Effects of different fractions of whey protein on postprandial lipid and hormone responses in type 2 diabetes. Eur J Clin Nutr. 2012;66:799-805. [PMID: 22588635 DOI: 10.1038/ejcn.2012.48]

Metabolic Syndrome and Biotherapeutic Activity of Dairy (Cow and Buffalo) Milk Proteins and Peptides: Fast Food-Induced Obesity Perspective-A Narrative Review

Metabolic syndrome (MS) is defined by the outcome of interconnected metabolic factors that directly increase the prevalence of obesity and other metabolic diseases. Currently, obesity is considered one of the most relevant topics of discussion because an epidemic heave of the incidence of obesity in both developing and underdeveloped countries has been reached. According to the World Obesity Atlas 2023 report, 38% of the world population are presently either obese or overweight. One of the causes of obesity is an imbalance of energy intake and energy expenditure, where nutritional imbalance due to consumption of high-calorie fast foods play a pivotal role. The dynamic interactions among different risk factors of obesity are highly complex; however, the underpinnings of hyperglycemia and dyslipidemia for obesity incidence are recognized. Fast foods, primarily composed of soluble carbohydrates, non-nutritive artificial sweeteners, saturated fats, and complexes of macronutrients (protein-carbohydrate, starch-lipid, starch-lipid-protein) provide high metabolic calories. Several experimental studies have pointed out that dairy proteins and peptides may modulate the activities of risk factors of obesity. To justify the results precisely, peptides from dairy milk proteins were synthesized under in vitro conditions and their contributions to biomarkers of obesity were assessed. Comprehensive information about the impact of proteins and peptides from dairy milks on fast food-induced obesity is presented in this narrative review article.

Protein Hydrolysates and Bioactive Peptides as Mediators of Blood Glucose-A Systematic Review and Meta-Analysis of Acute and Long-Term Studies

Type 2 diabetes mellitus (T2DM) is a major public health concern associated with high mortality and reduced life expectancy. Since diabetes is closely linked with lifestyle, not surprisingly, nutritional intervention and increased physical activity could play a vital role in attenuating the problems related to diabetes. Protein hydrolysates (PHs) and their bioactive peptides (BP) have been shown to exert a wide range of biological effects, including antioxidative, antihypertensive, and in particular, hypoglycaemic activities. To better understand the efficacy of such interventions, a systematic review and meta-analysis of randomised controlled trials (RCTs) were performed concerning the influence of protein hydrolysates on glycaemic biomarkers in subjects with and without hyperglycaemia. Five different databases were used to search for RCTs. In total, 37 RCTs were included in the systematic review and 29 RCTs in the meta-analysis. The meta-analysis revealed a significant reduction in postprandial blood glucose response (PPGR) in normoglycaemic (-0.22 mmol/L; 95% CI -0.43, -0.01; p ≤ 0.05) and in hyperglycaemic adults (-0.88 mmol/L; 95% CI -1.37, -0.39; p ≤ 0.001) compared with the respective control groups. A meta-regression analysis revealed a dose-dependent response for PPGR following PH consumption in normoglycaemic adults, specifically for doses ≤ 30 g. The postprandial blood insulin responses (PPIR) were significantly higher after the ingestion of PHs in both the group with and the group without hyperglycaemia, respectively (23.05 mIU/L; 95% CI 7.53, 38.57; p ≤ 0.01 and 12.57 mIU/L; 95% CI 2.72, 22.41; p ≤ 0.01), compared with controls. In terms of long-term responses, there was a small but significant reduction in both fasting blood glucose (FBG) and fasting glycated haemoglobin (HbA1c) in response to PH compared with the control group (p < 0.05). The PHs significantly improved the parameters of glycaemia in adults and, hence, it may contribute to the management and regulation of the future risk of developing T2DM.

Specific Genotypes Associated with Differences in Fasting Insulin Levels and Body Mass Index in Healthy Young Males: Implications for Gene-Nutrient Interactions-an Exploratory Study

Background

Genetic variation may significantly impact an individual's susceptibility to diseases, particularly when combined with specific nutrients. Additionally, genetic variations can lead to interindividual differences in metabolic responses.

Objective

The present study explores the association between gene variants and observed interindividual differences in metabolic responses.

Methods

The study included 30 healthy males (aged 20-34) who underwent a fasting period and subsequently consumed a standardized meal. Blood samples were collected both before and after the meal to assess metabolic changes. BMI served as an indirect measure for assessing physiological responses associated with body composition. Appetite changes were assessed using an online Visual Analog 100-point Scale. Buccal swabs were collected to analyze genetic variants in single nucleotide polymorphisms (SNPs).

Results

The data underwent multiple regression analysis, revealing significant associations with 3 SNPs and their metabolic status: the insulin-receptor substrate 1 (IRS1) gene variant rs2943641, genotypes CT and CC, with elevated fasting insulin levels (R2 = 0.639, P = < 0.0001); the mitochondrial uncoupling protein 1 (UCP1) gene variant rs1800592, genotypes GG and GA, with increased BMI (R2 = 0.261, P = 0.007); and the peroxisome proliferator-activated receptor γ2 (PPARγ2) gene variant rs1801282, genotypes GG and GC, with increased BMI (R2 = 0.200, P = 0.024).

Conclusions

Therefore, our study established significant associations between these 3 SNPs and differences in fasting insulin levels and BMI within our cohort.

Whey Protein Premeal Lowers Postprandial Glucose Concentrations in Adults Compared with Water-The Effect of Timing, Dose, and Metabolic Status: a Systematic Review and Meta-analysis

BACKGROUND

Serving whey protein before a meal in order to lower postprandial blood glucose concentrations is known as a premeal. The underlying mechanisms are only partly understood but may involve stimulation of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and insulin secretion together with a slower gastric emptying rate.

OBJECTIVES

The objective of this systematic review and meta-analysis was to review all randomized clinical trials investigating premeals with whey protein in comparison with a nonactive comparator (control) that evaluated plasma glucose, GLP-1, GIP, insulin, and/or gastric emptying rate. Secondary aims included subgroup analyses on the timing and dose of the premeal together with the metabolic state of the participants [lean, obese, and type 2 diabetes mellitus (T2DM)].

METHODS

We searched EMBASE, CENTRAL, PUBMED, and clinicaltrials.gov and found 16 randomized crossover trials with a total of 244 individuals. The last search was performed on 9 August, 2022.

RESULTS

Whey protein premeals lowered peak glucose concentration by -1.4 mmol/L [-1.9 mmol/L; -0.9 mmol/L], and the area under the curve for glucose was -0.9 standard deviation (SD) [-1.2 SD; -0.6 SD] compared with controls (high certainty). In association with these findings, whey protein premeals elevated GLP-1 (low certainty) and peak insulin (high certainty) concentrations and slowed gastric emptying rate (high certainty) compared with controls. Subgroup analyses showed a more pronounced and prolonged glucose-lowering effect in individuals with T2DM compared with participants without T2DM. The available evidence did not elucidate the role of GIP. The protein dose used varied between 4 and 55 g, and meta-regression analysis showed that the protein dose correlated with the glucose-lowering effects.

CONCLUSIONS

In conclusion, whey protein premeals lower postprandial blood glucose, reduce gastric emptying rate, and increase peak insulin. In addition, whey protein premeals may elevate plasma concentrations of GLP-1. Whey protein premeals may possess clinical potential, but the long-term effects await future clinical trials.

