Article

Effect of Premeal Consumption of Whey Protein and Its Hydrolysate on Food Intake and Postmeal Glycemia and Insulin Responses in Young Adults

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Abstract

Dairy protein ingestion before a meal reduces food intake and, when consumed with carbohydrate, reduces blood glucose. The objective was to describe the effect of whey protein (WP) or its hydrolysate (WPH) when consumed before a meal on food intake, pre- and postmeal satiety, and concentrations of blood glucose and insulin in healthy young adults. Two randomized crossover studies were conducted. WP (10-40 g) in 300 mL water was provided in experiment 1, and WP (5-40 g) and WPH (10 g) in 300 mL water were provided in experiment 2. At 30 min after consumption, the subjects were fed an ad libitum pizza meal (experiment 1) or a preset pizza meal (12 kcal/kg, experiment 2). Satiety, blood glucose, and insulin were measured at baseline and at intervals both before and after the meals. In experiment 1, 20-40 g WP suppressed food intake (P < 0.0001) and 10-40 g WP reduced postmeal blood glucose concentrations and the area under the curve (AUC) (P < 0.05). In experiment 2, 10-40 g WP, but not WPH, reduced postmeal blood glucose AUC and insulin AUC in a dose-dependent manner (P < 0.05). The ratio of cumulative blood glucose to insulin AUCs (0-170 min) was reduced by > or =10 g WP but not by 10 g WPH. WP consumed before a meal reduces food intake, postmeal blood glucose and insulin, and the ratio of cumulative blood glucose to insulin AUCs in a dose-dependent manner. Intact WP, but not WPH, contributes to blood glucose control by both insulin-dependent and insulin-independent mechanisms. This trial was registered at clinicaltrials.gov as NCT00988377 and NCT00988182.

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... high-CHO, low-glycaemic index and low-fat breakfasts are effective in optimising the insulin secretion and glycaemic response to lunch (15)(16)(17)(18) ), the efficacy of protein has received less research attention. Several studies have demonstrated that protein, specifically whey, consumed as a pre-load can elicit the secondmeal effect (19)(20)(21) . This has been attributed to augmented insulin secretion and insulin priming of the muscle and liver, alongside delayed gastric emptying of the second load (20,21) . ...
... Several studies have demonstrated that protein, specifically whey, consumed as a pre-load can elicit the secondmeal effect (19)(20)(21) . This has been attributed to augmented insulin secretion and insulin priming of the muscle and liver, alongside delayed gastric emptying of the second load (20,21) . Protein ingestion has also been linked to appetite suppression and a reduction in subsequent energy intake (4,20,22) , although other studies report no such effects (19,23) . ...
... This has been attributed to augmented insulin secretion and insulin priming of the muscle and liver, alongside delayed gastric emptying of the second load (20,21) . Protein ingestion has also been linked to appetite suppression and a reduction in subsequent energy intake (4,20,22) , although other studies report no such effects (19,23) . In addition, recent evidence suggests that a high-protein breakfast may be a more potent stimulator of the second-meal effect than a high-CHO breakfast (24,25) , although this possibility requires confirmation in young, normoglycaemic populations. ...
Article
Poor postprandial glucose control is a risk factor for multiple health conditions. The second-meal effect refers to the progressively improved glycaemic control with repeated feedings, an effect which is achievable with protein ingestion at the initial eating occasion. The most pronounced glycaemic response each day therefore typically occurs following breakfast, so this study investigated whether ingesting protein during the night could improve glucose control at the first meal of the day. In a randomised cross-over design, fifteen adults (7 males, 8 females; age, 22 ± 3 years; BMI, 24.0 ± 2.8 kg·m ⁻² ; fasting blood glucose, 4.9 ± 0.5 mmol·L ⁻¹ ) woke at 0400 ± 1 h to ingest 300 ml water with or without 63 g whey protein. Participants then completed a mixed-macronutrient meal tolerance test (1 g carbohydrate·kg body mass ⁻ 1, 563 ± 104 kcal,) 5 h 39 min following the nocturnal feeding. Nocturnal protein ingestion increased the glycaemic response (incremental area under curve) to breakfast by 43.5 ± 55.5 mmol•120 min•L ⁻¹ ( p =0.009, d =0.94). Consistent with this effect, individual peak blood glucose concentrations were 0.6 ± 1.0 mmol·L ⁻¹ higher following breakfast when protein had been ingested ( p =0.049, d =0.50). Immediately prior to breakfast, rates of lipid oxidation were 0.02 ± 0.03 g·min ⁻¹ higher ( p =0.045) in the protein condition, followed by an elevated postprandial energy expenditure (0.09 ± 0.12 kcal·min ⁻¹ , p =0.018). Postprandial appetite and energy intake were similar between conditions. This study reveals a paradoxical second-meal phenomenon whereby nocturnal whey protein feeding impaired subsequent glucose tolerance, whilst increasing postprandial energy expenditure.
... Il numero di studi sperimentali a supporto di questo approccio nutrizionale è in rapida crescita (26). Tali studi sono però di difficile reperimento a causa della molteplicità delle parole chiave utilizzate dai diversi gruppi di ricerca per definire strategie dietetiche simili, quali ad esempio premeal consumption (27)(28) o nutrient preload (22,(29)(30)(31)(32) / sequence (33-34) / order (35). A questo si aggiunge l'estrema eterogeneità della qualità, quantità, tempistiche e modi di somministrazione dei singoli macronutrienti che contribuisce alla varietà degli effetti ipoglicemizzanti osservati e rende difficile l'interpretazione e il confronto dei diversi studi (36). ...
