Effects of whey protein supplements on metabolism: evidence from human intervention studies

Whey proteins as a functional food: Health effects, functional properties, and applications in food

Functional foods are defined as foods and ingredients that exhibit health benefits beyond their nutritional value. Research on functional foods is increasing rapidly as they may help prevent and manage some non-communicable diseases. Whey proteins are recognized as a high-quality nutrient source and known to contain some bioactive components. They are rich in essential amino acids such as cysteine, branched-chain amino acids such as leucine, valine, and isoleucine, and bioactive peptides. Whey proteins look promising as a potential functional food, given its antioxidant, anti-inflammatory, blood pressure lowering, anti-obesity, and appetite suppressing effects that is discussed in the literature. Whey proteins also show functional properties that play an essential role in food processing as an emulsifier, fat-replacer, gelling and encapsulating agent and are known to improve sensory and textural characteristics of food. This review focuses on the functional food aspects of whey proteins, associated health effects, and current food applications.

Increased Protein with Decreased Carbohydrate Intake Reduces Postprandial Blood Glucose Levels in Women with Gestational Diabetes: The iPRO Study

Introduction

There is an urgent need to establish an evidence base for recommendations regarding proportions of macronutrients for optimized nutritional management of gestational diabetes mellitus (GDM). Our study compared isocaloric diets in women with GDM that differed in protein and carbohydrate content with fats held constant. We hypothesized that the glucose area under the curve (AUC) would be lower with the higher protein/lower carbohydrate diet.

Research Design and Methods

This study used a random order crossover design within a controlled research unit environment. Nineteen women were randomized to treatment, with 12 participants completing both arms of the study. Blood sampling occurred preprandially and at t = 30, 60, 120, and 180" relative to meals. Inclusion criteria were confirmed diet-controlled GDMA1, singleton gestation, and with no pre-existing medical comorbidities. Mean gestational age at entrance to study = 32 (±1.76) weeks. Mean prepregnant body mass index of participants = 28.7 (±5.3) kg/m2 Participants were randomly assigned initially to either an increased protein/low carbohydrate (iPRO30%/CHO35%) diet or a lower protein/higher carbohydrate (LPRO15%/CHO50%) diet for a 36 hour inpatient stay on the research unit. All meals and snacks were prepared in a metabolic kitchen. After a 3-7 day washout period, participants were randomized to the opposite treatment.

Results

On day 2 (with confirmed overnight fasting), the average 3-hour pre- through postprandial glucose AUC was lower in iPRO30%/CHO35% treatment arm (17395.20 ± 2493.47 vs. 19172.47 ± 3484.31, p = 0.01).

Conclusion

This study is the first to demonstrate that a higher protein, lower carbohydrate meal, especially at breakfast, can result in lower postprandial blood glucose values in women with gestational diabetes. A lack of statistically significant differences at other collection time points could have been due to several factors, but most likely due to small sample size. Longer term outcomes of a higher protein diet, including maternal glycemic control, nitrogen balance, and impact on fetal growth outcomes, are needed.

Effects of dietary protein-load and alkaline supplementation on acid-base balance and glucose metabolism in healthy elderly

BACKGROUND/OBJECTIVES

Metabolism is controlled by macro- and micronutrients. Protein-rich diets should lead to latent acidosis at tissue level with further negative implications. Food supplements with alkaline salts are available and popular pretending to prevent these changes.

SUBJECTS/METHODS

Within a randomised double-blind placebo-controlled trial we tested the hypotheses that (1) a 4-week protein-rich diet induces a latent tissue acidosis and (2) an alkaline supplement can compensate this. Acid-base balance and important metabolic parameters were determined before and after 4 weeks of supplementation by peripheral blood samples, indirect calorimetry and muscle microdialysis before and after a protein-rich test meal.

RESULTS

Fourty volunteers were randomised 1:1 to either verum or placebo supplements. Protein-rich diet by itself did not significantly affect acid-base balance. Alkaline supplementation increased plasma bicarbonate concentration without changing pH. Postprandial increases in serum glucose and insulin tended to be lower for verum vs. placebo. Resting and postprandial energy metabolism, and carbohydrate and fat oxidation did not differ significantly before and after supplementation in both groups. In muscle, postprandial glucose uptake and aerobic glucose oxidation were significantly higher for verum. In addition, verum significantly increased serum magnesium concentrations.

CONCLUSIONS

Four weeks of protein-rich diet did not significantly influence acid-base balance. However, alkaline supplementation improved systemic and tissue acid-base parameters and oxidative glucose metabolism.

Foods with Potential Prooxidant and Antioxidant Effects Involved in Parkinson's Disease

Oxidative stress plays a fundamental role in the pathogenesis of Parkinson's disease (PD). Oxidative stress appears to be responsible for the gradual dysfunction that manifests via numerous cellular pathways throughout PD progression. This review will describe the prooxidant effect of excessive consumption of processed food. Processed meat can affect health due to its high sodium content, advanced lipid oxidation end-products, cholesterol, and free fatty acids. During cooking, lipids can react with proteins to form advanced end-products of lipid oxidation. Excessive consumption of different types of carbohydrates is a risk factor for PD. The antioxidant effects of some foods in the regular diet provide an inconclusive interpretation of the environment's mechanisms with the modulation of oxidation stress-induced PD. Some antioxidant molecules are known whose primary mechanism is the neuroprotective effect. The melatonin mechanism consists of neutralizing reactive oxygen species (ROS) and inducing antioxidant enzyme's expression and activity. N-acetylcysteine protects against the development of PD by restoring levels of brain glutathione. The balanced administration of vitamin B3, ascorbic acid, vitamin D and the intake of caffeine every day seem beneficial for brain health in PD. Excessive chocolate intake could have adverse effects in PD patients. The findings reported to date do not provide clear benefits for a possible efficient therapeutic intervention by consuming the nutrients that are consumed regularly.

Whey protein supplementation reducing fasting levels of anandamide and 2-AG without weight loss in pre-menopausal women with obesity on a weight-loss diet

Background

Despite the importance of dairy proteins in modifying of metabolic abnormalities, no attention has been given to their effects on endocannabinoids.

Methods

A total number of 60 obese women were recruited in a 2-month randomized clinical trial. Following random allocation, they were assigned to one of the two groups: control (n = 30) and intervention (n = 30). Then, all the subjects followed a hypocaloric diet of 800 kcal below estimated energy needs. The intervention group received isocaloric weight-loss diet and whey protein powders (30 g/day). Baseline and 2-month fasting anthropometric, blood glucose, serum insulin, insulin resistance, lipid profile, AEA, and 2-AG were measured.

