anzctr.org.au) as ACTRN12616000310460.

Dietary protein and bone health: a systematic review and meta-analysis from the National Osteoporosis Foundation ,

Background: Considerable attention has recently focused on dietary protein's role in the mature skeleton, prompted partly by an interest in nonpharmacologic approaches to maintain skeletal health in adult life.Objective: The aim was to conduct a systematic review and meta-analysis evaluating the effects of dietary protein intake alone and with calcium with or without vitamin D (Ca±D) on bone health measures in adults.Design: Searches across 5 databases were conducted through October 2016 including randomized controlled trials (RCTs) and prospective cohort studies examining 1) the effects of "high versus low" protein intake or 2) dietary protein's synergistic effect with Ca±D intake on bone health outcomes. Two investigators independently conducted abstract and full-text screenings, data extractions, and risk of bias (ROB) assessments. Strength of evidence was rated by group consensus. Random-effects meta-analyses for outcomes with ≥4 RCTs were performed.Results: Sixteen RCTs and 20 prospective cohort studies were included in the systematic review. Overall ROB was medium. Moderate evidence suggested that higher protein intake may have a protective effect on lumbar spine (LS) bone mineral density (BMD) compared with lower protein intake (net percentage change: 0.52%; 95% CI: 0.06%, 0.97%, I2: 0%; n = 5) but no effect on total hip (TH), femoral neck (FN), or total body BMD or bone biomarkers. Limited evidence did not support an effect of protein with Ca±D on LS BMD, TH BMD, or forearm fractures; there was insufficient evidence for FN BMD and overall fractures.Conclusions: Current evidence shows no adverse effects of higher protein intakes. Although there were positive trends on BMD at most bone sites, only the LS showed moderate evidence to support benefits of higher protein intake. Studies were heterogeneous, and confounding could not be excluded. High-quality, long-term studies are needed to clarify dietary protein's role in bone health. This trial was registered at www.crd.york.ac.uk as CRD42015017751.

Upregulation of Glucose Production by Increased Dietary Protein in the Adult Cat (Felis catus)

Domestic cats are strict carnivores with a high requirement for protein, from which they derive their energy and glucose needs. Shuttling of amino acid carbon through glucose may also increase utilization of amino acids that are normally oxidized as protein intake increases. The objective of this study was to measure the effect of dietary protein intake on endogenous glucose production in the cat. Eighteen cats from the colony at the Centre for Feline Nutrition at Massey University were fed one of three low carbohydrate diets containing 15, 45, or 65% of their metabolizable energy as crude protein. After 3 weeks, cats were administered a primed continuous infusion of [U‐13C] glucose for 5 hours and blood was sampled. Mass isotopomer distribution analysis of plasma glucose was used to determine glucose production. Endogenous glucose production from all sources was 1.2‐ and 1.3‐times greater in cats fed 45 and 65% crude protein compared to those fed 15% crude protein (P &lt; 0.05). Contribution of the Cori cycle to gluconeogenesis was not different among diets and averaged 32.6 ± 1.41%, whereas non‐Cori cycle flux of endogenous glucose production (net gluconeogenesis) was greater in cats fed 45 and 65% (1.92 vs 2.29 and 2.47 g glucose × kg BW−1 × d−1, P &lt; 0.05). Increased gluconeogenesis in cats fed high protein diets suggests that part of the increased rate of amino acid catabolism and oxidation in these cats is the result of increased amino acid carbon cycling through glucose.Support or Funding InformationResearch funding was provided by the Animals and Society Research Fund, BRCSRA.