... proteine determina un incremento di 2-3 volte del rilascio di insulina stimolato da un successivo carico di carboidrati in individui con DT2, un dato confermato in altre popolazioni di soggetti diabetici e non diabetici (28,48,53). L'effetto insulinotropico delle proteine è tempo-e dose-dipendente (22,27) ed è verosimilmente secondario ad interazioni sia dirette che incretino-mediate degli aminoacidi con le β-cellule (54-58) (Fig. 3). Numerose evidenze suggeriscono infatti che l'incremento degli aminoacidi in circolo in seguito alla digestione delle proteine sia in grado di "pre-allertare" la β-cellula, producendo un rilascio di insulina più rapido e di maggiore entità in risposta al glucosio (59)(60). ...
... Le proteine del siero del latte (whey proteins) sono particolarmente ricche in leucina ed amminoacidi ramificati; questo, unito ad un rapido assorbimento ed una pronta biodisponibilità, le rende particolarmente efficaci nel potenziare la secrezione insulinica (61)(62). È interessante notare che questo effetto insulinotropico si verifica anche per dosi modeste di proteine assunte: 10 g di proteine del siero del latte, intere od idrossilate, sono sufficienti ad incrementare sensibilmente i livelli di insulina plasmatica (27). Malgrado alcuni aminoacidi possiedano una più spiccata attività insulinotropica rispetto ad altri, l'assunzione di proteine intere o la combinazione di più amminoacidi diversi è generalmente in grado di esercitare un effetto maggiore sulla β-cellula rispetto alla somministrazione di singoli amminoacidi separatamente (63). ...
... The incremental AUC for glucose decreased in a dose-dependent manner with the highest dose of whey protein supplement having a significantly greater effect than lower doses on postprandial hyperglycemia from a glucose drink [85]. Similarly, increasing doses of whey protein (10-40 g) pre-meal reduced post-meal blood glucose and insulin AUC in a dose-dependent manner [86]. The combination of whey protein and carbohydrate intake results in increased plasma insulin and reduced plasma glucose concentrations compared with those consuming carbohydrate alone [87]. ...
... The beneficial effects of milk, as seen in cross-sectional and epidemiological studies [14][15][16][17][74][75][76][77][91][92][93][94], are supported by clinical trials and postprandial intervention studies [20,21,[78][79][80][81][82][83][84]100]. Regardless of the outcome, nearly all research studies attribute the favorable metabolic effects of dairy, at least in part, to the insulinotropic effects of milk proteins [27,[85][86][87][88]101,103]. Indeed, compared with other protein sources, milk demonstrates a larger insulin response up to 4 h post-meal [19]. ...
... Whey protein reduces acute postprandial glucose response in healthy adults and those with type 2 diabetes [27,85,86,127,128]. Additionally, insulin-independent reduction in blood glucose is seen with whey protein consumption in healthy adults [128]. ...
Article
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Postprandial plasma glucose and triglyceride concentrations are predictive of relative cardiovascular disease (CVD) risk, and the pathogenesis of both insulin resistance and atherosclerosis has been attributed to acute states of hyperglycemia and hypertriglyceridemia. Postprandial lipemia and hyperglycemia suppress vascular reactivity and induce endothelial dysfunction. Epidemiological studies suggest that chronically-high consumption of milk and milk products is associated with a reduced risk of type 2 diabetes, metabolic syndrome, and CVD. The addition of dairy products to meals high in carbohydrates and fat may lessen these risks through reductions in postprandial glucose and triglyceride responses. Purported mechanisms include dairy proteins and bioactive compounds, which may explain the inverse relationship between dairy consumption and cardiometabolic diseases. The current review evaluates the available literature describing the relationships between metabolic dysfunction, postprandial metabolism, and vascular dysfunction and discusses the potential role of milk and dairy products in attenuating these impairments.
... Several lines of evidence demonstrates the capacity of WP to regulate PPG in patient (19, 31-34, 42, 43) and non-patient (44)(45)(46) populations. A summary of acute randomized-control trials utilizing mealtime WP to control PPG in individuals with T2D is presented in Table 1. ...
... Yet, a significant caveat to this approach is the timing of the pre-load and commencement of the meal. For instance, a wealth of studies have presented WP 30 min before the nutrient challenge (19,31,33,34,44,45), which is unlikely to replicate free-living behaviors. Indeed, adherence to prandial medications, which are prescribed to align with eating occasions, can fall short due to patient forgetfulness and the burden of having to plan ahead (49,50). ...
... Evidence to date has primarily presented unrealistically large WP doses (25-55 g), entailing a significant caloric load with a large financial cost associated (19,31,33,48). Indeed, the glucose-lowering efficacy of WP is reported to be dose-dependent (44). However, when accounting for the energy content of WP pre-loads (20-70 g), despite reducing energy intake at ad libitum meals compared to a control treatment, cumulative energy intake is similar (44,53). ...
Article
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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.
... Recent investigations have implemented whey protein as a potential treatment for the management of IR [6,7]. Whey protein augments insulin secretion through an increase of the incretin hormones in people with type 2 diabetes [8], while subsequently decreasing blood glucose concentrations in both healthy [9], and type 2 diabetes [10]. ...
... Recent literature has suggested smaller doses of whey protein such as 15 g for those with type 2 diabetes [7] and 20 g for obese males [6], consumed prior to meal ingestion can reduce postprandial glucose. In healthy individuals, there is a dose dependent postprandial increase in insulin, with a subsequent decrease in glucose following whey protein ingestion of 5-20 g [11], 10-40 g [9], and 10-20 g [12]. However, it is unknown if there is a similar dose effect of whey protein in individuals with IR. ...
... The current study found that whey protein doses of 20 g and 30 g administered 30 min prior to an OGTT resulted in a concomitant rise in plasma insulin complete i AUC; however, plasma glucose was unaffected. Previous literature suggests 40 g and 50 g of whey protein can provide glycemic benefit in individuals with IR [9,10]. Contradictory to previous studies examining lower doses, the results of the current study suggest that 20 g and 30 g of whey protein may not be beneficial in individuals with IR. ...