Results

The study groups were homogenous in terms of baseline characteristics (p > 0.05) except for MUFA intake (p = 0.021). There were no significant differences in energy and macronutrient intakes in the intervention group compared to the control group at the end of the study (p > 0.05). The results of the ANCOVA did not show significant reductions in body weight and BMI of the intervention group compared to the control group (p > 0.05); however, WC, body fat, FBS, AEA, 2-AG, total cholesterol, and triglyceride decreased and HDL-c significantly increased in the intervention group compared to the control group (p < 0.05).

Conclusions

In this study, the effects of simultaneous weight-loss diet and whey protein supplementation on the reduction of endocannabinoids were determined.

Trial registration

Iranian Registry of Clinical Trials IRCT2017021410181N8. Registered on March 2017.

MNX (Medium Duration Nutrition and Resistance-Vibration Exercise) Bed-Rest: Effect of Resistance Vibration Exercise Alone or Combined With Whey Protein Supplementation on Cardiovascular System in 21-Day Head-Down Bed Rest

Current inflight countermeasures do not completely prevent bone and cardiovascular changes induced by microgravity. High load Resistance Exercise combined with whole body Vibration (RVE) demonstrated benefits on bone and cardiovascular system during previous Head-Down Bed Rest (HDBR) studies. We examined the effectiveness of RVE alone or combined with a nutritional supplementation of Whey protein (NeX) on cardiovascular deconditioning. Eight male subjects (age 34 ± 8 years) in a crossover design completed three 21-day HDBR campaigns (Control-CON, RVE, and NeX). Pre and post HDBR Orthostatic Tolerance (OT) was evaluated by a 15-min head-up tilt test followed by increasing levels of Lower Body Negative Pressure (LBNP). Heart rate (HR), blood pressure (BP), and Sympathetic Index (ΣI) through spectral analysis were measured during OT test. Plasma Volume (PV), and Maximal Oxygen Uptake (VO2max) were measured before and after each campaign. Left ventricular mass, left ventricular end diastolic (LVEDV), end systolic (LVESV), stroke (SV) volumes, and circumferential deformation at rest and during an orthostatic stress simulated by a 30 mmHg LBNP were measured by cardiac MRI. RVE failed to prevent any change in these variables and NeX did not have any additional effect over exercise alone. In the 3 groups, (1) OT time dropped similarly (bed rest p < 0.001), (2) HR and ΣI were increased at rest at the end of HDBR and HR increased markedly during LBNP-tilt test, with inability to increase further the ΣI, (3) PV dropped (bed rest p < 0.001), along with LVEDV, LVESV and SV (p = 0.08, p < 0.001, and p = 0.045, respectively), (4) Left ventricle mass did not change significantly, (5) Deformation of the heart assessed by global circumferential strain was preserved and early diastolic circumferential strain rate was increased during orthostatic stress at the end of HDBR, illustrating preserved systolic and diastolic function respectively, without any difference between groups. Despite the drop in PV and LV volumes, RVE and NeX tended to alleviate the decrease in VO2max. In conclusion, RVE and NeX failed to prevent the cardiovascular deconditioning induced by a 21 day-HDBR.

Effectiveness of Resistive Vibration Exercise and Whey Protein Supplementation Plus Alkaline Salt on the Skeletal Muscle Proteome Following 21 Days of Bed Rest in Healthy Males

Muscle atrophy is a deleterious consequence of physical inactivity and is associated with increased morbidity and mortality. The aim of this study was to decipher the mechanisms involved in disuse muscle atrophy in eight healthy men using a 21 day bed rest with a cross-over design (control, with resistive vibration exercise (RVE), or RVE combined with whey protein supplementation and an alkaline salt (NEX)). The main physiological findings show a significant reduction in whole-body fat-free mass (CON -4.1%, RVE -4.3%, NEX -2.7%, p < 0.05), maximal oxygen consumption (CON -20.5%, RVE -6.46%, NEX -7.9%, p < 0.05), and maximal voluntary contraction (CON -15%, RVE -12%, and NEX -9.5%, p < 0.05) and a reduction in mitochondrial enzyme activity (CON -30.7%, RVE -31.3%, NEX -17%, p < 0.05). The benefits of nutrition and exercise countermeasure were evident with an increase in leg lean mass (CON -1.7%, RVE +8.9%, NEX +15%, p < 0.05). Changes to the vastus lateralis muscle proteome were characterized using mass spectrometry-based label-free quantitative proteomics, the findings of which suggest alterations to cell metabolism, mitochondrial metabolism, protein synthesis, and degradation pathways during bed rest. The observed changes were partially mitigated during RVE, but there were no significant pathway changes during the NEX trial. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the dataset identifier PXD006882. In conclusion, resistive vibration exercise, when combined with whey/alkalizing salt supplementation, could be an effective strategy to prevent skeletal muscle protein changes, muscle atrophy, and insulin sensitivity during medium duration bed rest.

Dairy Foods and Dairy Fats: New Perspectives on Pathways Implicated in Cardiometabolic Health

Low-fat and nonfat dairy products have been promoted as part of a healthy dietary pattern by both US dietary guidelines and professional organizations for several decades. The basis for this recommendation stems in part from the putative negative cardiometabolic effects associated with saturated fat consumption. However, as nutrition research has shifted from a single nutrient to a whole-food/dietary pattern approach, the role of dairy foods and dairy fat in the diet-disease relationship is being reexamined. Most observational and experimental evidence does not support a detrimental relationship between full-fat dairy intake and cardiometabolic health, including risks of cardiovascular disease and type 2 diabetes. Indeed, an expanded understanding of the dairy food matrix and the bioactive properties of dairy fats and other constituents suggests a neutral or potentially beneficial role in cardiometabolic health. To consider how consuming dairy foods, including full-fat dairy, is associated with cardiometabolic health, this review provides an innovative perspective on mechanisms that link dairy consumption to 3 main biological systems at the core of metabolic health, the gastrointestinal, hepatic, and vascular systems.

Protein intake and outcome in critically ill patients

PURPOSE OF REVIEW

The objective of this review is to describe the impact of protein intake on the outcomes of critically ill patients in the literature published in the preceding 2 years.

RECENT FINDINGS

Observational studies showed inconsistent results regarding the association of higher protein intake and outcomes of critically ill patients. Randomized controlled trials that directly compared higher versus lower protein intake in ICU patients are scarce, varied considerably in their designs and primary outcomes, and generally had relatively small differences in the amount of delivered protein between the study arms. Systematic reviews of existing studies showed no difference in mortality with higher protein intake. In addition, there is uncertainty regarding high protein provision in the early phase of critical illness.