Benefits of Whey Proteins on Type 2 Diabetes Mellitus Parameters and Prevention of Cardiovascular Diseases

Type 2 diabetes mellitus (T2DM) is a major cause of morbidity and mortality, and it is a major risk factor for the early onset of cardiovascular diseases (CVDs). More than genetics, food, physical activity, walkability, and air pollution are lifestyle factors, which have the greatest impact on T2DM. Certain diets have been shown to be associated with lower T2DM and cardiovascular risk. Diminishing added sugar and processed fats and increasing antioxidant-rich vegetable and fruit intake has often been highlighted, as in the Mediterranean diet. However, less is known about the interest of proteins in low-fat dairy and whey in particular, which have great potential to improve T2DM and could be used safely as a part of a multi-target strategy. This review discusses all the biochemical and clinical aspects of the benefits of high-quality whey, which is now considered a functional food, for prevention and improvement of T2DM and CVDs by insulin- and non-insulin-dependent mechanisms.

Dairy bioactive proteins and peptides: a narrative review

Milk proteins are known for their high nutritional quality, based on their essential amino acid composition, and they exhibit a wide range of bioactivities, including satiety, antimicrobial, mineral-binding, and anti-lipidemic properties. Because of their unique water solubility, milk proteins are readily separated into casein and whey fractions, which can be further fractionated into many individual proteins, including alpha-S1- and alpha-S2-caseins, beta-casein, and kappa-casein, and the whey proteins alpha-lactalbumin, lactoferrin, beta-lactoglobulin, and glycomacropeptide. Many of these proteins have unique bioactivities. Further, over the past 30 years, peptides that are encrypted in the primary amino acid sequences of proteins and released along with amino acids during digestion are increasingly recognized as biologically active protein metabolites that may have beneficial effects on human health. This review examines the current state of the science on the contribution of dairy proteins and their unique peptides and amino acids to human health.

Whey Protein Supplementation Improves the Glycemic Response and May Reduce Non-Alcoholic Fatty Liver Disease Related Biomarkers in Women with Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) increases type 2 diabetes and non-alcoholic fatty liver disease (NAFLD) with insulin resistance. We hypothesized that a 35 g whey preload would improve insulin sensitivity and glucose handling while reducing biomarkers associated with NAFLD. Twenty-nine age-matched women (CON = 15, PCOS = 14) completed oral glycemic tolerance tests following baseline (Day 0) as well as an acute (Day 1) and short-term whey supplementation (Day 7). Whey had an interaction effect on glucose (p = 0.02) and insulin (p = 0.03), with glucose remaining stable and insulin increasing with whey supplementation. Insulin sensitivity (p < 0.01) improved with whey associated with increased glucagon secretion (p < 0.01). Alanine aminotransferase (ALT), and aspartate aminotransferase (AST) remained unchanged, but "day" had an effect on the AST:ALT ratio (p = 0.04), whereas triglycerides and sex hormone binding globulin overall were greater in the PCOS group (p < 0.05). Total cholesterol decreased in PCOS (by 13%) and CON (by 8%) (NS). HepG2 cells treated with plasma from participants before and after whey decreased lipid accumulation in the PCOS group after whey (p < 0.05). Whey provided an insulinogenic and glycemic homeostatic effect in women with PCOS with the potential to combat NAFLD-consequences.

Postprandial effects of a whey protein-based multi-ingredient nutritional drink compared with a normal breakfast on glucose, insulin, and active GLP-1 response among type 2 diabetic subjects: a crossover randomised controlled trial

Postprandial hyperglycaemia is recognised as an important target in type 2 diabetes management. Dietary pattern, meal composition, and amount of food intake are major factors for maintaining postprandial blood glucose levels. The aim of this study was to investigate the effect of consuming a whey protein-based multi-ingredient nutritional drink (WD) on postprandial glycaemic, insulinaemic, and active glucagon-like peptide-1 (GLP-1) responses in comparison to a typical breakfast, which is boiled white rice with chicken (BC) in patients with type 2 diabetes mellitus (T2DM). Fifteen subjects with T2DM participated in a randomised, controlled, cross-over study. Two isocaloric diets with similar nutrient composition were randomly tested with at least 7 d in between. Glucose, insulin, and active GLP-1 were measured by standard methods with blood samples collected with a venous catheter for 240 min during a kinetic test. The incremental area under the curve (iAUC_{0–240 min}) for plasma glucose was significantly lower after the consumption of WD (WD: 3551 ± 546; BC: 9610 ± 848 mg min/dl; P < 0⋅01), while insulinaemic response tended to be lesser (iAUC_{0–240 min}) than those of BC. In addition, higher iAUC_{0–240 min} for active GLP-1 was obtained with WD diet (WD: 2230 ± 441; BC: 925 ± 183 pM min/ml; P < 0⋅01). This study showed that WD can be used to replace a regular breakfast for improving postprandial glucose response and active GLP-1 levels in people with T2DM. Further studies are required to elucidate the clinical efficacy of WD on long-term glycaemic control in people with T2DM.

Bioactive peptides in the management of lifestyle-related diseases: Current trends and future perspectives

Lifestyle-related diseases constitute a major concern in the twenty-first century, with millions dying worldwide each year due to chosen lifestyles and associated complications such as obesity, type 2 diabetes, hypertension, and hypercholesterolemia. Although synthetic drugs have been shown to be quite effective in the treatment of these conditions, safety of these compounds remains a concern. Natural alternatives to drugs include food-derived peptides are now being explored for the prevention and treatment of lifestyle-related complications. Peptides are fragments nascent in the primary protein sequences and could impart health benefits beyond basic nutritional advantages. Evidence suggests that by controlling adipocyte differentiation and lipase activities, bioactive peptides may be able to prevent obesity. Bioactive peptides act as agents against type 2 diabetes because of their ability to inhibit enzymatic activities of DPP-IV, α-amylase, and α-glucosidase. Moreover, bioactive peptides can act as competitive inhibitors of angiotensin-converting enzyme, thus eliciting an antihypertensive effect. Bioactive peptides may have a hypocholesterolemic effect by inhibiting cholesterol metabolism pathways and cholesterol synthesis. This review addresses current knowledge of the impact of food-derived bioactive peptides on lifestyle diseases. In addition, future insights on the clinical trials, allergenicity, cytotoxicity, gastrointestinal stability, and regulatory approvals have also been considered.

Glucagon-like peptide-1 regulation by food proteins and protein hydrolysates

Glucagon-like peptide-1 (GLP-1) is an enterohormone with a key role in several processes controlling body homeostasis, including glucose homeostasis and food intake regulation. It is secreted by the intestinal cells in response to nutrients, such as glucose, fat and amino acids. In the present review, we analyse the effect of protein on GLP-1 secretion and clearance. We review the literature on the GLP-1 secretory effects of protein and protein hydrolysates, and the mechanisms through which they exert these effects. We also review the studies on protein from different sources that has inhibitory effects on dipeptidyl peptidase-4 (DPP4), the enzyme responsible for GLP-1 inactivation, with particular emphasis on specific sources and treatments, and the gaps there still are in knowledge. There is evidence that the protein source and the hydrolytic processing applied to them can influence the effects on GLP-1 signalling. The gastrointestinal digestion of proteins, for example, significantly changes their effectiveness at modulating this enterohormone secretion in both in vivo and in vitro studies. Nevertheless, little information is available regarding human studies and more research is required to understand their potential as regulators of glucose homeostasis.