Article
Whey protein coupled with a glucose challenge increases insulin secretion and may decrease glucose responses in people with pre-diabetes and type 2 diabetes. These responses may be attributed to whey protein's effect on the incretins glucagon-like peptide-1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP). The purpose of this study was to examine the effect of various doses of whey protein on postprandial glycemic control and incretin responses. Participants with insulin resistance (n=9, mean ± SD; age: 64.3 + 8.1 yrs; BMI: 29.4 + 6.0 kg/m 2 ; fasting plasma glucose: 6.9 + 1.2 mmol/l; HbA1c: 6.4 + 0.6%) completed three randomized treatments. Treatment 1 included 250 ml water + 20 g whey protein (T 1), and treatment 2 included 250 ml water + 30 g whey protein (T 2). The control treatment included 250 ml water (CON). Each treatment was followed by a 50 g oral glucose tolerance test. Incremental area under the curve (i AUC) for insulin increased from CON to T 1 (P<0.01, 45.5%), CON to T 2 (P<0.01, 61.0%), and T 1 to T 2 (P<0.01, 28.5%), with a significant decrease in postprandial AUC for glucose with T 2 (P=0.04,-41.2%). Neither GIP nor GLP-1 i AUC increased with T 1 or T 2 compared to CON. However, postprandial glucose i AUC was significantly reduced for T 2 compared to CON (P=0.04,-41.2%). There was a dose effect of whey protein on plasma insulin with a significant decrease in postprandial glucose i AUC following T 2. Thirty grams of a whey protein preload may be adequate to provide postprandial glycemic improvements in the disease management of type 2 diabetes or pre-diabetes
... Participants were reached through general announcements made in classrooms. The sample size required was based on previous short-term food intake studies with a power of 0.80 and an alpha of <0.05 (Akhavan et al. 2010, Panahi et al. 2013. For this research, the permissions were obtained from Istanbul Medipol University Non-Invasive Clinical Research Ethics Committee (No: 10840098-604.01.01-E.14959). ...
... The protocol and procedures are similar to those reported in previous studies (Akhavan et al. 2010, Panahi et al. 2013. Participants were asked to arrive at the same time and on the same day of the week for all sessions. ...
Article
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Fiber content of a meal is distinctly effective in appetite. There are studies that draw attention to the effects of protein and fiber combined meals on short-term satiety and food intake. This study was performed to examine the effects of different fiber sources in a protein-containing meal during satiety and hunger. The study was carried out once a week on the same day and for three-week duration, with total of 17 randomly selected participants with ages between 18 and 24 years. The test foods containing different vegetable fiber sources (chickpeas and oats) were given to the participants every week as isocaloric, which have been the control food for a week. The satiety status was evaluated by visual analog scale (VAS) for total of five times as immediately before the test food consumption and at 30, 60, 90 and 120 minutes after consumption. Fasting and postprandial blood glucose levels were measured. A 24-hour retrospective food consumption record was obtained the next day. There was no statistically significant difference among the VAS results of the three groups, which were given chickpea + yoghurt (CY), oat + yoghurt (OY), and yoghurt (Y) as control (p> 0.05). No significant difference was observed in ad libitum food intake after the test food and daily energy intake determined by 24-hour food consumption records (p> 0.05). However, the energy and macronutrient intake of the OY group at the ad libitum lunch and the rest of the day were significantly lower than that of CY. The difference between blood glucose levels during hunger and satiety states of CY group was found significant (p <0.05). Collectively, the VAS findings revealed that consumption of fiber-enriched meal has a significant effect on short-term satiety, daily energy intake and blood glucose level control compared to a protein-only meal, however no significant difference was observed between the types of fiber consumed. Registered under ClinicalTrials.gov Identifier no. NCT 04601025.
... Pre-meals of protein administered prior to a meal have shown promising results on the postprandial blood glucose in non-pregnant healthy individuals and individuals with T2DM [60,61]. In a RCT of 52 women with GDM receiving either 8.5 g of casein hydrolysate (n = 26) or placebo (n = 26) prior to breakfast and dinner for eight days, the average blood glucose was decreased in the casein group [62]. ...
... Milk protein consists of 80% casein and 20% whey. Pre-meal whey protein has shown promising results with lower postprandial blood glucose in both healthy subjects, subjects with metabolic syndrome, and T2DM [60,61,63,64]. T2DM and GDM share similarities in their pathophysiology and, hence, women with GDM may display the same beneficial effect of whey pre-meals on blood glucose. ...
Article
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Gestational diabetes mellitus (GDM) among pregnant women increases the risk of both short-term and long-term complications, such as birth complications, babies large for gestational age (LGA), and type 2 diabetes in both mother and offspring. Lifestyle changes are essential in the management of GDM. In this review, we seek to provide an overview of the lifestyle changes which can be recommended in the management of GDM. The diet recommended for women with GDM should contain sufficient macronutrients and micronutrients to support the growth of the foetus and, at the same time, limit postprandial glucose excursions and encourage appropriate maternal gestational weight gain. Blood glucose excursions and hyperglycaemic episodes depend on carbohydrate-intake. Therefore, nutritional counselling should focus on the type, amount, and distribution of carbohydrates in the diet. Further, physical activity has beneficial effects on glucose and insulin levels and it can contribute to a better glycaemic control.
... Pre-meals of whey protein have shown promising effects on the subsequent glucose trajectories in both healthy participants and patients with type 2 diabetes mellitus (T2DM) [1,2]. Whey given 15-30 min before a meal mediates a rise in insulin concentration and results in lower postprandial blood glucose concentrations [1,3]. ...
... We did not include a control condition (e.g., tap-water) in the OGTT experiment because the primary aim of the study was to compare BLG and WPI. Pre-meals of whey have, in many previous studies, already proven effective in lowering glucose concentrations [2,3,21,28], but direct comparisons to other proteins are sparse. ...