SUMMARY

The optimal amount of protein intake in critically ill patients remains largely unclear and is considered a high priority for research. Ongoing clinical trials are likely to provide additional evidence on several important questions including the dose, timing, type of protein and the interaction with caloric intake and exercise.

High-fat diet leads to adiposity and adipose tissue inflammation: the effect of whey protein supplementation and aerobic exercise training

There is little understanding about dietary proteins and their potential contribution to obesity-induced inflammation. This study investigates the effect of 10 weeks of aerobic training and whey protein (WP) supplementation on visceral adipose tissue inflammation in rats fed a high-fat diet (HFD). In the first phase, which lasted 9 weeks, 40 male Wistar rats were randomly divided into 2 groups: (1) normal diet (n = 8), and (2) HFD (n = 32). In the second phase, rats fed an HFD were randomly assigned into 4 groups (n = 8/group): (1) sedentary, (2) WP, (3) aerobic training, and (4) WP + aerobic training. The aerobic training was performed for 10 weeks, 5 days/week at 21 m/min, 15% incline, for 60 min/day. HFD significantly increased body weight, adiposity index, fat pads weight, glucose levels, and insulin resistance index compared with the normal diet. Also, levels of tumor necrosis factor alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), hypoxia inducible factor 1 alpha (HIF-1α), and vascular endothelial growth factor A (VEGF-A) in adipose tissue and serum levels of TNF-α were increased in the HFD group. Glucose levels, insulin resistance index, and triglycerides were reduced only by WP, independently of aerobic training. Both the aerobic training and WP reduced the fat pads weight and levels of TNF-α, HIF-1α, and VEGF-A in adipose tissue. Nevertheless, the levels of MCP-1 in adipose tissue and serum levels of TNF-α and MCP-1 were not reduced significantly by WP or aerobic training. These findings suggest that both aerobic training and WP supplementation lead to a reduction in adiposity and ameliorate obesity-induced inflammation in visceral adipose tissue.

Whey Protein Concentrate WPC-80 Improves Antioxidant Defense Systems in the Salivary Glands of 14-Month Wistar Rats

Whey protein concentrate (WPC) is characterized by powerful antioxidant properties, but its effect on redox homeostasis of salivary glands of aging organisms is still unknown. In this study, we are the first to evaluate the antioxidant barrier of salivary glands of 14-month Wistar rats fed WPC-80. Total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), activities of glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) as well as concentrations of reduced glutathione (GSH) are estimated in the submandibular and parotid glands of rats administered WPC-80 intragastrically for a period of 7 and 14 days. We demonstrate a significant increase in GSH, GPx and SOD in the salivary glands of rats fed WPC-80 for 14 days and a significant increase in TAS, GPx and SOD in the parotid glands of rats fed WPC-80 for 7 days compared to control rats. The beneficial effects of WPC-80 on salivary glands are also demonstrated by lower TOS and OSI in the parotid glands of rats fed WPC-80 compared to the submandibular glands. In summary, we demonstrate that WPC-80 improves redox homeostasis in salivary glands, particularly in the parotid glands of old rats.

From Diabetes Care to Diabetes Cure-The Integration of Systems Biology, eHealth, and Behavioral Change

From a biological view, most of the processes involved in insulin resistance, which drives the pathobiology of type 2 diabetes, are reversible. This theoretically makes the disease reversible and curable by changing dietary habits and physical activity, particularly when adopted early in the disease process. Yet, this is not fully implemented and exploited in health care due to numerous obstacles. This article reviews the state of the art in all areas involved in a diabetes cure-focused therapy and discusses the scientific and technological advancements that need to be integrated into a systems approach sustainable lifestyle-based healthcare system and economy. The implementation of lifestyle as cure necessitates personalized and sustained lifestyle adaptations, which can only be established by a systems approach, including all relevant aspects (personalized diagnosis and diet, physical activity and stress management, self-empowerment, motivation, participation and health literacy, all facilitated by blended care and ehealth). Introduction of such a systems approach in type 2 diabetes therapy not only requires a concerted action of many stakeholders but also a change in healthcare economy, with new winners and losers. A "call for action" is put forward to actually initiate this transition. The solution provided for type 2 diabetes is translatable to other lifestyle-related disorders.

Integration of GWAS, pathway and network analyses reveals novel mechanistic insights into the synthesis of milk proteins in dairy cows

The quantities and proportions of protein fractions have notable effects on the nutritional and technological value of milk. Although much is known about the effects of genetic variants on milk proteins, the complex relationships among the set of genes and pathways regulating the different protein fractions synthesis and secretion into milk in dairy cows are still not completely understood. We conducted genome-wide association studies (GWAS) for milk nitrogen fractions in a cohort of 1,011 Brown Swiss cows, which uncovered 170 significant single nucleotide polymorphism (SNPs), mostly located on BTA6 and BTA11. Gene-set analysis and the network-based Associated Weight Matrix approach revealed that the milk proteins associated genes were involved in several biological functions, particularly ion and cation transmembrane transporter activity and neuronal and hormone signalling, according to the structure and function of casein micelles. Deeper analysis of the transcription factors and their predicted target genes within the network revealed that GFI1B, ZNF407 and NR5A1 might act as master regulators of milk protein synthesis and secretion. The information acquired provides novel insight into the regulatory mechanisms controlling milk protein synthesis and secretion in bovine mammary gland and may be useful in breeding programmes aimed at improving milk nutritional and/or technological properties.

Does whey protein supplementation affect blood pressure in hypoalbuminemic peritoneal dialysis patients?

Objective

Hypertension and hypoalbuminemia are common risk factors for cardiovascular complications in peritoneal dialysis (PD) patients. Data are limited regarding the effects of whey protein consumption on blood pressure in this population. The aim of the present study was to examine if whey protein supplementation for 12 weeks to hypoalbuminemic PD patients affects their blood pressure.

Patients and methods

This prospective randomized study included 36 stable PD patients with serum albumin levels <3.8 g/dL. During 12 weeks, 18 patients were instructed to consume 1.2 g/kg/day of protein and an additional whey protein supplement at a dose of 25% of the instructed daily protein (whey protein group). Eighteen patients were instructed to consume protein in the amount of 1.2 g/kg/day and an additional 25%, without whey protein supplementation (control group).