Whey Proteins and Its Derivatives: Bioactivity, Functionality, and Current Applications

With the increased consumer demand for nutritional foods, it is important to develop value-added products, which will not only catch the attention of a wider consumer group but also provide greater benefits in terms of enhanced nutrition and functionality. Milk whey proteins are one of the most valued constituents due to their nutritional and techno-functional attributes. Whey proteins are rich in bioactive peptides, possessing bioactive properties such as being antioxidant and antihypertensive as well as having antimicrobial activities, which, when ingested, confers several health benefits. These peptides have the potential to be used as an active food ingredient in the production of functional foods. In addition to their bioactivities, whey proteins are known to possess enhanced functional attributes that allow them to be utilized in broad applications, such as an encapsulating agent or carrier materials to entrap bioactive compounds, emulsification, and in edible and active packaging. Hence, over the recent years, several whey protein-based ingredients have been developed and utilized in making formulations for a wide range of foods to harness their beneficial properties. This review highlights the bioactive properties, functional characteristics, associated processing limitations, and applications of different whey protein fractions and derivatives in the field of food formulations, encapsulation, and packaging.

The Clinical Application of Mealtime Whey Protein for the Treatment of Postprandial Hyperglycaemia for People With Type 2 Diabetes: A Long Whey to Go

Mitigating postprandial hyperglycaemic excursions may be effective in not only enhancing glycaemic control for people with type 2 diabetes but also reducing the onset of diabetes-related complications. However, there are growing concerns over the long-term efficacy of anti-hyperglycaemic pharmacotherapies, which coupled with their rising financial costs, underlines the need for further non-pharmaceutical treatments to regulate postprandial glycaemic excursions. One promising strategy that acutely improves postprandial glycaemia for people with type 2 diabetes is through the provision of mealtime whey protein, owing to the slowing of gastric emptying and increased secretion of insulin and the incretin peptides. The magnitude of this effect appears greater when whey protein is consumed before, rather than with, a meal. Herein, this dietary tool may offer a simple and inexpensive strategy in the management of postprandial hyperglycaemia for people with type 2 diabetes. However, there are insufficient long-term studies that have investigated the use of mealtime whey protein as a treatment option for individuals with type 2 diabetes. The methodological approaches applied in acute studies and outcomes reported may also not portray what is achievable long-term in practice. Therefore, studies are needed to refine the application of this mealtime strategy to maximize its clinical potential to treat hyperglycaemia and to apply these long-term to address key components of successful diabetes care. This review discusses evidence surrounding the provision of mealtime whey protein to treat postprandial hyperglycaemia in individuals with type 2 diabetes and highlights areas to help facilitate its clinical application.

The Influence of Different Foods and Food Ingredients on Acute Postprandial Triglyceride Response: A Systematic Literature Review and Meta-Analysis of Randomized Controlled Trials

The use of postprandial triglyceride (ppTG) as a cardiovascular disease risk indicator has gained recent popularity. However, the influence of different foods or food ingredients on the ppTG response has not been comprehensively characterized. A systematic literature review and meta-analysis was conducted to assess the effects of foods or food ingredients on the ppTG response. PubMed, MEDLINE, Cochrane, and CINAHL databases were searched for relevant acute (<24-h) randomized controlled trials published up to September 2018. Based on our selection criteria, 179 relevant trials (366 comparisons) were identified and systematically compiled into distinct food or food ingredient categories. A ppTG-lowering effect was noted for soluble fiber (Hedges' giAUC = -0.72; 95% CI: -1.33, -0.11), sodium bicarbonate mineral water (Hedges' gAUC = -0.42; 95% CI: -0.79, -0.04), diacylglycerol oil (Hedges' giAUC = -0.38; 95% CI: -0.75, -0.00), and whey protein when it was contrasted with other proteins. The fats group showed significant but opposite effects depending on the outcome measure used (Hedges' giAUC = -0.32; 95% CI: -0.61, -0.03; and Hedges' gAUC = 0.16; 95% CI: 0.06, 0.26). Data for other important food groups (nuts, vegetables, and polyphenols) were also assessed but of limited availability. Assessing for oral fat tolerance test (OFTT) recommendation compliance, most trials were ≥4 h long but lacked a sufficiently high fat challenge. iAUC and AUC were more common measures of ppTG. Overall, our analyses indicate that the effects on ppTG by different food groups are diverse, largely influenced by the type of food or food ingredient within the same group. The type of ppTG measurement can also influence the response.

Rapid gastric emptying in diabetes mellitus: Pathophysiology and clinical importance

Although slow gastric emptying (gastroparesis) is a well-known complication of chronic hyperglycemia in diabetes mellitus (DM), it recently has become clear that rapid gastric emptying also is a frequent and important diabetic complication. In contrast, acute hyperglycemia causes slow gastric emptying, and acute hypoglycemia causes rapid gastric emptying. Rapid gastric emptying is frequent in T2DM; however, it may also occur in T1DM, particularly in the early stages of the disease, but may persist even into late stages. Recent studies suggest that usually, the stomach restricts the emptying of nutrients to 1-4 kcals/min. This restriction is due to the action of the gastric 'braking' hormones such as GLP-1, leptin, and amylin acting via the gastric inhibitory vagal motor circuit (GIVMC). Disruption of this braking system leads to rapid gastric emptying. Acute hyperglycemia also slows gastric emptying by stimulating the GIVMC, while acute hypoglycemia causes rapid gastric emptying by stimulating the gastric excitatory vagal motor circuit (GEVMC). In contrast, chronic hyperglycemia causes rapid gastric emptying by inducing oxidative stress in the stomach wall that disrupts inhibitory neuromuscular transmission and increases the contractility of the smooth muscle, while chronic hyperglycemia may also cause slow gastric emptying via severe inflammatory stress caused by proinflammatory macrophages and reduce contractility of the smooth muscle. There is a bidirectional relationship between blood glucose and gastric emptying. Thus, rapid gastric emptying may lead to a sizeable postprandial spike, and slow gastric emptying may blunt it. Postprandial hyperglycemia is involved in the development, progression, and complications of DM. Correction of fast gastric emptying involves agents that activate GIVMC and the use of gastric 'braking' hormones or their analogs. Recognition and treatment of rapid gastric emptying may contribute to better management of postprandial hyperglycemia and prevention of some diabetic complications.

Milk in the prevention and management of type 2 diabetes: The potential role of milk proteins

Globally, diabetes mellitus is not only considered a leading cause of mortality and morbidities but has also created a substantial economic burden. There is growing evidence that foods and their components can be implemented in the prevention and management of type 2 diabetes mellitus (T2DM). Increased dairy consumption has been linked to a lower risk of T2DM. The protective role of dairy foods in the development of T2DM is thought to be largely attributable to dairy nutrients, one of them being dairy protein. There is considerable evidence that milk proteins increase the postprandial insulin response and lower the postprandial blood glucose response in both healthy subjects and patients with T2DM. The exact mechanisms by which milk proteins lower postprandial glucose levels are yet to established; however, the amino acids and bioactive peptides derived from milk proteins are thought to modify a physiological milieu, which includes delayed gastric emptying and the enhancement of incretin and insulin responses, consequently leading to lower postprandial glucose levels. The present review will focus on providing a clear presentation of the potential implementation of milk proteins as a dietary supplement in the prevention and management of T2DM by summarizing the relevant supporting evidence for this particular topic.