Article
Full-text available
Whey protein is an insulinotropic fraction of dairy that reduces postprandial glucose levels in patients with type 2 diabetes mellitus (T2DM). We have recently shown that β-lactoglobulin (BLG), the largest protein fraction of whey, elevates insulin concentrations compared with iso-nitrogenous whey protein isolate (WPI) in healthy individuals. We therefore hypothesized that BLG pre-meals would lower glucose levels compared with WPI in patients with T2DM. We investigated 16 participants with T2DM using a randomized double-blinded cross-over design with two pre-meal interventions, (i) 25 g BLG and (ii) 25 g WPI prior to an oral glucose tolerance test (OGTT), followed by four days of continuous glucose monitoring (CGM) at home. BLG increased concentrations of insulin with 10%, glucagon with 20%, and glucose with 10% compared with WPI after the OGTT (all p < 0.05). Both BLG and WPI reduced the interstitial fluid (ISF) glucose concentrations (using CGM) with 2 mM and lowered glycemic variability with 10–15%, compared with tap-water (p < 0.05), and WPI lowered the ISF glucose with 0.5 mM compared with BLG from 120 min and onwards (p < 0.05). In conclusion, BLG pre-meals resulted in higher insulin, glucagon, and glucose concentrations compared with WPI in participants with T2DM. Pre-meal servings of WPI remains the most potent protein in terms of lowering postprandial glucose excursions.
... Yet, its role in improving glucose metabolism as a supplement is not well described in controlled clinical studies, most of which were performed in patients with T2D [40][41][42][43]. Milk and whey protein are known to stimulate insulin [44][45][46][47][48][49][50] and thus reduce the postprandial glucose response to a glucose solution [45,[47][48][49][50][51]. However, in the case of single amino acids, the insulinogenic effect is not attributable to all amino acids [52][53][54][55] and requires higher doses than the ones used here [52,53,[56][57][58]. ...
... Yet, its role in improving glucose metabolism as a supplement is not well described in controlled clinical studies, most of which were performed in patients with T2D [40][41][42][43]. Milk and whey protein are known to stimulate insulin [44][45][46][47][48][49][50] and thus reduce the postprandial glucose response to a glucose solution [45,[47][48][49][50][51]. However, in the case of single amino acids, the insulinogenic effect is not attributable to all amino acids [52][53][54][55] and requires higher doses than the ones used here [52,53,[56][57][58]. ...
Article
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High postprandial blood glucose levels are associated with increased mortality, cardiovascular events and development of diabetes in the general population. Interventions targeting postprandial glucose have been shown to prevent both cardiovascular events and diabetes. This study evaluates the efficacy and safety of a novel nutritional supplement targeting postprandial glucose excursions in non-diabetic adults. Sixty overweight healthy male and female participants were recruited at two centers and randomized in a double-blind, placebo-controlled, crossover design. The supplement, a water-based drink containing 2.6g of amino acids (L-Leucine, L-Threonine, L-Lysine Monohydrochloride, L-Isoleucine, L-Valine) and 250 mcg of chromium picolinate, was consumed with a standardized carbohydrate-rich meal. The primary endpoint was the incremental area under the curve (iAUC) for venous blood glucose from 0 to 120 minutes. Secondary endpoints included glucose iAUC 0-180 minutes and the maximum glucose concentration (Cmax), for both venous and capillary blood glucose. In the intention-to-treat-analysis (n = 60) the supplement resulted in a decreased venous blood glucose iAUC0-120min compared to placebo, mean (SE) of 68.7 (6.6) versus 52.2 (6.8) respectively, a difference of -16.5 mmol/L•min (95% CI -3.1 to -30.0, p = 0.017). The Cmax for venous blood glucose for the supplement and placebo were 6.45 (0.12) versus 6.10 (
... However, the dose of amino acids given seems important, as the intake of 5 g of whey was found to be insufficient to induce insulin after 15 or 30 min [38]. It is therefore possible that the protein dose given in our study (5.2 g) was insufficient to induce the secretion of insulin. ...
... It is therefore possible that the protein dose given in our study (5.2 g) was insufficient to induce the secretion of insulin. Cellulose, used as an excipient in the capsules, has been reported to modulate postprandial glycaemia and insulinaemia [38][39][40]; however, the total amount of cellulose from the 30 capsules (2.7-7.2 g) did not exceed the level believed to be needed to modify the glucose and insulin response [40]. Thus, our study appears well-suited to study the systemic effects of amino acids from two different protein sources without interference from insulin. ...
Article
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Fish is considered an important part of a healthy diet, in part due to the content of long chain omega-3 fatty acids. However, both lean and fatty fish have beneficial health effects, suggesting that micronutrients and proteins may play a role. In a randomised, controlled, cross-over trial, five healthy male participants consumed 5.2 g of protein from either salmon fishmeal or whey. Blood samples were taken before and 30 and 60 min after intake. The concentration of glucose, lipids, hormones and metabolites, including 28 different amino acids and derivatives, were measured in serum or plasma. Cultured HepG2 cells were incubated with or without serum from the participants, and transcriptomic profiling was performed using RNA sequencing. The ingestion of both salmon fishmeal and whey reduced the glucose and triglyceride levels in serum. Protein intake, independent of the source, increased the concentration of 22 amino acids and derivatives in serum. Fishmeal increased the concentration of arginine, methionine, serine, glycine, cystathionine and 2-aminobutyric acid more than whey did. Incubation with postprandial serum resulted in large transcriptomic alterations in serum-fasted HepG2 cells, with the differential expression of >4500 protein coding genes. However, when comparing cells cultivated in fasting serum to postprandial serum after the ingestion of fishmeal and whey, we did not detect any differentially regulated genes, neither with respect to the protein source nor with respect to the time after the meal. The comparable nutrigenomic effects of fishmeal and whey do not change the relevance of fish by-products as an alternative food source.
... These improvements in postprandial glycemia are partially due to whey protein's ability to enhance insulin secretion [21][22][23] . Whey protein also stimulates the secretion of incretin hormones, glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide (GIP), which have been demonstrated to potentiate insulin secretion 21,[24][25][26] . ...