Results

Compared to the control group, in the whey protein group, serum albumin levels, oncotic pressure, and dialysate ultrafiltration significantly increased (3.55±0.14 to 4.08±0.15 g/dL, P<0.001; 21.81±2.03 to 24.06±1.54 mmHg, P<0.001; 927.8±120.3 to 1,125.0±125.1 mL/day, P<0.001; respectively) and were significantly higher after 12 weeks (4.08±0.15 vs 3.41±0.49 g/dL, P<0.001; 24.06±1.54 vs 22.71±1.77 mmHg, P=0.010; 1,125.0±125.1 vs 930.6±352.8 mL/day, P=0.017; respectively) in the whey protein group compared to the control group. Fluid overload, the extracellular to intracellular ratio and mean arterial pressure (MAP) significantly decreased (2.46±1.08 to 1.52±0.33, P<0.001; 1.080±0.142 to 0.954±0.124, P<0.001; 102.6±3.80 to 99.83±3.85, P=0.018; respectively) and were significantly lower in the whey protein group after 12 weeks (1.52±0.33 vs 2.23±0.73, P<0.001, 0.954±0.124 vs 1.048±0.111, P=0.002; 99.83±3.85 vs 102.8±3.93, P=0.018; respectively).

Conclusion

Whey protein supplementation for 12 weeks decreased MAP in hypoalbuminemic PD patients.

Bed rest and resistive vibration exercise unveil novel links between skeletal muscle mitochondrial function and insulin resistance

AIMS/HYPOTHESIS

Physical inactivity has broad implications for human disease including insulin resistance, sarcopenia and obesity. The present study tested the hypothesis that (1) impaired mitochondrial respiration is linked with blunted insulin sensitivity and loss of muscle mass in healthy young men, and (2) resistive vibration exercise (RVE) would mitigate the negative metabolic effects of bed rest.

METHODS

Participants (n = 9) were maintained in energy balance during 21 days of bed rest with RVE and without (CON) in a crossover study. Mitochondrial respiration was determined by high-resolution respirometry in permeabilised fibre bundles from biopsies of the vastus lateralis. A hyperinsulinaemic-euglycaemic clamp was used to determine insulin sensitivity, and body composition was assessed by dual-energy x-ray absorptiometry (DEXA).

RESULTS

Body mass (-3.2 ± 0.5 kg vs -2.8 ± 0.4 kg for CON and RVE, respectively, p < 0.05), fat-free mass (-2.9 ± 0.5 kg vs -2.7 ± 0.5 kg, p < 0.05) and peak oxygen consumption ([Formula: see text]) (10-15%, p < 0.05) were all reduced following bed rest. Bed rest decreased insulin sensitivity in the CON group (0.04 ± 0.002 mg kgFFM^-1 [pmol l^-1] min^-1 vs 0.03 ± 0.002 mg kgFFM^-1 [pmol l^-1] min^-1 for baseline vs post-CON), while RVE mitigated this response (0.04 ± 0.003 mg kgFFM^-1 [pmol l^-1] min^-1). Mitochondrial respiration (oxidative phosphorylation and electron transport system capacity) decreased in the CON group but not in the RVE group when expressed relative to tissue weight but not when normalised for citrate synthase activity. LEAK respiration, indicating a decrease in mitochondrial uncoupling, was the only component to remain significantly lower in the CON group after normalisation for citrate synthase. This was accompanied by a significant decrease in adenine nucleotide translocase protein content.

CONCLUSIONS/INTERPRETATION

Reductions in muscle mitochondrial respiration occur concomitantly with insulin resistance and loss of muscle mass during bed rest and may play a role in the adaptations to physical inactivity. Significantly, we show that RVE is an effective strategy to partially prevent some of the deleterious metabolic effects of bed rest.

Does Whey Protein Supplementation Improve the Nutritional Status in Hypoalbuminemic Peritoneal Dialysis Patients?

Limited data are available regarding the effects of whey protein on the nutritional status of the peritoneal dialysis population. This study evaluated the effects of whey protein supplementation for 12 weeks on the nutritional status in hypoalbuminemic peritoneal dialysis patients. Thirty-six stable adult patients on maintenance peritoneal dialysis with serum albumin levels <3.5 g/dL were enrolled in the study and were divided into two groups similar in their serum albumin and normalized protein equivalent of total nitrogen appearance (nPNA). Nineteen patients were instructed to receive 1.2 g/kg per day of protein diet and additional whey protein supplement at a dose of 25% of the instructed daily protein diet (whey protein group), and 17 patients were instructed to receive 1.2 g/kg per day protein diet without additional whey protein supplementation (control group). Nutritional status was assessed using two measures: nPNA and lean tissue mass index (LTI) obtained by whole-body bioimpedance spectroscopy technique. In the whey protein group serum albumin and nPNA significantly increased from baseline to week 6 (P < 0.001, P = 0.034; respectively) and from week 6 to week 12 (P < 0.001, P = 0.001; respectively); LTI significantly increased from week 6 to week 12 (P = 0.022). Compared to the control group at week 12, serum albumin, nPNA and LTI values were significantly higher in the whey protein group (P < 0.001, P = 0.002, P = 0.001; respectively). This study demonstrated for the first time that oral supplementation with whey protein improves nutritional status and is well tolerated in hypoalbuminemic PD patients.

The Consumption of Dairy Products Is Associated with Reduced Risks of Obesity and Metabolic Syndrome in Korean Women but not in Men

We aimed to investigate the association between dairy product consumption and the risk of obesity and metabolic syndrome (MetS) in Korean adults. Data from 13,692 Korean adults aged ≥19 years from the KNHANES 2010–2013 were used. The study participants were divided into three groups according to the serving size of dairy products they consumed based on a single 24-h recall. About 58% of the Korean adults did not consume any dairy products in one day. In both the sexes, only those who adhered to the recommendation for dairy products (≥1 serving/day) achieved the daily requirement of calcium. Women who consumed ≥1 serving/day of dairy products had lower risks of obesity (body mass index ≥ 25 kg/m²) (adjusted odds ratio (AOR), 0.77; 95% confidence interval (CI), 0.66–0.89; p for trend < 0.01) and MetS (AOR, 0.67; 95% CI, 0.56–0.80; p for trend < 0.01) than women who did not consume dairy products. However, these significant associations were not observed in men. In conclusion, consuming ≥ 1 serving/day of dairy products could be an easy and efficient strategy for meeting daily calcium requirement as well as lowering risks of obesity and MetS among Korean women.