Effect of Nutrient and Micronutrient Intake on Chylomicron Production and Postprandial Lipemia

Postprandial lipemia, which is one of the main characteristics of the atherogenic dyslipidemia with fasting plasma hypertriglyceridemia, low high-density lipoprotein cholesterol and an increase of small and dense low-density lipoproteins is now considered a causal risk factor for atherosclerotic cardiovascular disease and all-cause mortality. Postprandial lipemia, which is mainly related to the increase in chylomicron production, is frequently elevated in individuals at high cardiovascular risk such as obese or overweight patients, type 2 diabetic patients and subjects with a metabolic syndrome who share an insulin resistant state. It is now well known that chylomicron production and thus postprandial lipemia is highly regulated by many factors such as endogenous factors: circulating factors such as hormones or free fatty acids, genetic variants, circadian rhythms, or exogenous factors: food components, dietary supplements and prescription drugs. In this review, we focused on the effect of nutrients, micronutrients and phytochemicals but also on food structure on chylomicron production and postprandial lipemia.

A pre-meal of whey proteins induces differential effects on glucose and lipid metabolism in subjects with the metabolic syndrome: a randomised cross-over trial

PURPOSE

Postprandial lipaemia (PPL), an independent risk factor for cardiovascular disease, is affected by composition and timing of meals. We evaluated if whey proteins (WP) consumed as a pre-meal before a fat-rich meal reduce postprandial triglyceride (TG) and apolipoprotein B-48 (ApoB-48) responses in subjects with the metabolic syndrome (MeS).

METHODS

An acute, randomised, cross-over trial was conducted. 20 subjects with MeS consumed a pre-meal of 0, 10 or 20 g WP 15 min prior to a fat-rich meal. The responses of TG and ApoB-48 were assessed. We also analysed postprandial responses of free fatty acids (FFA), glucose, insulin, glucagon, glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic peptide (GIP) and paracetamol (reflecting gastric emptying rates).

RESULTS

WP pre-meal did not alter the TG or ApoB-48 responses. In contrast, the insulin response was more pronounced after a pre-meal of 20 g WP than with 10 g WP (P = 0.0005) and placebo (P < 0.0001). Likewise, the postprandial glucagon response was greater with a pre-meal of 20 g WP than with 10 g WP (P < 0.0001) and 0 g WP (P < 0.0001). A pre-meal with 20 g of WP generated lower glucose (P = 0.0148) and S-paracetamol responses (P = 0.0003) and a higher GLP-1 response (P = 0.0086) than placebo. However, the pre-meal did not influence responses of GIP, FFA or appetite assessed by a Visual Analog Scale.

CONCLUSIONS

Consumption of a WP pre-meal prior to a fat-rich meal did not affect TG and chylomicron responses. In contrast, the WP pre-meal stimulates insulin and glucagon secretion and reduces blood glucose as expected, and delays gastric emptying. Consequently, our study points to a differential impact of a WP pre-meal on lipid and glucose metabolism to a fat-rich meal in subjects with MeS.

A small dose of whey protein co-ingested with mixed-macronutrient breakfast and lunch meals improves postprandial glycemia and suppresses appetite in men with type 2 diabetes: a randomized controlled trial

Background

Large doses of whey protein consumed as a preload before single high-glycemic load meals has been shown to improve postprandial glycemia in type 2 diabetes. It is unclear if this effect remains with smaller doses of whey co-ingested at consecutive mixed-macronutrient meals. Moreover, whether hydrolyzed whey offers further benefit under these conditions is unclear.

Objective

The aim of this study was to investigate postprandial glycemic and appetite responses after small doses of intact and hydrolyzed whey protein co-ingested with mixed-nutrient breakfast and lunch meals in men with type 2 diabetes.

Design

In a randomized, single-blind crossover design, 11 men with type 2 diabetes [mean ± SD age: 54.9 ± 2.3 y; glycated hemoglobin: 6.8% ± 0.3% (51.3 ± 3.4 mmol/mol)] attended the laboratory on 3 mornings and consumed 1) intact whey protein (15 g), 2) hydrolyzed whey protein (15 g), or 3) placebo (control) immediately before mixed-macronutrient breakfast and lunch meals, separated by 3 h. Blood samples were collected periodically and were processed for insulin, intact glucagon-like peptide 1 (GLP-1), gastric inhibitory polypeptide (GIP), leptin, peptide tyrosine tyrosine (PYY3-36), and amino acid concentrations. Interstitial glucose was measured during and for 24 h after each trial. Subjective appetite was assessed with the use of visual analog scales.

Results

Total postprandial glycemia area under the curve was reduced by 13% ± 3% after breakfast following the intact whey protein when compared with control (P < 0.05). Hydrolyzed whey attenuated early glucose after breakfast when compared with control (P < 0.05). Glycemia was improved postlunch after the intact whey protein only when compared with control (P < 0.05). Greater satiety was observed after the intact whey protein only after both meals when compared with control (P < 0.05). Insulin concentrations increased after both the intact and hydrolyzed whey protein, showing strong positive correlations with increases in valine and isoleucine (P < 0.05). Incretin and appetite regulatory hormone responses were similar across trials (P > 0.05).

Conclusions

The consumption of a small 15-g dose of intact whey protein immediately before consecutive mixed-macronutrient meals improves postprandial glycemia, stimulates insulin release, and increases satiety in men with type 2 diabetes. This trial was registered at www.clinicialtrials.gov as NCT02903199.

Whey protein lowers systolic blood pressure and Ca-caseinate reduces serum TAG after a high-fat meal in mildly hypertensive adults

Epidemiological studies show an inverse association between dairy consumption and blood pressure (BP) but there are few data on the postprandial effects of milk proteins. This study examined their effects, compared to maltodextrin, on postprandial BP and other CVD risk markers in volunteers with mild and pre-hypertension over an 8 h period. In this double-blinded, randomised, cross-over, controlled study 27 adults ingested a high-fat, isoenergetic breakfast and lunch with 28 g whey protein, 28 g Ca-caseinate or 27 g maltodextrin. Whey protein reduced systolic BP compared with Ca-caseinate (−15.2 ± 13.6 mmHg) and maltodextrin (−23.4 ± 10.5 mmHg) up to 5 h post-ingestion. There was an improvement in arterial stiffness after whey protein compared with maltodextrin (incremental Area Under the Curve- iAUC_0–8h: +14.4 ± 6.2%). Despite similar glucose levels after both whey protein and Ca-caseinate, whey protein induced a higher insulin response than Ca-caseinate (iAUC_0–8h: +219.5 ± 54.6 pmol/L). Ca-caseinate induced less suppression of non-esterified fatty acids than whey protein (iAUC_0–5h: −58.9 ± 135.5 μmol/L) and maltodextrin (iAUC_0–5h: −106.9 ± 89.4 μmol/L) and induced a smaller postprandial triacylglycerol response than whey protein (iAUC_0–8h: −1.68 ± 0.6 mmol/L). Milk proteins co-ingestion with high-fat meals may have the potential to maintain or improve CVD risk factors.