... In addition to timing, the dose or amount of whey protein consumed appears to in uence the magnitude of its effects on blood glucose 21 . Several studies have demonstrated positive effects on insulin and glucose responses with higher doses (20-55 g) of whey protein 19,23,27,28 . Our lab has previously examined how differences in the dose of whey protein can in uence glycemia. ...
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Background: Both aerobic exercise and whey protein can improve glucose regulation. The purpose of this study was to investigate how a single bout of vigorous-intensity aerobic exercise and whey protein, independently, as well as when combined, influence glycemia during an oral glucose tolerance test in sedentary, young men. Methods: Healthy males ( n = 11) completed four randomized trials: no exercise/no whey protein (R); exercise (EX; walking at 70% VO 2max for 60 min); 50 g of whey protein (W); and exercise combined with 50 g of whey protein (EXW). Each trial included a 75 g oral glucose tolerance test (OGTT) that was completed after an overnight fast, and blood samples were collected over a two-hour period during the OGTT. For EX and EXW, the exercise bout was performed the evening before the OGTT. Additionally, for W and EXW, the 50 g of whey protein was consumed as a preload 30 minutes prior to the OGTT. Plasma samples were analyzed for glucose, insulin, C-peptide, glucagon, gastric inhibitory peptide (GIP) and glucagon like peptide 1 (GLP-1), and postprandial incremental area under the curve (iAUC) was calculated for each. Results: Glucose iAUC was reduced during W (-32.9 ± 22.3 mmol/L) compared to R (122.7 ± 29.8 mmol/L; p < 0.01) and EX (154.3 ± 29.2 mmol/L; p < 0.01). Similarly, glucose iAUC was reduced for EXW (17.4 ± 28.9 mmol/L) compared to R and EX ( p < 0.01 for both). There were no differences in iAUC for insulin, C-peptide, GIP, GLP-1, and glucagon between the four trials. Insulin, C-peptide, glucagon, GIP, and GLP-1 were elevated during the whey protein preload period for W and EXW compared to EX and R ( p < 0.01). There were no differences for insulin, C-peptide, glucagon, GIP, or GLP-1 between trials for the remaining duration of the OGTT. Conclusions: Glucose responses during an oral glucose tolerance test were improved for W compared to EX. There were no additional improvements in glucose responses when vigorous-intensity aerobic exercise was combined with whey protein (EXW).
... A sample size of 12 was determined to be sufficient to show a treatment effect of 10% on blood glucose, the primary outcome measure, and on insulin, GLP-1, and ghrelin with a power of 0.80 and an α of <0.05, based on previous studies (27,28). A sample size of 28 was determined for a within-subject design in each age group, based on an earlier study (29), to be sufficient to detect a treatment effect of 100 kcal on food intake and a 10% change in subjective appetite with a power of 0.80 and an α of <0.05. ...
... The lack of control for the macronutrient and energy content of treatments may be seen as a limitation of the study design. However, many studies examining the role of dairy macronutrients and energy content on PPG and appetite have already shown that protein and energy are the primary factors affecting short-term appetite and metabolic effects of dairy products (13,16,(27)(28)(29). Similarly, the greater suppression in appetite and mealtime food intake in females after consuming dairy products was consistent with their higher treatment caloric intake per kilogram of body weight and consistent with a previous report comparing responses between males and females after a single serving of dairy (24). ...
Article
Background Dairy consumption reduces postprandial glycemia and appetite when consumed with carbohydrates. Objectives The objective was to test the effects of frequently consumed dairy products, age, and sex on glycemia, appetite, and food intake. Methods In a randomized, unblinded, crossover design, 30 older [60–70 y; BMI (kg/m2): 18.5–29.9] and 28 young (20–30 y; BMI: 18.5–24.9) adults consumed 500 mL of a calorie-free control (water), skim milk and whole milk, 350 g Greek yogurt, and 60 g cheddar cheese. Food intake at an ad libitum meal was measured 120 min later. Glycemia, appetite, and gastric hormone responses were measured premeal (15–120 min), within-meal (120–140 min), and postmeal (140–170 min). Effects of treatment, age, and sex and their interactions were analyzed using ANOVA followed by Tukey's post hoc test. Results All forms of dairy, compared with water, decreased postmeal glycemia, premeal appetite, and meal intake (P < 0.0001). Premeal glucose, insulin, and glucagon-like peptide 1 increased, and ghrelin decreased, but effects of dairy differed with age and sex. Older adults had 10% higher pre- and postmeal glucose (P < 0.01). Premeal appetite suppression per 100 kcal of treatments was more after yogurt than other dairy, but overall appetite suppression was less in older adults than in young adults and in males than in females (P < 0.05). Pizza intake was reduced by 175 kcal after yogurt and cheese and by 82 kcal after milks compared to water (P < 0.001). Mealtime reduction for treatment calories averaged 62% after yogurt and cheese but was less at 33% after milks (P < 0.05). Compensation was less in older (33%) than in young (63%) adults (P < 0.03). Conclusions Dairy products consumed in usual forms before a meal stimulate metabolic responses leading to reduced premeal appetite, later food intake, and postmeal glycemia, but their effects differ in magnitude and with the sex and age of adults.
... Scientific evidence shows that WP reduce dietary intake in many experimental models [25,26] so the use of WP as a supplement is a useful indication for increasing weight loss [27]. In an animal model using obese rats (dietinduced obesity), WP reduced dietary intake, where milk proteins were more active than casein or WP alone, to decrease weight gain [14]; in the animal model of rats whose obesity is diet-induced, WP compared to casein, associated with high calcium levels, were able to decrease body weight gain, while cumulative dietary intake showed no differences [28]; in another animal model of dietinduced obesity in rats, WP showed greater efficacy than red meat in reducing weight gain and improving insulin sensitivity [29]. ...