Effects of a whey protein supplementation on oxidative stress, body composition and glucose metabolism among overweight people affected by diabetes mellitus or impaired fasting glucose: A pilot study

Obesity and diabetes mellitus type 2 (DM2) are characterized by chronic inflammation and oxidative stress [Donath et al. 2013] and this leads to cardiovascular diseases [Hulsmans & Holvoet 2010]. Whey proteins (WP) have antioxidant [Chitapanarux et al. 2009], anti-inflammatory [Sugawara et al. 2012] and hypoglycemic activities [Mignone et al. 2015], while data on weight, body composition [Frestedt et al. 2008; Aldrich et al. 2011] and blood pressure are conflicting [Kawase et al. 2000; Lee et al. 2007]. WP have unpleasant taste and smell [Patel 2015], but a new WP isolate (ProLYOtin®) seems to be more palatable. 40 g/die of ProLYOtin® were supplemented to overweight people (n=31) with impaired fasting glucose/DM2 for 12 weeks. Markers of antioxidant status (total antioxidant status, glutathione peroxidase, glutathione reductase, uric acid), oxidative damage (thiobarbituric acid reactive substances, advanced oxidation protein products, 8-hydroxydeoxyguanosine), inflammation (interleukin-6, high sensitive reactive protein C) and glicemic status (fasting glucose, insulin, glycated hemoglobin), anthropometric data (weight, height, waist circumference), body composition (body cell mass, fat mass), blood pressure, hand grip strength and skin autofluorescence were measured before and at the end of supplementation. Isolate palatability was evaluated. An increase in glutathione peroxidase, a decrease in uric acid and no change in glutathione reductase, total antioxidant status, oxidative damage, inflammation and glucose markers were found. Significant improvements in anthropometric parameters and fat mass were detected. There wasn't any change in blood pressure, skin autofluorescence and physical performance. Two-thirds of subjects judged the supplement positively. ProLYOtin® seems suitable for treatment of OS and overweight.

Correlations between the content of selected whey proteins in cow milk

The aim of the study was to determine the correlations between the concentrations of major whey proteins in cow milk. A total of 2,278 milk samples from Polish Holstein-Friesian (Black-and-White and Red-and-White varieties), Simmental and Jersey cows were analysed. In each sample the content of major whey proteins, i.e. α-lactalbumin, β-lactoglobulin, bovine serum albumin, lactoferrin and lysozyme were determined by the RP-HPLC method. Matrix scatter plots were prepared to determine the correlations between the concentrations of individual whey proteins. In the vast majority of cases a significant relationship was found between the content of individual whey proteins. Taking into account the production season and breed of cow, highly significant (p=0.001) negative correlation coefficients were obtained for the content of α-lactalbumin and bovine serum albumin, for α-lactalbumin and lysozyme, for β-lactoglobulin and bovine serum albumin, and for β-lactoglobulin and lysozyme. Positive correlations were observed for the concentrations of α-lactalbumin with β-lactoglobulin, lactoferrin and lysozyme, as well as for bovine serum albumin with lysozyme.

A role for whey-derived lactoferrin and immunoglobulins in the attenuation of obesity-related inflammation and disease

Obesity is a strong predictive factor in the development of chronic disease and has now superseded undernutrition as a major public health issue. Chronic inflammation is one mechanism thought to link excess body weight with disease. Increasingly, the gut and its extensive population of commensal microflora are recognized as playing an important role in the development of obesity-related chronic inflammation. Obesity and a high fat diet are associated with altered commensal microbial communities and increased intestinal permeability which contributes to systemic inflammation as a result of the translocation of lipopolysaccharide into the circulation and metabolic endotoxemia. Various milk proteins are showing promise in the prevention and treatment of obesity and chronic low-grade inflammation via reductions in visceral fat, neutralization of bacteria at the mucosa and reduced intestinal permeability. In this review, we focus on evidence supporting the potential antiobesogenic and anti-inflammatory effects of bovine whey-derived lactoferrin and immunoglobulins.

Lactoferrin potentially facilitates glucose regulation and enhances the incretin effect

Lactoferrin (Lf) is known for its physiologically pleiotropic properties. In this study, we investigated whether Lf affects glycemic regulation, including glucose absorption from the small intestine. Bovine Lf (bLf, 100 mg/kg body mass) was administered to rats by intraperitoneal injection before intravenous (intravenous glucose tolerance test, IVGTT) or oral glucose administration (oral glucose tolerance test, OGTT). With IVGTT, bLf pretreatment had no significant effect on plasma levels of glucose or insulin. With OGTT, the bLf treatment group tended to show lower plasma levels of glucose than the control group at and after the 15 min peak, and decreased levels of plasma glucose at 180 min. The change in plasma levels of insulin from 0 to 30 min was higher in the bLf treatment group than in the control group. Total plasma glucose-dependent insulinotropic polypeptide (GIP) was lowered at 60 min by the bLf treatment, while an immediate increase in total plasma glucagon-like peptide-1 (GLP-1) was observed within the bLf group undergoing OGTT. In addition, bLf was associated with an increase in the amount of glucose absorbed into the everted jejunum sac. These results suggest that Lf could suppress hyperglycemia, accompanied by elevated plasma levels of insulin via transiently accelerating GLP-1 secretion, and that Lf even enhances glucose absorption from the small intestine.

Lifestyle guidelines for managing adverse effects on bone health and body composition in men treated with androgen deprivation therapy for prostate cancer: an update

Background:

Men treated with androgen deprivation therapy (ADT) for prostate cancer are prone to multiple treatment-induced adverse effects, particularly with regard to a deterioration in bone health and altered body composition including decreased lean tissue mass and increased fat mass. These alterations may partially explain the marked increased risk in osteoporosis, falls, fracture and cardiometabolic risk that has been observed in this population.

Methods:

A review was conducted that assessed standard clinical guidelines for the management of ADT-induced adverse effects on bone health and body composition in men with prostate cancer.

Results:

Currently, standard clinical guidelines exist for the management of various bone and metabolic ADT-induced adverse effects in men with prostate cancer. However, an evaluation of the effectiveness of these guidelines into routine practice revealed that men continued to experience increased central adiposity, and, unless pharmacotherapy was instituted, accelerated bone loss and worsening glycaemia occurred.

Conclusions:

This review discusses the current guidelines and some of the limitations, and proposes new recommendations based on emerging evidence regarding the efficacy of lifestyle interventions, particularly with regard to exercise and nutritional factors, to manage ADT-related adverse effects on bone health and body composition in men with prostate cancer.

Supplementation of fermented Maillard-reactive whey protein enhances immunity by increasing NK cell activity

Objective: The objective of this study was to investigate the impact of supplementation with fermented Maillard-reactive whey protein (F-MRP) on natural killer (NK) cell activity, circulating cytokines, and serum protein levels.