Recent Science and Clinical Application of Nutrition to Coronary Heart Disease

One of the greatest threats to mortality in industrialized societies continues to be coronary heart disease (CHD). Moreover, the ability to decrease the incidence of CHD has reached a limit utilizing traditional diagnostic evaluations and prevention and treatment strategies for the top five cardiovascular risk factors (hypertension, diabetes mellitus, dyslipidemia, obesity, and smoking). It is well known that about 80% of CHD can be prevented with optimal nutrition, coupled with exercise, weight management, mild alcohol intake, and smoking cessation. Among all of these factors, optimal nutrition provides the basic foundation for prevention and treatment of CHD. Numerous prospective nutrition clinical trials have shown dramatic reductions in the incidence of CHD. As nutritional science and nutrigenomics research continues, our ability to adjust the best nutrition with an individualized approach is emerging. This article reviews the role of nutrition in the prevention and treatment of CHD and myocardial infarction (MI).

Enzymatic digest of whey protein and wheylin-1, a dipeptide released in the digest, increase insulin sensitivity in an Akt phosphorylation-dependent manner

Wheylin-1 is the first whey-derived peptide that increases insulin sensitivity in an Akt phosphorylation-dependent manner and lowers blood glucose levels.

Yogurt and Cardiometabolic Diseases: A Critical Review of Potential Mechanisms

Associations between yogurt intake and risk of diet-related cardiometabolic diseases (CMDs) have been the subject of recent research in epidemiologic nutrition. A healthy dietary pattern has been identified as a pillar for the prevention of weight gain and CMDs. Epidemiologic studies suggest that yogurt consumption is linked to healthy dietary patterns, lifestyles, and reduced risk of CMDs, particularly type 2 diabetes. However, to our knowledge, few to no randomized controlled trials have investigated yogurt intake in relation to cardiometabolic clinical outcomes. Furthermore, there has been little attempt to clarify the mechanisms that underlie the potential beneficial effects of yogurt consumption on CMDs. Yogurt is a nutrient-dense dairy food and has been suggested to reduce weight gain and prevent CMDs by contributing to intakes of protein, calcium, bioactive lipids, and several other micronutrients. In addition, fermentation with bacterial strains generates bioactive peptides, resulting in a potentially greater beneficial effect of yogurt on metabolic health than nonfermented dairy products such as milk. To date, there is little concrete evidence that the mechanisms proposed in observational studies to explain positive results of yogurt on CMDs or parameters are valid. Many proposed mechanisms are based on assumptions that commercial yogurts contain strain-specific probiotics, that viable yogurt cultures are present in adequate quantities, and that yogurt provides a minimum threshold dose of nutrients or bioactive components capable of exerting a physiologic effect. Therefore, the primary objective of this review is to investigate the plausibility of potential mechanisms commonly cited in the literature in order to shed light on the inverse associations reported between yogurt intake and various cardiometabolic health parameters that are related to its nutrient profile, bacterial constituents, and food matrix. This article reviews current gaps and challenges in identifying such mechanisms and provides a perspective on the research agenda to validate the proposed role of yogurt in protecting against CMDs.

Effects of Alpha-Lactalbumin or Whey Protein Isolate on Muscle Damage, Muscle Pain, and Mood States Following Prolonged Strenuous Endurance Exercise

This study compared the effect of alpha-lactalbumin and whey protein on muscle damage, muscle pain, and mood states during short term recovery following strenuous prolonged exercise. In a two-stage crossover counterbalanced design, 12 endurance male runners were recruited (age: 30.4 ± 2.8 year, height: 172.7 ± 5.6 cm, body mass: 66.7 ± 6.5 kg, VO_2max: 58.0 ± 6.9 ml/kg⁻/min), ran for 90 min at 70% VO_2max, and followed by a 4-h recovery. Two treatments (carbohydrate+alpha-lactalbumin, CA; carbohydrate+whey protein isolate, CW) were applied during the main trials. During the first 2-h of recovery, CHO was served at the rate of 0.66 g/kg/h and PRO at 0.34 g/kg/h every 30 min. Creatine kinase (CK), interleukin-6 (IL-6), salivary cortisol, rating of muscle pain, pressure pain threshold (PPT), and mood states were evaluated before (Pre-ex), immediately (Post-ex0), 2 h (Post-ex2h) and 4 h (Post-ex4h) after exercise. 24 h after exercise (Post-ex24h), CK and IL-6, muscle pain, and PPT were evaluated. Compared with Pre-ex, Post-ex24h CK was higher in both trials of CA (398.16 ± 41.37 vs. 184.77 ± 22.68 IU/L, P = 0.039) and CW (418.17 ± 67.86 vs. 202.41 ± 22.26 IU/L, P = 0.037). IL-6 was also higher than Pre-ex at Post-ex0 and Post-ex2h in trials of CA (Post-ex0 vs. Pre-ex0: 7.87 ± 0.74 vs. 1.69 ± 0.23, P < 0.01; Post-ex2h vs. Pre-ex0: 5.39 ± 0.88 vs. 1.69 ± 0.23, P = 0.02) and CW (Post-ex0 vs. Pre-ex0: 8.63 ± 1.06 vs. 1.59 ± 0.19, P < 0.01; Post-ex2h vs. Pre-ex0: 5.75 ± 1.33 vs. 1.59 ± 0.19, P < 0.01). No difference was found in CK and IL-6 between two trials at all time points (all P > 0.05). Compared with Pre-ex0, salivary cortisol was elevated at Post-ex0 in both trials (CA: 0.96 ± 0.13 vs. 0.41 ± 0.05 ng/ml, P < 0.01; CW: 1.15 ± 0.18 vs. 0.43 ± 0.06 ng/ml, P < 0.01) and was lower at Post-ex24h than Pre-ex in CA trial (0.17 ± 0.02 vs. 0.41 ± 0.05 ng/ml, P < 0.01). Compared with CW, PPT was higher at Post-2h in CA trial (31.55 ± 3.09 vs. 26.99 ± 2.32 N/cm², P < 0.01). Compared with Post-ex0, feeling of fatigue was lower at Post-ex2h (P = 0.014) and Post-ex4h (P < 0.01) in CA, while it was lower at Post-ex4h (P = 0.038) in CW. Compared with CW, feeling of fatigue was marginally lower in the CA trial at Post-ex2h (P = 0.056). In conclusion, compared with the co-ingestion of CHO and whey PRO isolate, co-ingestion of CHO and alpha-lactalbumin reduced sensitivity to the muscle pain, attenuated feeling of fatigue and was more beneficial to reduce the feeling of fatigue and cortisol responses during 4-h recovery following 90-min running at 70% VO_2max.

The role of whey protein in postprandial glycaemic control

Epidemiological studies demonstrate that poor glycaemic control is an independent risk factor for CVD. Postprandial glycaemia has been demonstrated as a better predictor of glycated Hb, the gold standard of glycaemic control, when compared with fasting blood glucose. There is a need for more refined strategies to tightly control postprandial glycaemia, particularly in those with type 2 diabetes, and nutritional strategies around meal consumption may be effective in enhancing subsequent glycaemic control. Whey protein administration around meal times has been demonstrated to reduce postprandial glycaemia, mediated through various mechanisms including an enhancement of insulin secretion. Whey protein ingestion has also been shown to elicit an incretin effect, enhancing the secretion of glucose-dependent insulinotropic peptide and glucagon-like peptide-1, which may also influence appetite regulation. Acute intervention studies have shown some promising results however many have used large dosages (50-55 g) of whey protein alongside high-glycaemic index test meals, such as instant powdered potato mixed with glucose, which does not reflect realistic dietary strategies. Long-term intervention studies using realistic strategies around timing, format and amount of whey protein in relevant population groups are required.