Weight Loss‐Induced Changes in Muscle Protein Turnover in Young Men: Effects of Dietary Protein Intake and Resistance Exercise

A negative consequence of diet‐induced weight loss is the loss of lean body mass (LBM), particularly muscle mass, which is induced by an imbalance between rates of muscle protein synthesis (MPS) and muscle protein breakdown (MPB). Increased protein intake and resistance exercise during diet‐induced weight loss promote retention of LBM [1] by stimulating MPS. Currently, the relative contribution of MPS to hypoenergetic diet‐induced LBM loss, and the effect of protein intake and resistance exercise on these variables is not well characterized. In a single blind investigation, adult men (n=24, BMI=28.6±0.6kg/m2, age=22±1y) underwent 10 days of a controlled diet with a 40% reduction in energy intake to create an energy deficit, while performing unilateral resistance exercise and consuming either lower protein (LP) (1.2g/kg/d protein, n=12) or higher protein (HP) (2.4g/kg/d protein, n=12). Pre‐ and post‐intervention testing included DXA, primed constant infusion of ring‐[13C6]‐phenylalanine to measure acute MPS in the fasted state and skeletal muscle biopsies to measure gene and protein expression. Total weight loss (−1.7±0.1kg) and fat mass loss (−0.7±0.1kg) did not differ between groups; however, appendicular lean mass of the exercised leg was preserved compared to the rested leg in both groups (exercise= −0.1±0.1kg, rest= −0.4±0.1kg, p&lt;0.05). Mixed MPS was significantly reduced in both groups following weight loss (HP= −14±4% and LP= −27±2%, p&lt;0.05). In the exercised leg, mixed MPS was preserved in the lower protein group and elevated above baseline in the higher protein group (14±6% p&lt;0.05) 48 hrs following the last exercise bout. Gene expression of TRAF6 was increased in the rested leg of the lower protein group (p&lt;0.05), but there was no change in TRAF6 protein expression at any time point in either group. Gene expression of other targets in the ubiquitin‐proteasome and autophagic‐lysosomal pathways (Atrogin‐1, MuRF‐1, Foxo3a, LC3, Gabarapl1, Ulk2, Beclin1) did not change with weight loss in either group. Protein expression of p‐Foxo3a (Ser253) and p‐TSC2 (Thr1462) also did not change with weight loss in either group. These results suggest that reductions in MPS are the likely reason for LBM loss during the early phase of diet‐induced weight loss. Resistance exercise can help to preserve (LP) or even elevate (HP) rates of fasted MPS, which, in concordance with our earlier work [1], promotes LBM retention.Support or Funding InformationSupported by NSERC and OGS

Effect of dietary protein intake on the body composition and metabolic parameters of neutered dogs.

Neutering is a common veterinary recommendation and is often associated with obesity development. Thus, the aim of the present study was to evaluate the effects of two different amounts of protein intake by neutered dogs regarding maintenance energy requirement (MER), body composition, and biochemical and hormonal parameters. A total of fourteen healthy adult dogs were fed either a diet containing 59·7 g protein/1000 kcal (4184 kJ) (P60) or a diet with 94·0 g protein/1000 kcal (4184 kJ) (P94) for 26 weeks after neutering to maintain their body weight prior to neutering. A mixed model was fitted to verify diet, time and diet × time interaction effects on biochemical parameters, serum concentrations of insulin, glucagon, leptin and insulin-like growth factor-1 (IGF-1). MER and the body composition data were evaluated within diets (paired t test) and within times (unpaired t test). A time effect was found for fructosamine, TAG, total lipids and IGF-1 serum concentrations. The diet × time interaction was significant for glucagon (P < 0·05). No differences between diets in the MER within each time were found. However, there was a reduction in the MER of dogs fed the P60 diet 26 weeks after neutering (P = 0·042). The fat body mass of dogs fed the P60 diet increased (P < 0·05) after neutering, even without a body-weight change. Some of the biochemical parameters changed over time, but all remained within the normal range. For the period evaluated in the present study, a diet with 94·0 g of protein/1000 kcal (4184 kJ) metabolisable energy seems to be a beneficial nutritional strategy to maintain the MER and the body composition of dogs after neutering.

Effects of dietary protein intake on body composition changes after weight loss in older adults: a systematic review and meta-analysis.

The impact of dietary protein on body composition changes after older adults purposefully lose weight requires systematic evaluation : This systematic review and meta-analysis assessed the effects of protein intake (< 25% vs ≥ 25% of energy intake or 1.0 g/kg/d) on energy restriction-induced changes in body mass, lean mass, and fat mass in adults older than 50 years. PubMed, Cochrane, Scopus, and Google Scholar were searched using the keywords "dietary proteins," "body composition," "skeletal muscle," and "muscle strength." Two researchers independently screened 1542 abstracts. Information was extracted from 24 articles. Twenty randomized control trials met the inclusion criteria. Older adults retained more lean mass and lost more fat mass during weight loss when consuming higher protein diets.