Macronutrient Composition or Social Determinants? Impact on Infant Outcomes With Gestational Diabetes Mellitus

The purpose of this study was to examine, through a randomized, controlled trial, the effects of a maternal carbohydrate-restricted diet on maternal and infant outcomes in gestational diabetes mellitus (GDM). Women diagnosed with GDM were randomly allocated into one of two groups: an intervention group that was placed on a lower-carbohydrate diet (35-40% of total calories) or a control group that was placed on the usual pregnancy diet (50-55% carbohydrate). A convenience sample of participants diagnosed with GDM (ages 18-45 years) was recruited from two different sites: one urban and low-income and the other suburban and more affluent. Individual face-to-face diet instruction occurred with certified diabetes educators at both sites. Participants tested their blood glucose four times daily. Specific socioeconomic status indicators included enrollment in the Supplemental Nutrition Program for Women, Infants and Children or Medicaid-funded health insurance, as well as cross-sectional census data. All analyses were based on an intention to treat. Although there were no differences found between the lower-carbohydrate and usual-care diets in terms of blood glucose or maternal-infant outcomes, there were significant differences noted between the two sites. There was a lower mean postprandial blood glucose (100.59 ± 7.3 mg/dL) at the suburban site compared to the urban site (116.3 ± 15 mg/dL) (P <0.01), even though there was no difference in carbohydrate intake. There were increased amounts of protein and fat consumed at the suburban site (P <0.01), as well as lower infant complications (P <0.01). Further research is needed to determine whether these disparities in outcomes were the result of macronutrient proportions or environmental conditions.

Effect of whey protein on blood lipid profiles: a meta-analysis of randomized controlled trials

Previous studies have suggested that whey supplementation may have beneficial effects on lipid profiles, although results were inconsistent. A literature search was performed in March 2015 for randomized controlled trials observing the effects of whey protein and its derivatives on circulating levels of triacylglycerol (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). A meta-analysis was subsequently conducted. The meta-analysis results of 13 trials showed that whey supplementation significantly reduced the circulating TG level by 0.11 mmol/l (95% CI: -0.21, 0 mmol/l), whereas the whey protein had no effects on circulating TC (-0.11 mmol/l, 95% CI: -0.27, 0.05 mmol/l), LDL-C (-0.08 mmol/l, 95% CI: -0.23, 0.07 mmol/l) and HDL-C (0.01 mmol/l, 95% CI: -0.04, 0.05 mmol/l). Subgroup analysis showed that significant TG reduction disappeared in participants with low body mass index, low supplemental whey dose or under exercise training/energy restriction during the trial. No evidence of heterogeneity across studies and publication bias was observed. In conclusion, our findings demonstrated that the effects of whey protein supplementation were modest, with an overall lowering effect on TG but no effect on TC, LDL-C and HDL-C.

Morphological and Biochemical Effects on the Skeletal Muscle of Ovariectomized Old Female Rats Submitted to the Intake of Diets with Vegetable or Animal Protein and Resistance Training

Introduction. Sarcopenia is a process characterized by reduction in protein mass and muscle strength with increasing age, especially in the postmenopausal period, resulting in functional limitations and with great impact on the physical autonomy of the elderly. Objective. To evaluate the effects of diets with vegetable proteins (VP) or animal proteins (AP) associated with resistance training (RT) on the structural and biochemical parameters of the medial gastrocnemius muscle in Wistar rats with sarcopenia. Methods. An experimental model with ovariectomized rats was used to induce sarcopenia and resistance training. The histochemical technique was used for the typing of muscle fibers, the cross-sectional area of myocytes, and volume densities of myocytes and interstitium; the technique of Picrosirius stain was used to highlight the collagen fibers. Results. The VP diet was not able to minimize the effects of sarcopenia in the medial gastrocnemius of sedentary animals and when associated with RT, it promoted maintenance of the CSA, attenuating the atrophy of type IIB fibers in the medial gastrocnemius. The AP diet in sedentary animals protected the type I fibers. When combined with RT, the AP promoted muscle remodeling, with reduction in volume density of type I and IIA fibers, and increase of IIB fibers, together with an increase in collagen volume density. Conclusion. The data suggest a tendency to better results of hypertrophy in animal groups that consumed the AP diet, even the sedentary animals, although more evident in those trained.

Acute effect of red meat and dairy on glucose and insulin: a randomized crossover study

BACKGROUND

In contrast with some epidemiologic evidence, our previous research showed that a 4-wk diet that was high in low-fat dairy reduced insulin sensitivity compared with the effect of a diet that was high in red meat.

OBJECTIVE

We investigated whether a dairy meal would produce a greater insulin response than a carbohydrate-matched red meat meal would, which might account for the change in insulin sensitivity.

DESIGN

One meal contained lean red meat, bread, and orange juice, and the other meal contained skim milk, low-fat yogurt, cheese, and bread. Meals were isoenergetic, equal in macronutrient profile, and consumed 1 wk apart. Glucose, insulin, and triglycerides were measured before and 30, 60, 90, 120, 150, and 180 min after meal consumption. Differences between meals were tested with the use of a repeated-measures ANOVA and paired sample t tests.

RESULTS

Nineteen men and 24 women [mean ± SD age: 50.8 ± 16.0 y; body mass index (in kg/m(2)): 30.0 ± 3.5] completed the study. Twenty-two participants had normal glucose tolerance, and 21 participants had impaired fasting glucose or impaired glucose tolerance. The red meat meal resulted in a higher glucose response at 30 min after consumption (P < 0.001); however, the glucose total AUC was not different between meals (P = NS). The mean ± SEM incremental AUC (iAUC) for glucose was significantly higher after the dairy meal than after the red meat meal (2.23 ± 0.49 compared with 0.88 ± 0.57 mmol/L · 3 h, respectively; P = 0.004). The insulin total AUC and iAUC were not different between meals (iAUC: 159.65 ± 20.0 mU/L · 3 h for red meat compared with 167.49 ± 24.1 mU/L · 3 h for dairy; P = NS).

CONCLUSIONS

Lean red meat and low-fat dairy produced a similar glycemic response. The higher glucose response 30 min after consumption of the red meat meal was likely attributable to differences in the glycemic load between orange juice and milk and yogurt. An insulinotropic effect of dairy was not observed. This trial was registered at www.anzctr.org.au as ACTRN12615000164594.

Protective role of dairy and its constituents on vascular function independent of blood pressure-lowering activities

Greater intakes of dairy are frequently associated with reduced risk of cardiovascular disease. These observational studies have served as the basis for controlled interventions aimed at defining the cardioprotective mechanisms of dairy. Understanding these relationships is of public health importance because most of the US population fails to meet dietary recommendations for dairy, suggesting that many individuals could lower their cardiovascular disease risk by relatively simple dietary modification. Clinical studies investigating the acute ingestion of dairy or its constituents, including short-term (≤2 week) supplementation studies or those assessing postprandial responses, have largely shown benefits on vascular function without concomitant improvements in blood pressure. Chronic interventions have been less conclusive, with some showing benefits and others indicating a lack of improvement in vascular function regardless of blood pressure changes. Vasoprotective activities of dairy are likely mediated through improvements in nitric oxide bioavailability, oxidative stress, inflammation, and insulin resistance. Future controlled studies are needed to determine if these health benefits are mediated directly by dairy or indirectly by displacing other dietary components that otherwise impair vascular health.