Comparison of the Effects of Goat Dairy and Cow Dairy Based Breakfasts on Satiety, Appetite Hormones, and Metabolic Profile

The satiating effects of cow dairy have been thoroughly investigated; however, the effects of goat dairy on appetite have not been reported so far. Our study investigates the satiating effect of two breakfasts based on goat or cow dairy and their association with appetite related hormones and metabolic profile. Healthy adults consumed two breakfasts based on goat (G-Breakfast) or cow (C-Breakfast) dairy products. Blood samples were taken and VAS tests were performed at different time points. Blood metabolites were measured and Combined Satiety Index (CSI) and areas under the curves (AUC) were calculated. Desire to eat rating was significantly lower (breakfast &amp; time interaction p < 0.01) and hunger rating tended to be lower (breakfast &amp; time interaction p = 0.06) after the G-breakfast. None of the blood parameters studied were different between breakfasts; however, AUC_GLP-1 was inversely associated with the AUC_hunger and AUC_{desire-to-eat} after the G-Breakfast, whereas triglyceride levels were directly associated with AUC_CSI after the C-Breakfast. Our results suggest a slightly higher satiating effect of goat dairy when compared to cow dairy products, and pointed to a potential association of GLP-1 and triglyceride levels with the mechanisms by which dairy products might affect satiety after the G-Breakfast and C-Breakfast, respectively.

Fortification of the whey protein isolate antioxidant and antidiabetic activity with fraction rich in phenolic compounds obtained from Stevia rebaudiana (Bert.). Bertoni leaves

A stevia fraction (ASF) free of steviol glycosides was extracted from Stevia rebaudiana leaves (Stevia UEM-13). ASF essentially constitutes phenolic compounds (52.42%), which were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS) as caffeic acid, quercetin-3-o-glycoside, cyanidin-3-glucoside, kaempferol, quercetin, apigenin, rozmarinic acid, chlorogenic acid and dicaffeoylquinic acid. ASF was used as a multi-functional source of phenolic compounds to fortify the whey protein isolate (WPI) obtained by membrane separation. WPI fortified with 0.2% ASF showed an 80% increase in its antioxidant activity and more pronounced antidiabetic effects than the unfortified WPI, mainly in the glycemic control of diabetic animals induced by streptozotocin. The in vitro and in vivo antioxidant effects of ASF may enhance the effects of WPI. Indeed, this pioneering study revealed that ASF can be used to enrich the antioxidant and antidiabetic properties of WPI.

Dietary bioactive peptides: Human studies

Current opinion strongly links nutrition and health. Among nutrients, proteins, and peptides which are encrypted in their sequences and released during digestion could play a key role in improving health. These peptides have been claimed to be active on a wide spectrum of biological functions or diseases, including blood pressure and metabolic risk factors (coagulation, obesity, lipoprotein metabolism, and peroxidation), gut and neurological functions, immunity, cancer, dental health, and mineral metabolism. A majority of studies involved dairy peptides, but the properties of vegetal, animal, and sea products were also assessed. However, these allegations are mainly based on in vitro and experimental studies which are seldom confirmed in humans. This review focused on molecules which were tested in humans, and on the mechanisms explaining discrepancies between experimental and human studies.

Glucose-lowering effect of whey protein depends upon clinical characteristics of patients with type 2 diabetes

OBJECTIVE

Whey protein (WP) intake has been shown to reduce postprandial glycemia. Majority of WP research in type 2 diabetes (T2DM) involved acute challenge or weight loss studies. It is not known if WP supplementation can provide sustained glucose lowering. Our goal was to investigate the effects of WP on glycemia comprehensively by using continuous glucose monitoring (CGM) while avoiding the confounding effects of variable food intake through controlled feeding.

RESEARCH DESIGN AND METHODS

This double-blinded and placebo (PL)-controlled study included 22 patients with T2DM patients (11 male, 11 female; age 57.1±12.6 years) on diet or metformin monotherapy. First, one serving (21 g) of WP was compared with PL in parallel-armed acute challenge studies. Next, in a crossover design, each patient underwent CGM twice, over 2 consecutive weeks, 3.5 days each week. Identical diets were provided by the study during both CGM periods. During the first CGM, one serving of either WP or PL was consumed before breakfast and another before dinner. During the second CGM, participants switched to the alternate supplement. Order of the supplements was randomized.

RESULTS

During acute challenge studies, WP stimulated insulin and glucagon-like peptide (GLP)-1 secretion; suppressed ghrelin (all p<0.05), while PL had no effect. During CGM, glucose response to WP varied depending on the baseline characteristics of the patients. When evaluated using linear regression, the most predictive baseline variables were body mass index (BMI) (p=0.0006), triglycerides (p=8.3×10^-5) and GLP-1 (p=0.006). Lower BMI, triglyceride and GLP-1 predicted decreased glucose levels on WP. Obesity, hypertriglyceridemia and high fasting GLP-1 concentrations predicted increased glucose levels.

CONCLUSIONS

Effects of WP supplementation on glycemia in T2DM depend on the baseline characteristics. Lower body weight, normal triglyceride and lower GLP-1 levels predict glucose lowering. In contrast, obesity, hypertriglyceridemia and high baseline GLP-1 predict increased glucose response.

Insulinotropic Effects of Whey: Mechanisms of Action, Recent Clinical Trials, and Clinical Applications

BACKGROUND

The insulinotropic effect of whey protein is not fully understood and has clinical implications in the regulation of chronic and acute hyperglycemia.

SUMMARY

This review describes the composition of whey protein and potential mechanisms through which whey exerts an insulinotropic effect, including increasing the gastric emptying rate, effect on incretin hormones particularly gastric inhibitory peptide and glucagon-like polypeptide-1, and whey's role as a dipeptidyl peptidase IV inhibitor. Recent clinical evidence on the use of whey protein concentrate, isolate and hydrolysate in the management of type 2 diabetes and in the acute care adult population is reviewed.

KEY MESSAGES

The mechanism through which whey protein exerts its insulinotropic effect is multifactorial. Increasing evidence supports the potential use of whey protein in medical/nutritional therapy to manage glycemia; however, additional research is needed to determine the most appropriate dose, form and delivery method for whey supplementation.

Esophageal and Gastric Dysmotilities are Associated with Altered Glucose Homeostasis and Plasma Levels of Incretins and Leptin

BACKGROUND

Gastrointestinal complications in diabetes may affect glucose and endocrine homeostasis. Glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1), and leptin regulate glucose homeostasis, food intake, and gastric emptying.

AIM

The aim was to investigate associations between diabetes complications and glucose homeostasis and plasma levels of GIP, GLP-1, and leptin.