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Background/AimsWhey proteins (WP), obtained from milk after casein precipitation, represent a heterogeneous group of proteins. WP are reported to inhibit food intake in diet-induced experimental obesity; WP have been proposed as adjuvant therapy in oxidative stress-correlated pathologies. This work evaluates the effects of WP in comparison with casein, as a source of alimentary proteins, on food intake, weight growth and some indexes of oxidative equilibrium in Zucker Rats, genetically prone to obesity.Methods We monitored food intake and weight of Zucker Rats during the experiment, and some markers of oxidative equilibrium.ResultsWP induced significant decrease of food intake in comparison to casein (WP 80.41 ± 1.069 ml/day; CAS: 88.95 ± 1.084 ml/day; p < 0.0005). Body weight growth was slightly reduced, and the difference was just significant (WP 128.2 ± 6.56 g/day; CAS 145.2 ± 3.29 g/day; p = 0.049), while plasma HNE level was significantly lower in WP than in CAS (WP 41.2 ± 6.3 vs CAS 69.61 ± 4.69 pmol/ml, p = 0.007). Mild amelioration of oxidative equilibrium was indicated by a slight increase of total glutathione both in the liver and in the blood and a significant decrease of plasma 4-hydroxynonenal in the group receiving WP.Conclusions The effect of WP on food intake and weight growth in Zucker Rats is particularly noteworthy since the nature of their predisposition to obesity is genetic; the possible parallel amelioration of the oxidative balance may constitute a further advantage of WP since oxidative stress is believed to be interwoven to obesity, metabolic syndrome and their complications.
... Energy restriction contributes to the improvement of insulin resistance [77]. Experimental studies showed that milk proteins including WP lead to a reduction in short-term appetite and increase in satiety [78,79]; it seems that these effects of WP are mediated by gut hormones, particularly by the stimulation of cholecystokinin (CCK), peptide tyrosine tyrosine (PYY), and GLP-1 [80,81], as well as by ghrelin suppression [82]. In addition, amino acids liberated from WP digestion may suppress appetite [83,84] probably via the gut-brain axis and the direct effect at the hypothalamus [85]. ...
... Among the three protein fractions described above, whey accounts for approximately 13∼20% of the total proteins in sheep milk and is generally regarded as having measurable effects on health outcomes such as immunomodulatory, antimicrobial properties, acute inflammatory response, complement activation and innate immune response (Hernández-Ledesma, Ramos & Gómez-Ruiz, 2011;Ha et al., 2015). In addition, the natural digestion of sheep whey proteins in the gastrointestinal tract can generate peptides with a variety of bioactivities, for instance, antihypertensive, opioid, antibacterial, antioxidant, and immunomodulatory activities (Recio & Visser, 2000;Tina et al., 2010). The proteome of cow and sheep whey has attracted extensive research. ...
Article
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Background Ovine milk is a rich source of bioactive proteins that supports the early growth and development of the newborn lambs. A large number of researches had targeted to the identification of ovine milk fat globule membrane proteins (MFGMPs), caseins (CNs), mastitis milk proteins in past years, but the dynamic change tendency of milk whey proteins during postnatal development has received limited attention. This research aimed to investigate the dynamic changes of ovine milk whey proteins after delivery, and explore the functions of whey proteins on early development of the newborns. Methods In this research, Hu sheep milk samples were collected from six individuals by manual milking manner, at 0 d, 3 d, 7 d, 14 d, 28 d and 56 d after delivery, respectively. The milk whey proteins were identified and quantified by the isobaric tag for relative and absolute quantification (iTRAQ) coupled with liquid chromatography (LC)-electrospray ionization (ESI) tandem MS (MS/MS) methods. In addition, biological functions of differentially expressed proteins (DEPs) were annotated by Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Results A total of 310 proteins were identified , of which 121 were differentially expressed. In detail, 30 (10 up-regulated and 20 down-regulated), 22 (11 up-regulated and 11 down-regulated), 11 (four up-regulated and seven down-regulated), 11 (eight up-regulated and three down-regulated), 10 (six up-regulated and four down-regulated) DEPs were identified in 3 d vs. 0 d, 7 d vs. 3 d, 14 d vs. 7 d, 28 d vs. 14 d, 56 d vs. 28 d comparison groups, respectively. The GO annotation analysis revealed that biological process principally involved metabolic and biological regulation, the major cellular location were organelle, cell and extracellular region, and the mainly molecular function were binding and catalytic activity. Circadian rhythm, fatty acid biosynthesis and African trypanosomiasis were enriched by KEGG annotation analysis. Conclusion The study reveals a comprehensive understanding of Hu sheep milk proteome, suggesting whey proteins change dramatically in early development of newborn lambs, which provide a potential guidance for early weaning of lambs.
... As shown in previous correlations among hormone responses to consumption of these same treatments, GLP-1 and BG were negatively correlated (12). It has been shown that whey protein ingestion increases GLP-1 (16,25,26) and delays gastric emptying (16,27) in association with decreases in BG. However, post-lunch GLP-1 was not affected by the milks and cereal, nor did it associate with any of the plasma AA groups. ...