Co-ingestion of essence of chicken to moderate glycaemic response of bread

Essence of chicken (EOC) beverage is a chicken meat extract, widely consumed in Asian countries for health benefits. EOC is a rich source of peptides and amino acids. White bread has become a popular staple food in all regions of Southeast Asia. A randomized controlled, crossover, non-blind trial was performed to investigate the role of EOC on glycaemic response (GR) of white bread. Ten healthy young subjects returned on five separate days for three glucose and two bread sessions. Subjects consumed bread or bread with EOC. The 120 min incremental area under the curve was significantly lower after consuming two bottles of EOC with bread than white bread alone. The glycaemic index (GI) of white bread was 83 and white bread with EOC 57. The co-ingestion of EOC may be a practical and simple way to reduce the GR of bread and other starch-based staples.

Food protein-derived bioactive peptides in management of type 2 diabetes

BACKGROUND

Type 2 diabetes (T2D), one of the major common human health problems, is growing at an alarming rate around the globe. Alpha-glucosidase and dipeptidyl peptidase IV (DPP-IV) enzymes play a significant role in development of T2D. Hence, reduction or inhibition of their activity can be one of the important strategies in management of T2D. Studies in the field of bioactive peptides have shown that dietary proteins could be natural source of alpha-glucosidase and DPP-IV inhibitory peptides.

PURPOSE

The purpose of this review is to provide an overview of food protein-derived peptides as potential inhibitors of alpha-glucosidase and DPP-IV with major focus on milk proteins.

METHODS

Efforts have been made to review the available information in literature on the relationship between food protein-derived peptides and T2D. This review summarizes the current data on alpha-glucosidase and dipeptidyl peptidase IV inhibitory bioactive peptides derived from proteins and examines the potential value of these peptides in the treatment and prevention of T2D. In addition, the proposed modes of inhibition of peptide inhibitors are also discussed.

RESULTS

Studies revealed that milk and other food proteins-derived bioactive peptides play a vital role in controlling T2D through several mechanisms, such as the satiety response, regulation of incretin hormones, insulinemia levels, and reducing the activity of carbohydrate degrading digestive enzymes.

CONCLUSIONS

The bioactive peptides could be used in prevention and management of T2D through functional foods or nutraceutical supplements. Further clinical trials are necessary to validate the findings of in vitro studies and to confirm the efficiency of these peptides for applications.

Dairy foods and dairy proteins in the management of type 2 diabetes: a systematic review of the clinical evidence

Type 2 diabetes mellitus (T2DM) is a growing public health concern affecting hundreds of millions of people worldwide and costing the global economy hundreds of billions of dollars annually. This chronic disease damages the blood vessels and increases the risk of other cardiometabolic ailments such as cardiovascular disease and stroke. If left unmanaged it can also lead to nerve damage, kidney damage, blindness, and amputation. For the most part, many of these symptoms can be prevented or reduced through simple dietary modifications and proper nutrition. Therefore, identifying relatively inexpensive and easily implementable dietary modifications for the prevention and management of T2DM is of considerable value to human health and healthcare modalities around the globe. Protein-rich dairy products have consistently been shown in epidemiologic studies to be beneficial for reducing the risk of developing T2DM. The clinical evidence regarding both dairy foods and dairy proteins (i.e., casein and whey protein) have shown promise for improving insulin secretion in individuals with T2DM. However, the clinical research on dairy protein supplementation in subjects with T2DM has been limited to acute studies. These studies have been mostly descriptive and have not been focused on important T2DM endpoints such as prevention, management, or treatment. Long-term studies are clearly needed to help researchers and medical professionals better understand the effects of consistent dairy protein intake on the metabolic health of humans with T2DM.

Consumption of a whey protein-enriched diet may prevent hepatic steatosis associated with weight gain in elderly women

BACKGROUND AND AIMS

Protein consumption has been associated with cardio-metabolic benefits, including weight loss and improved insulin sensitivity, and may have potential benefits for individuals with fatty liver disease (FLD). We investigated the effect of increasing dietary protein intake from whey relative to carbohydrate on hepatic steatosis.

METHODS AND RESULTS

A two-year randomized, double-blind, placebo-controlled trial of 30 g/day whey protein-supplemented beverage (protein) or an energy-matched low-protein high-carbohydrate beverage (control) for cardio-metabolic and bone health in 219 healthy elderly women, recruited from the Western Australian general population. Hepatic steatosis was quantified using computed tomographic liver-to-spleen (L/S) ratio. FLD was defined as liver-to-spleen difference <10 Hounsfield units. At baseline, FLD prevalence was 11.4%. Control and protein groups were similar in body mass index (BMI), insulin resistance, L/S ratio and FLD prevalence at baseline. At two-years, dietary protein increased by 20 g in the protein, but not the control, group. Total energy intake and physical activity remained similar between groups. At two-years, BMI and FLD prevalence increased in both groups, with no between group differences. L/S ratio increased in control, but not protein, group at two-years, with no between group differences. In a within group comparison, change in BMI correlated with changes in L/S ratio in control (r = 0.37, P = 0.0007), but not with protein group (r = 0.04, P = 0.73).

CONCLUSION

Increasing dietary protein intake from whey relative to carbohydrate does not reduce weight, hepatic steatosis or the prevalence of FLD in elderly women. However, it may prevent worsening of hepatic steatosis associated with weight gain.

CLINICAL TRIALS REGISTRATION

Australian New Zealand Clinical Trials Registry (Registration no. ACTRN012607000163404).

Desenvolvimento, caracterização e análise sensorial de formulações alimentares com proteínas do soro de leite ou albumina para crianças

O presente trabalho visou verificar a elaboração, a caracterização e a avaliação da aceitação de duas formulações alimentares achocolatadas (uma contendo albumina e a outra, concentrado proteico de soro de leite - WPC) para crianças de 7 a 10 anos. O desenvolvimento das formulações baseou-se nas recomendações nutricionais para a faixa etária. Foram avaliados os seguintes parâmetros físico-químicos: composição química, estabilidade, pH, viscosidade e fluidez. A análise sensorial englobou as escalas hedônica de atitude, intenção de consumo e doçura e foi realizada por um grupo de 142 julgadores de um centro universitário, com média de 24,5 ± 7,3 anos de idade e 66,2% do sexo feminino. Todos os dados obtidos foram submetidos à análise estatística, adotando-se p < 0,05 como nível de significância. A composição química não diferiu em base seca (p > 0,05). Observaram-se 3,88 (albumina) e 4,79 (WPC) vezes mais proteínas em 100 mL de amostra do que em bebidas comerciais. A primeira formulação mostrou-se mais viscosa (137,33 cP versus 22,33 cP da formulação com WPC) e menos fluida (percorreu 40 mL em 69 segundosversus 29 segundos da formulação com WPC). Quanto ao pH, o produto com albumina apresentou característica alcalina (8,60) e o com WPC ácida (6,28). Ambas as formulações permaneceram estáveis e homogêneas após 24 horas de visualização. A análise sensorial mostrou que as formulações foram similares em todos os testes aplicados (p > 0,05), sendo que as características mais bem avaliadas foram o sabor, a textura e a doçura, para ambas. Houve boa aceitação das formulações, com nota mediana de 7 e valores acima de 80% para a soma das respostas positivas nos testes. Conclui-se que as formulações alimentares analisadas apresentaram boas características físico-químicas e mostraram-se equilibradas nutricionalmente, com potencial para comercialização.