METHODS

Sixteen diabetes patients (seven men) were examined with gastric emptying scintigraphy and 72-h continuous subcutaneous glucose monitoring, 14 with the deep-breathing test, and 12 with esophageal manometry. A fiber-rich breakfast was given during the second day of glucose registration. Blood samples were taken 10 min and right before a fat-rich breakfast, as well as 10, 20, 30, 45, 60, 90, 120, 150, and 180 min afterwards. 20 healthy volunteers acted as controls. Plasma was analyzed regarding GIP, GLP-1, and leptin by Luminex.

RESULTS

Gastroparesis lowered maximal concentration (c-max) (p = 0.003) and total area under the curve (tAUC) (p = 0.019) of glucose levels as well as d-min (p = 0.043) of leptin levels. It tended to lower baseline (p = 0.073), c-max (p = 0.066), change from baseline (d-max) (p = 0.073), and tAUC (p = 0.093) of GLP-1 concentrations. Esophageal dysmotility tended to lower tAUC of glucose levels (p = 0.063), and c-min (p = 0.065) and tAUC (p = 0.063) of leptin levels. Diabetes patients had a higher baseline concentration of glucose (p = 0.013), GIP (p = 0.023), and leptin (p = 0.019) compared with healthy subjects.

CONCLUSIONS

Gastric and esophageal dysmotility are associated with both lesser increases in postprandial glucose elevations and decreased postprandial changes in GLP-1 and leptin.

Can milk proteins be a useful tool in the management of cardiometabolic health? An updated review of human intervention trials

The prevalence of cardiometabolic diseases is a significant public health burden worldwide. Emerging evidence supports the inverse association between greater dairy consumption and reduced risk of cardiometabolic diseases. Dairy proteins may have an important role in the favourable impact of dairy on human health such as blood pressure (BP), blood lipid and glucose control. The purpose of this review is to update and critically evaluate the evidence on the impacts of casein and whey protein in relation to metabolic function. Evidence from short-term clinical studies assessing postprandial responses to milk protein ingestion suggests benefits on vascular function independent of BP, as well as improvement in glycaemic homeostasis. Long-term interventions have been less conclusive, with some showing benefits and others indicating a lack of improvement in vascular function. During chronic consumption BP appears to be lowered and both dyslipidaemia and hyperglacaemia seem to be controlled. Limited number of trials investigated the effects of dairy proteins on oxidative stress and inflammation. Although the underlying mechanisms of milk proteins on cardiometabolic homeostasis remains to be elucidated, the most likely mechanism is to improve insulin resistance. The incorporation of meals enriched with dairy protein in the habitual diet may result in the beneficial effects on cardiometabolic health. Nevertheless, future well-designed, controlled studies are needed to investigate the relative effects of both casein and whey protein on BP, vascular function, glucose homeostasis and inflammation.

Functional properties and sensory testing of whey protein concentrate sweetened with rebaudioside A

ABSTRACT Objective: To develop a natural dietary product with functional benefits for diabetic patients. Whey protein concentrate was obtained through the separation membrane processes and sweetened with rebaudioside A. This product was submitted to sensory testing in humans and used to evaluate possible functional properties in male Wistar rats models with diabetesMellitus induced by streptozotocin. Methods: Two concentrates were produced. Only the second showed protein content of 74.3 and 17.3% of lactose was used as supplementation in induced diabetic rats. This concentrate was obtained from the concentration by reverse osmosis system (180 k Daltons), followed by nanofiltration in a 500 k Daltons membrane and spray drying at 5.0% solution of the first concentrate developed. The concentrate was sweetened with rebaudioside A (rebaudioside A 26 mg/100 g concentrate). All procedures were performed at the Center for Studies in Natural Products, at the Universidade Estadual de Maringá. Three experimental groups were established (n=6): two groups of diabetic animals, one control group and one supplemented group; and a control group of normal mice (non-diabetic). The supplemented group received concentrates sweetened with rebaudioside A in a dose of 100 mg/kg bw/day by an esophageal tube for 35 days. Fasting, the fed state and body weight were assessed weekly for all groups. At the end of the supplementation period, the following were analyzed: plasma parameters of glucose, total cholesterol, triglycerides and fructosamine; the serum levels of aspartate aminotransferase and alanine aminotransferase, water and food intake. Organs and tissues were removed and weighed to assess mass and anatomical changes. Results: The product presented 74% of proteins and 17% of lactose and showed satisfactory sensory testing by the addition of 26 mg of rebaudioside A/100 g concentrate. Supplementation of the product reduced hyperglycemia, plasma fructosamine levels, triglycerides and total cholesterol, and improved body weight gain of streptozotocin-induced diabetic rats. Conclusion: Whey protein concentrate with substantial content of protein (above 70%) and low lactose was obtained through the membrane separation processes. The addition of rebaudioside A at the concentration of 26 mg/100 g rebaudioside A proved to be as sweet as sucralose with satisfactory sensory testing, which indicates that this is a non-caloric natural sweetener that can replace artificial sweeteners. The product (whey protein concentrate sweetened with rebaudioside A) presented important functional properties and reduced the metabolic disorders caused by the syndrome.

Whey protein: The “whey” forward for treatment of type 2 diabetes?

A cost-effective nutritional approach to improve postprandial glycaemia is attractive considering the rising burden of diabetes throughout the world. Whey protein, a by-product of the cheese-making process, can be used to manipulate gut function in order to slow gastric emptying and stimulate incretin hormone secretion, thereby attenuating postprandial glycaemic excursions. The function of the gastrointestinal tract plays a pivotal role in glucose homeostasis, particularly during the postprandial period, and this review will discuss the mechanisms by which whey protein slows gastric emptying and stimulates release of gut peptides, including the incretins. Whey protein is also a rich source of amino acids, and these can directly stimulate beta cells to secrete insulin, which contributes to the reduction in postprandial glycaemia. Appetite is suppressed with consumption of whey, due to its effects on the gut-brain axis and the hypothalamus. These properties of whey protein suggest its potential in the management of type 2 diabetes. However, the optimal dose and timing of whey protein ingestion are yet to be defined, and studies are required to examine the long-term benefits of whey consumption for overall glycaemic control.

Emerging trends in nutraceutical applications of whey protein and its derivatives

The looming food insecurity demands the utilization of nutrient-rich residues from food industries as value-added products. Whey, a dairy industry waste has been characterized to be excellent nourishment with an array of bioactive components. Whey protein comprises 20 % of total milk protein and it is rich in branched and essential amino acids, functional peptides, antioxidants and immunoglobulins. It confers benefits against a wide range of metabolic diseases such as cardiovascular complications, hypertension, obesity, diabetes, cancer and phenylketonuria. The protein has been validated to boost recovery from resistance exercise-injuries, stimulate gut physiology and protect skin against detrimental radiations. Apart from health invigoration, whey protein has proved its suitability as fat replacer and emulsifier. Further, its edible and antimicrobial packaging potential renders its highly desirable in food as well as pharmaceutical sectors. Considering the enormous nutraceutical worth of whey protein, this review emphasizes on its established and emerging biological roles. Present and future scopes in food processing and dietary supplement formulation are discussed. Associated hurdles are identified and how technical advancement might augment its applications are explored. This review is expected to provide valuable insight on whey protein-fortified functional foods, associated technical hurdles and scopes of improvement.

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.