The Relationship Between Dietary Intakes of Amino Acids and Bone Mineral Density Among Individuals with Spinal Cord Injury.

The effect of dietary protein intake on bone mineral density (BMD) has not been explained in patients with spinal cord injury (SCI). In this study, we looked at the relationship between BMD and higher protein intake in patients with SCI while controlling for possible confounders. Patients with SCI, who were referred to the Brain and Spinal Cord Injury Research Center between November 2010 and April 2012, were included in the study. In total, the dietary intakes of 103 patients were assessed by 24-hour dietary recall interviews. We used dual-energy X-ray absorptiometry to measure BMD in the femoral neck, trochanter, intertrochanteric zone, hip, and lumbar vertebras. Eighty-six men and 17 women participated in this study. Protein intake was negatively associated with the BMD of lumbar vertebrae (p = 0.001, r = -0.37 for T-score and p = 0.030, r = -0.24 for Z-score). The BMD of lumbar vertebrae were negatively associated with intake of tryptophan, isoleucine, lysine, cysteine, and tyrosine (p = 0.007, 0.005, 0.009, 0.008, and 0.008 for T-score, respectively). Higher intakes of threonine, leucine, methionine, phenylalanine, valine, and histidine were related to a lower BMD of lumbar vertebrae (p = 0.006, 0.010, 0.009, 0.010, 0.009, and 0.008 respectively for T-scores). We found that high protein intake led to a lower BMD of lumbar vertebrae in patients with SCI after controlling for confounders including demographic and injury-related characteristics and calcium intake. No relationship between higher amino acids intake and BMD of the femur and hip was detected. Intake of alanine, arginine, and aspartic acid were not related to BMD.

Effects of Dietary Protein Intake on Growth and Semen Quality in Broiler Breeder Males

One hundred and eighty six-week old chicks were randomly distributed in to three dietary groups, each with three replicate of 20 birds. Three experimental iso-caloric (2750 Kcal ME/kg) grower diets containing 12, 14 and 16 percent CP were assigned to each of the three treatment groups CP12, CP14, and CP16, respectively. The daily dietary allocation was based on an energy requirement model. Weekly feed consumption and BW data were recorded. On 25th week semen was collected from 10 birds of each treatment groups and semen quality parameters were studied. The net gain in body weight of CP16 group was 1498.44±49.20g and significantly (P≤0.05) higher than CP12 and CP14 groups without any significant difference between them. The semen volume (0.575±0.014 ml), spermatozoa concentration (5.081±0.044 millions/μl) as well as number of spermatozoa per ejaculation (2.77±0.022 billions) in CP12 group were significantly (P<0.05) higher than those of CP14 and CP16 diet group. The results of the present study indicated that a grower diet with 12% CP and 2750 kcal ME/kg diet fed during growing period (6 to 20 weeks) is adequate to control mature body weight and improve semen quality in broiler breeder males.

Protein intake in type 1 diabetes

Protein intake in type 1 diabetes

Associations Between Biomarker‐Calibrated Protein Intake and Bone Health in the Women's Health Initiative

OBJECTIVEThe effects of dietary protein intake on bone health are controversial. This study examined the relation between protein intake with bone mineral density (BMD) and fracture within the Women's Health Initiative (WHI).METHODSThe WHI recruited 161,806 women aged 65–79 into the WHI‐Observational Study (OS) and WHI‐Clinical Trial (CT) between 1993 and 1998. Fractures were collected annually (WHI‐OS) or semi‐annually (WHI‐CT) by questionnaire through 2011. BMD was measured at baseline and 6 years among 10,833 women using dual‐energy x‐ray absorptiometry. Protein and energy intake were assessed via the WHI Food Frequency Questionnaire and calibrated using regression equations established based on biomarkers of protein and energy intake. Cox (fracture) and linear (BMD) regression models were adjusted for confounders including age, race/ethnicity, and body mass index.RESULTSMedian calibrated protein intake was 14% of energy. Women consuming 20% higher calibrated protein were 9% less likely to have a hip fracture (95% CI= 1%‐15%). Each 20% increase in calibrated protein was associated with higher BMD for total body (mean 6‐year change 0.004 g/cm2, 95% CI = 0.001–0.007 g/cm2) and hip (0.003 g/cm2, 95% CI= 0.001–0.005 g/cm2).CONCLUSIONHigher protein intake was associated with reduced risk of hip fracture and better maintenance of BMD over time. These data suggest higher protein intake may be an intervention target for preserving bone health.Funded by NHLBI (WHI) and NIA (4R00AG035002).