Article
Background: Increasing the total protein content and reducing the casein to whey ratio in milks consumed with breakfast cereal reduce postprandial blood glucose (BG). Objectives: We aimed to explore associations between plasma amino acids (AAs), BG, and glucoregulatory hormones. Methods: In this repeated-measures design, 12 healthy adults consumed cereal (58 g) and milks (250 mL) with 3.1 wt% or high 9.3 wt% protein concentrations and with casein to whey ratios of either 80:20 or 40:60. Blood was collected at 0, 30, 60, 120, 140, 170, and 200 min for measurement of the primary outcome, BG, and for the exploratory outcomes such as plasma AA, gastric emptying, insulin (INS), and glucoregulatory hormones. Measures were made prior to and after an ad libitum lunch at 120 min. Exploratory correlations were conducted to determine associations between outcomes. Results: Pre-lunch plasma AA groups [total (TAA), essential (EAA), BCAA, and nonessential (NEAA)] were higher after 9.3 wt% than 3.1 wt% milks by 12.7%, 21.4%, 20.9%, and 7.6%, respectively (P ≤ 0.05), while post-lunch AA groups were higher by 10.9%, 19.8%, 18.8%, and 6.0%, respectively (P ≤ 0.05). Except for NEAA, pre-lunch AAs were higher after 40:60 than 80:20 ratio milks by 4.5%, 8.3%, and 9.3% (P ≤ 0.05). When pooled by all treatments, pre-lunch AA groups associated negatively with BG (r/ρ ≥ -0.45, P ≤ 0.05), but post-lunch only TAA and NEAA correlated (r ≥ -0.37, P < 0.05). Pre-lunch BG was inversely associated with Leu, Ile, Lys, Met, Thr, Cys-Cys, Asn, and Gln (r/ρ ≥ -0.46, P ≤ 0.05), but post-lunch, only with Thr, Ala, and Gly (r ≥ -0.50, P ≤ 0.05). Pre-lunch associations between AA groups and INS were not found. Conclusions: Protein concentration and the ratio of casein to whey in milks consumed at breakfast with cereal affect plasma AA concentrations and their associations with decreased BG. The decrease in BG could be explained by INS-independent mechanisms. This trial was registered at www.clinicaltrials.gov as NCT02471092.
... Energy restriction contributes to the improvement of insulin resistance [77]. Experimental studies showed that milk proteins including WP lead to a reduction in short-term appetite and increase in satiety [78,79]; it seems that these effects of WP are mediated by gut hormones, particularly by the stimulation of cholecystokinin (CCK), peptide tyrosine tyrosine (PYY), and GLP-1 [80,81], as well as by ghrelin suppression [82]. In addition, amino acids liberated from WP digestion may suppress appetite [83,84] probably via the gut-brain axis and the direct effect at the hypothalamus [85]. ...
Article
Background/aims: Some studies showed that dietary factors such as whey protein (WP) are effective on glycemic regulation. Due to the current controversy about WP effects and mechanisms of its action on glycemic control, we conducted this systematic review to shed light on the subject. Methods: Web of Science, Medline (Pubmed), and Scopus online databases were searched from 2012 up to February 2022 using the following keywords: "whey protein" and "glycemic control"/"glycemia"/"glucose"/"insulin". The search included original English articles, human clinical trials with WP supplementation and measurement of glucose or insulin as an outcome, studies on healthy individuals/patients with diabetes mellitus (DM)/impaired fasting glucose (IFG). Results: Title/abstract of 1991 studies were reviewed. After excluding studies due to inappropriate full title and duplication, and exercising inclusion criteria, 58 studies were reviewed in detail. Ample evidence showed that WP decreased postprandial glucose incremental area under the curve (iAUC) and increased iAUCs of insulin and incretin hormones. WP affects glycemic control mainly through stimulating insulin and incretins secretion, slowing gastric emptying, and appetite suppression. Conclusion: Although most of the recent evidence showed beneficial effects of WP supplementation on glycemic response, further long-term clinical trials are required which assess the long-term impact of WP supplementation and its exact mechanisms.
... These effects have been observed in T2D and nondiabetic subjects [16]. It was reported that the glucose-lowering effect of protein preload was dose-dependent [17]. Several studies have been conducted to investigate the effects of preloading fats. ...
Article
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While adjustment of total energy and nutritional balance is critically important, meal sequence, a relatively simple method of correcting postprandial hyperglycemia, is becoming established as a practical dietary approach for prevention and management of diabetes and obesity. Meal sequence, i.e., consumption of protein and/or fat before carbohydrate, promotes secretion of glucagon-like peptide-1 (GLP-1) from the gut and ameliorates secretions of insulin and glucagon and delays gastric emptying, thereby improving postprandial glucose excursion. GLP-1 is known to suppress appetite by acting on the hypothalamus via the afferent vagus nerve. Thus, enhancement of GLP-1 secretion by meal sequence is expected to reduce body weight. Importantly, consumption of a diet rich in saturated fatty acids such as meat dishes before carbohydrate increases secretions of not only GLP-1 but also glucose-dependent insulinotropic polypeptide (GIP), which promotes energy storage in adipose tissue and may lead to weight gain in the long term. Dietary fiber intake before carbohydrate intake significantly reduces postprandial glucose elevation and may have a weight loss effect, but this dietary strategy does not enhance the secretion of GLP-1. Thus, it is suggested that their combination may have additive effects on postprandial glucose excursion and body weight. Indeed, results of some clinical research supports the idea that ingesting dietary fiber together with meal sequence of protein and/or fat before carbohydrate benefits metabolic conditions of individuals with diabetes and obesity.
... Plusieurs études épidémiologiques ont rapporté une corrélation négative entre la consommation régulière de lait et l'adiposité chez l'adulte [63,64]. Une consommation importante de produits laitiers a, également, été associées à une faible prévalence d'IR et à un moindre risque de DT2 et de MCV, chez l'adulte en surpoids [53,65,66]. ...
Article
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Since several years, dairy products have been at the heart of nutritional deba-tes. High-fat dairy products can aggravate dyslipidemia and the consumption of satura-ted, and trans fats is associated with an increased cardiovascular diseases risk. In this re-gard, current dietary guidelines recommend a low fat content, and a significant reduc-tion in trans fatty acid intake. However, recent controversial epidemiological studies show that high-fat dairy products consumption may reduce diabetes, metabolic syndro-me, and the risk of cardiovascular diseases. This dairy paradox has led to a dietary guidelines re-evaluation.
... Proteins, particularly whey protein, when administered intraduodenally or consumed 30 min before a meal, reduce energy intake and postprandial blood glucose, at least in part, by slowing gastric emptying and stimulating hormones, including CCK, PYY and GLP-1 [6][7][8]. Because relatively large amounts of protein (up to 55 g, or 226 kcal) are required for these effects, there has been an interest in characterising the effects of amino acids on upper gut functions, energy intake and postprandial blood glucose control, since amino acids are likely to mediate these effects of protein. ...