Dietary α-lactalbumin supplementation alleviates normocaloric western diet-induced glucose intolerance in Göttingen minipigs

OBJECTIVE

The pandemic of obesity in Western countries is mainly due to the high-fat, high-energy diet prevailing there. Obesity-associated metabolic disorders are the consequence of fat mass increase leading to altered adipokine secretion, hyperlipemia, oxidant stress, low-grade inflammation, and eventually glucose intolerance. Yet not all people consuming a Western diet become obese, and the question is raised whether these people are also at risk of developing metabolic disorders.

METHODS

Glucose tolerance, lipid profile, and oxidant and inflammation status were investigated longitudinally in lean Göttingen minipigs receiving for 16 weeks either a normal diet (ND), a Western diet (WD), or a Western diet supplemented with a whey protein isolate (WPI) rich in α-lactalbumin known to improve glucose tolerance. ND and WD were supplied isoenergetically.

RESULTS

Lean minipigs fed WD displayed glucose intolerance and altered lipid profile after 6 weeks of diet but no inflammation or oxidative stress. Supplementation with WPI alleviated glucose intolerance by improving insulin secretion, but not lipid profile.

CONCLUSIONS

Western diet consumption is deleterious for glucose tolerance even in the absence of fat mass accretion, and dyslipemia is a major determinant for this metabolic dysfunction. Stimulating insulin secretion with a WPI is an effective strategy to improve glucose tolerance.

Effects of dairy protein and fat on the metabolic syndrome and type 2 diabetes

The incidence of the metabolic syndrome (MetS) and type 2 diabetes (T2D) is increasing worldwide. Evidence supports a negative relationship between the consumption of dairy products and risk of MetS and T2D. Dairy proteins are known to have a directly beneficial effect on hypertension, dyslipidemia, and hyperglycemia, but a detailed understanding of the underlying mechanisms is missing. It has been confirmed by observations that the insulinotropic effect of dairy proteins is associated with the amino acid composition; in particular branched-chain amino acids (BCAA) seem to be of vital importance. Dairy protein-derived peptides may also contribute to the insulinotropic effect via dipeptidyl peptidase-4 (DPP-4) inhibitory activity, and may lower the blood pressure (BP). The lipid metabolism may be improved by whey protein (WP), which acts to reduce the postprandial triglyceride (TG) response. The effect of dairy fat is much more controversial because of the potentially harmful effect exerted by saturated fatty acid (SFA) on metabolic health. Recent observations suggest less adverse effects of SFA on metabolic health than previous assumed. However, little is known about dairy lipid fractions belonging to the groups of monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and phospholipids (PL). Dairy fat seems to act differently depending on the dairy product and the composition of macronutrients in the meal. Therefore, for a better understanding of the mechanisms behind the dairy protein and fat effect on MetS, we suggest that more human studies should be carried out to clarify the interactions of dairy protein and fat with macronutrients in the meal and other dairy components, such as micronutrients and microorganisms from fermented products.

Vitamin D and L-cysteine levels correlate positively with GSH and negatively with insulin resistance levels in the blood of type 2 diabetic patients

Background/Objectives:

Vitamin D, L-cysteine (LC) and glutathione (GSH) levels are lower in the blood of diabetic patients. This study examined the hypothesis that the levels of vitamin D and LC correlate with those of GSH in the blood of type 2 diabetic patients (T2D), and that vitamin D and LC upregulate glutamate–cysteine ligase (GCLC), which catalyzes GSH biosynthesis, in cultured monocytes.

Subjects/Methods:

Fasting blood was obtained after written informed consent from T2D (n=79) and healthy controls (n=22). U937 monocytes were pretreated with 1,25 (OH)₂ vitamin D (0–25 nM) or LC (0–500 μM) for 24 h and then exposed to control or high glucose (25 mM) for 4 h.

Results:

Plasma levels of vitamin D, LC, GSH and GCLC protein were significantly lower in T2D versus those in age-matched healthy controls. Multiple linear regression analyses and adjustment for body weight showed a significant positive correlation between plasma levels of vitamin D (r=0.26, P=0.05) and LC (r=0.81, P=0.001) and that of GSH, and between LC and vitamin D (r=0.27, P=0.045) levels. Plasma levels of GSH (r=−0.34, P=0.01) and LC (r=−0.33, r=0.01) showed a negative correlation with triglyceride levels. Vitamin D correlated inversely with HbA_1C (−0.30, P=0.01) and homeostatic model assessment insulin resistance (r=−0.31, P=0.03), which showed a significant positive correlation with triglycerides (r=0.44, P=0.001) in T2D. Cell culture studies demonstrate that supplementation with vitamin D and LC significantly increased GCLC expression and GSH formation in control and high-glucose-treated monocytes.

Conclusions:

This study suggests a positive relationship between the concentrations of the micronutrients vitamin D and LC and that of GSH. Some of the beneficial effects of vitamin D and LC supplementation may be mediated by an increase in the levels of GSH and a decrease in triglyceride levels in T2D patients.

The glycemic, insulinemic and plasma amino acid responses to equi-carbohydrate milk meals, a pilot- study of bovine and human milk

BACKGROUND

Dairy proteins, in particular the whey fraction, exert insulinogenic properties and facilitate glycemic regulation through a mechanism involving elevation of certain plasma amino acids, and stimulation of incretins. Human milk is rich in whey protein and has not been investigated in this respect.

METHOD

Nine healthy volunteers were served test meals consisting of human milk, bovine milk, reconstituted bovine whey- or casein protein in random order. All test meals contributed with 25 g intrinsic or added lactose, and a white wheat bread (WWB) meal was used as reference, providing 25 g starch. Post-prandial levels in plasma of glucose, insulin, incretins and amino acids were investigated at time intervals for up to 2 h.

RESULTS

All test meals elicited lower postprandial blood glucose responses, expressed as iAUC 0-120 min compared with the WWB (P < 0.05). The insulin response was increased following all test meals, although only significantly higher after whey. Plasma amino acids were correlated to insulin and incretin secretion (iAUC 0-60 min) (P ≤ 0.05). The lowered glycemia with the test meals (iAUC 0-90 min) was inversely correlated to GLP-1 (iAUC 0-30 min) (P ≤ 0.05).

CONCLUSION

This study shows that the glycemic response was significantly lower following all milk/milk protein based test meals, in comparison with WWB. The effect appears to originate from the protein fraction and early phase plasma amino acids and incretins were involved in the insulin secretion. Despite its lower protein content, the human milk was a potent GLP-1 secretagogue and showed insulinogenic properties similar to that seen with reconstituted bovine whey-protein, possibly due to the comparatively high proportion of whey in human milk.

Dietary whey protein lessens several risk factors for metabolic diseases: a review

Obesity and type 2 diabetes mellitus (DM) have grown in prevalence around the world, and recently, related diseases have been considered epidemic. Given the high cost of treatment of obesity/DM-associated diseases, strategies such as dietary manipulation have been widely studied; among them, the whey protein diet has reached popularity because it has been suggested as a strategy for the prevention and treatment of obesity and DM in both humans and animals. Among its main actions, the following activities stand out: reduction of serum glucose in healthy individuals, impaired glucose tolerance in DM and obese patients; reduction in body weight; maintenance of muscle mass; increases in the release of anorectic hormones such as cholecystokinin, leptin, and glucagon like-peptide 1 (GLP-1); and a decrease in the orexigenic hormone ghrelin. Furthermore, studies have shown that whey protein can also lead to reductions in blood pressure, inflammation, and oxidative stress.