417 DIETARY PROTEIN INTAKE AND BLOOD PRESSURE

Objective: We conducted a meta-analysis of randomized controlled trials to evaluate the effect of dietary protein intake on blood pressure (BP) in adults. Methods: To identify articles published before April 2011, we searched electronic databases including MEDLINE, EMBASE, Cochrane Library, Web of Science, and the registry of soy research trials, conducted a manual bibliography review, and consulted experts in the field. Search terms included randomized controlled trial, blood pressure, dietary proteins, dietary supplements, casein, soy, and meat. Forty randomized trials including 3,277 participants met the eligibility criteria and were included in the meta-analysis. Using a standardized protocol and data extraction form, two investigators independently abstracted data on study design, participant characteristics, intervention, and treatment outcomes. Net effects of protein on BP were pooled across trials using random-effects models. Results: Compared to carbohydrate, dietary protein was associated with significant decreases in mean systolic (SBP) and diastolic BP (DBP) (95% confidence intervals) of −1.76 (−2.33, −1.20) and −1.15 (−1.59, −0.71) mmHg, respectively (both P < 0.001). Both vegetable and animal protein were associated with significant BP decreases of −2.27 (−3.36, −1.18) and −2.54 (−3.55, −1.53) mmHg for SBP, respectively (both P < 0.001) and −1.26 (−2.26, −0.26) and −0.95 (−1.72, −0.19) mmHg for DBP, respectively (both P = 0.014). BP reduction was not significantly different when vegetable protein was compared directly to animal protein. Conclusions: Our findings indicate that partial replacement of carbohydrate with protein may be an important strategy for the prevention and treatment of hypertension.

Joint Effect of Dietary Protein Intake and Inflammation on Serum Albumin Level in Long-Term Maintenance Hemodialysis (MHD) Patients

Serum albumin is one of the strongest mortality-predictors in MHD patients. Yet, the degree to which serum albumin represents dietary protein intake or inflammation is not clear. We hypothesized that inadequate protein intake and inflammation contribute equally to hypoalbuminemia and examined correlates of low serum albumin Download : Download full-size image

The Influence of Higher Protein Intake and Greater Eating Frequency on Appetite Control in Overweight and Obese Men

The purpose of this study was to determine the effects of dietary protein intake and eating frequency on perceived appetite, satiety, and hormonal responses in overweight/obese men. Thirteen men (age 51 +/- 4 years; BMI 31.3 +/- 0.8 kg/m(2)) consumed eucaloric diets containing normal protein (79 +/- 2 g protein/day; 14% of energy intake as protein) or higher protein (138 +/- 3 g protein/day; 25% of energy intake as protein) equally divided among three eating occasions (3-EO; every 4 h) or six eating occasions (6-EO; every 2 h) on four separate days in randomized order. Hunger, fullness, plasma glucose, and hormonal responses were assessed throughout 11 h. No protein x eating frequency interactions were observed for any of the outcomes. Independent of eating frequency, higher protein led to greater daily fullness (P < 0.05) and peptide YY (PYY) concentrations (P < 0.05). In contrast, higher protein led to greater daily ghrelin concentrations (P < 0.05) vs. normal protein. Protein quantity did not influence daily hunger, glucose, or insulin concentrations. Independent of dietary protein, 6-EO led to lower daily fullness (P < 0.05) and PYY concentrations (P < 0.05). The 6-EO also led to lower glucose (P < 0.05) and insulin concentrations (P < 0.05) vs. 3-EO. Although the hunger-related perceived sensations and hormonal responses were conflicting, the fullness-related responses were consistently greater with higher protein intake but lower with increased eating frequency. Collectively, these data suggest that higher protein intake promotes satiety and challenge the concept that increasing the number of eating occasions enhances satiety in overweight and obese men.