Evaluation of the Physicochemical Parameters of Functional Whey Beverages

The objective of this study is to determine the impact of the key technological parameters on the quality indices of functional beverages produced from whey and enriched with 0.2% of cold-pressed flaxseed oil, rich in ω-3 fatty acids. The amount of fatty acids, peroxide and anisidine values, fatty acidity, sedimentation and sensory parameters of whey beverages were estimated. It was found that the addition of flaxseed oil affected the sensory, physical and chemical properties of the beverages. High quantities of oleic and α-linolenic fatty acids (18.97 and 54.82%, respectively) and negligible amounts of palmitic and myristic acids (4.79 and 0.04%, respectively) were found in the product. On the basis of the obtained results, the beverages from whey enriched with flaxseed oil had a favourable ratio of n-6/n-3 polyunsaturated fatty acids and atherogenic and thrombogenic indices. The addition of a stabiliser and the pasteurisation of whey beverages with flaxseed oil did not affect the sensory parameters and the acidity of the products. The highest peroxide value (2.36 meq O₂/kg) and acidity (0.34%) were found in the samples with pH=4.0 after 30-day storage at (6±1) °С. A strong negative correlation was estimated between the amount of polyunsaturated fatty acids and anisidine value (R=-0.871; p<0.05), peroxide value (R=-0.728; p<0.05) and fatty acidity (R=-0.948; p<0.05).

Efficacy of Glutamine-Enriched Nutrition Support for Patients With Severe Acute Pancreatitis: A Meta-Analysis

BACKGROUND

Plasma glutamine (Gln) level has been negatively correlated with the severity of severe acute pancreatitis (SAP). Although Gln is widely used today, the results of individual randomized controlled trials of Gln-enriched nutrition support for patients with SAP are conflicting.

METHODS

PubMed, EMBASE, HighWire, Cochrane Central Register of Controlled Trials, Wanfang, China Journals Full-Text Database, and the Chinese Biomedical Literature Database were searched. Literature published before June 2014 was searched. Randomized controlled trials investigating the comparison of conventional and Gln-enriched nutrition support were included; a random effect model using Rev Man 5.2 software was chosen to complete this meta-analysis. The count data were analyzed using the risk ratio (RR) and 95% confidence interval (CI), and the measurement data were analyzed using the standard mean difference or weighted mean difference and 95% CI. Heterogeneity analyses were conducted by I(2) test; publication bias analyses were conducted by Begg test.

RESULTS

Ten studies were eventually chosen for analysis, including 218 patients who received conventional methods (control group) and 215 patients who received Gln-enriched nutrition support (experimental group). Compared with the control group, Gln is helpful in elevating the albumin level, decreasing C-reaction protein (standard mean difference = 1.01, -1.89; 95% CI: 0.50 to 1.51, -3.23 to -0.56; P < .05), decreasing the incidence of infectious complication and mortality (RR = 0.62, 0.36; 95% CI: 0.46 to 0.83, 0.16 to 0.83; P < .05), and shortening the hospital stay length (weighted mean difference [WMD] = -3.89; 95% CI: -4.98 to -2.81; P < .05) without increasing expenses (WMD = -0.16; 95% CI: -1.34 to 1.02; P > .05). Intravenous infusion manifested more advantages by decreasing the incidence of infectious complications and mortality.

CONCLUSIONS

Gln-enriched nutrition support is superior to conventional methods for SAP, and intravenous infusion may be a better choice for drug administration.

The effects of progressive resistance training combined with a whey-protein drink and vitamin D supplementation on glycaemic control, body composition and cardiometabolic risk factors in older adults with type 2 diabetes: study protocol for a randomized controlled trial

Background

While physical activity, energy restriction and weight loss are the cornerstone of type 2 diabetes management, less emphasis is placed on optimizing skeletal muscle mass. As muscle is the largest mass of insulin-sensitive tissue and the predominant reservoir for glucose disposal, there is a need to develop safe and effective evidence-based, lifestyle management strategies that optimize muscle mass as well as improve glycaemic control and cardiometabolic risk factors in people with this disease, particularly older adults who experience accelerated muscle loss.

Methods/Design

Using a two-arm randomized controlled trial, this 6-month study builds upon the community-based progressive resistance training (PRT) programme Lift for Life® to evaluate whether ingestion of a whey-protein drink combined with vitamin D supplementation can enhance the effects of PRT on glycaemic control, body composition and cardiometabolic health in older adults with type 2 diabetes. Approximately 200 adults aged 50 to 75 years with type 2 diabetes, treated with either diet alone or oral hypoglycaemic agents (not insulin), will be recruited. All participants will be asked to participate in a structured, supervised PRT programme based on the Lift for Life® programme structure, and randomly allocated to receive a whey-protein drink (20 g daily of whey-protein plus 20 g after each PRT session) plus vitamin D supplements (2000 IU/day), or no additional powder and supplements. The primary outcome measures to be collected at baseline, 3 and 6 months will be glycated haemoglobin (HbA_1c) and insulin sensitivity (homeostatic model assessment). Secondary outcomes will include changes in: muscle mass, size and intramuscular fat; fat mass; muscle strength and function; blood pressure; levels of lipids, adipokines and inflammatory markers, serum insulin-like growth factor-1 and 25-hydroxyvitamin D; renal function; diabetes medication; health-related quality of life, and cognitive function.

Discussion

The findings from this study will provide new evidence on whether increased dietary protein achieved through the ingestion of a whey-protein drink combined with vitamin D supplementation can enhance the effects of PRT on glycaemic control, muscle mass and size, and cardiometabolic risk factors in older adults with type 2 diabetes.

Trial registration

Australian New Zealand Clinical Trials ACTRN12613000592741.

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-15-431) contains supplementary material, which is available to authorized users.