Effect Of Dietary Protein Intake On Nitrogen Balance During Resistance Exercise Training

Effect Of Dietary Protein Intake On Nitrogen Balance During Resistance Exercise Training

Effects of dietary protein intake on lactation performance of the laboratory mouse, &lt;i&gt;Mus musculus&lt;/i&gt;

Laboratory mice (strain MF1) were used to investigate the effects of dietary protein content on lactation performance to test the heat dissipation limit hypothesis. The specific dynamic action (SDA) for high protein (HP) and high carbohydrate (HC) diets was measured using open-flow respirometry at 9.4% and 6.1%, respectively. The same two diets were fed ad libitum to mice during lactation. Mice fed on HP and HC diets at 21 ºC reached a plateau in their daily food intake at 12.3±0.2 g day-1 and 16.6±0.2 g day-1, respectively between days 12-17 of lactation. HP-fed mice had a significantly higher daily energy expenditure (DEE) measured by doubly labelled water and higher water turnover than HC-fed mice but the energy they exported as milk was significantly lower than that of HC-fed mice and therefore resulted in poor growth rate of their offspring. The urea production of HP-fed mice from their daily protein intake of 7.1 g was estimated at 1994 mg which required 10.2 mls of water per day to be cleared. The mice increased their urine production by 14.4 mls probably to eliminate this urea. High protein diet had negative effects on lactation, indicating the growth of pups in previous studies was not protein limited. The negative effects of the HP diet were due to the high DEE that greatly reduced the energy available for milk production, rather than a toxicity effect of the urea production. The different DEE of the two diets suggests that other factors were involved in the delivery of energy to the offspring.KEY WORDS: Laboratory mouse, dietary protein, specific dynamic action, and daily energy expenditure

Short-term protein intake increases fractional synthesis rate of muscle protein in the elderly: meta-analysis

The precise effects of protein intake on fractional synthesis rate (FSR) of muscle protein are still under debate. The sample size of these studies was small and the conclusions in young and elderly subjects were inconsistent. To assess the effect of dietary protein intake on the FSR level, we conducted a meta-analysis of controlled protein intake trials. Random-effects models were used to calculate the weighted mean differences (WMDs). Ten studies were included and effects of short-term protein intake were evaluated. In an overall pooled estimate, protein intake significantly increased the FSR (20 trials, 368 participants; WMD: 0.025%/h; 95%CI: 0.019-0.031; P < 0.0001). Meta-regression analysis suggested that the protein dose was positively related to the effect size (regression coefficient = 0.108%/h; 95%CI: 0.035, 0.182; P = 0.009). A subgroup analysis indicated that protein intake significantly increased FSR when the protein dose was ≤ 0.80 g/kg BW (16 trials, 308 participants; WMD: 0.027%/h; 95%CI: 0.019-0.031; P < 0.0001), but did not affect FSR when the protein dose was > 0.80 g/kg BW (4 trials, 60 participants; WMD: 0.016%/h; 95%CI: 0.004-0.029; P = 0.98). In conclusion, this study is the first integrated results showing that a short-term protein intake is effective at improving the FSR of muscle protein in the healthy elderly as well as young subjects. This beneficial effect seems to be dose-dependent when the dose levels of protein range from 0.08 to 0.80 g/kg BW.

Proteinuria and albumin homeostasis in the nephrotic syndrome: effect of dietary protein intake.

Nephrotic syndrome is analyzed in the light of interventions designed to decrease proteinuria and renal injury. The effect of dietary protein intake on urinary protein losses and albumin homeostasis are discussed on the basis of the pathophysiologic mechanisms known to account for changes in renal function of nephrotic patients. In addition, the effect of angiotensin-converting enzyme inhibitors for reduction of proteinuria is discussed in terms of the modulation of glomerular permselectivity and hemodynamics.