Article
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In humans, phenylalanine stimulates plasma cholecystokinin (CCK) and pyloric pressures, both of which are important in the regulation of energy intake and gastric emptying. Gastric emptying is a key determinant of postprandial blood glucose. We evaluated the effects of intragastric phenylalanine on appetite perceptions and subsequent energy intake, and the glycaemic response to, and gastric emptying of, a mixed-nutrient drink. The study consisted of two parts, each including 16 healthy, lean males (age: 23 ± 1 years). In each part, participants received on three separate occasions, in randomised, double-blind fashion, 5 g (Phe-5 g) or 10g (‘Phe-10 g) L-phenylalanine, or control, intragastrically, 30 min before a standardised buffet-meal (part A), or a standardised mixed-nutrient drink (part B). In part A, plasma CCK and peptide-YY (PYY), and appetite perceptions, were measured at baseline, after phenylalanine alone, and following the buffet-meal, from which energy intake was assessed. In part B, plasma glucose, glucagon-like peptide-1 (GLP-1), insulin and glucagon were measured at baseline, after phenylalanine alone, and for 2 h following the drink. Gastric emptying of the drink was also measured by 13C-acetate breath-test. Phe-10 g, but not Phe-5 g, stimulated plasma CCK (P = 0.01) and suppressed energy intake (P = 0.012); energy intake was correlated with stimulation of CCK (r = −0.4, P = 0.027), and tended to be associated with stimulation of PYY (r = −0.31, P = 0.082). Both Phe-10 g and Phe-5 g stimulated insulin and glucagon (all P < 0.05), but not GLP-1. Phe-10 g, but not Phe-5 g, reduced overall plasma glucose (P = 0.043) and peak plasma glucose (P = 0.017) in response to the mixed-nutrient drink. Phenylalanine had no effect on gastric emptying of the drink. In conclusion, our observations indicate that the energy intake-suppressant effect of phenylalanine is related to the stimulation of CCK and PYY, while the glucoregulatory effect may be independent of stimulation of plasma GLP-1 or slowing of gastric emptying.
... There are strategies that have been designed to modify postprandial glycaemia to favour lower blood glucose and ROS response balanced system and one of these strategies is the addition of protein to CHO diet or beverages. Studies involving addition of protein to CHO diet or beverages have reported lower glucose response and in contrast, higher insulin response [27][28][29]. Most protein used are mainly dairy protein such as whey protein. ...
Article
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Postprandial hyperglycemia induced by excessive intake of high carbohydrate (CHO) foods and beverages promotes oxidative stress which can cause many health risks such as cardio-metabolic diseases and diabetes. Protein when co-ingested with CHO beverages, has been shown to lower the postprandial glycaemic and insulinemic, which may help to attenuate postprandial reactive oxygen species (ROS) and oxidative stress. Soybean contains isoflavone which may provide potential benefits in regulating postprandial glucose and insulin levels as well as providing protection against ROS production. The aim of this study was to investigate the effects of soybean added CHO beverage on postprandial glycemic, insulinemic and reactive oxygen species responses in healthy men. Eight male [age 20.0 (1.2) years, body weight 59.2 (6.2) kg] consumed 500 ml of CHO added with soybean (SOY + CHO), CHO added with whey protein (WHEY + CHO) and CHO alone (Control) after an overnight fast, in a randomized counterbalanced order crossover design, separated by a one week period. Venous blood samples were collected after overnight fast (baseline) and at 30, 60, 90 and 120 min after consumption of the beverage. The mean area under the insulin curve was lower in SOY + CHO trial compared to CHO + WHEY trial. Similarly, SOY + CHO tended to have a lower postprandial ROS response than CHO + WHEY. However, no significant difference was observed between all beverages in all parameters. Soybean-based beverage may yield lower effect on postprandial ROS suggesting lower oxidative stress due to lower insulinemic responses, compared to whey protein when co-ingested with CHO
... They found that oil-mill wastewater was able to trap reactive carbonyl species such as hydroxycarbonyls and dicarbonyls, which inhibited the formation of Amadori products and N-ε-(carboxymethyl)-lysine (CML), in addition to inhibiting oxidative cleavage and C 2 ÀC 6 cyclization. One limitation to this strategy, however, could be the alteration of the bioactive peptide generation by milk proteins during digestion, some of which are thought to have an antidiabetic effect (Akhavan et al., 2010;Amaya-Farfan et al., 2016; see Chapter 2, Denaturation of Proteins, Generation of Bioactive Peptides, and Alterations of Amino Acids). p0905 Lund and Ray (2017), in turn, have contended that the development of efficient strategies to control the Maillard reactions during food processing requires an understanding of reaction mechanisms and how reaction conditions affect the Maillard products. ...
Chapter
Upon processing or storage foods almost invariably undergo chemical changes that lead to a dramatic discoloration known as nonenzymatic browning or Maillard browning, along with the development of volatile, soluble, and insoluble products bearing far-reaching consequences on the food sensory properties and the long-term health of consumers. This chapter summarizes the chemistry underlying the complex network of different types of reactions, collectively known as the “Maillard reaction.” It is explained how each type of reaction imparts the changes and affects human health emphasizing the molecular events they promote in the body. An updated evaluation is made of both the positive and negative effects highlighting the possible connection between ingested preformed AGEs and the higher susceptibility of elderly individuals to the SARS-type viral infections. The means to control the reactions are reviewed seeking a balance between the technological gains and the health consequences, rather than the nutritional losses.
... The sympathetic nervous system exerts a direct inhibitory influence on α 1 -adrenoceptors and an indirect inhibitory effect on α 2 -adrenoceptors. The parasympathetic nervous system exerts both excitatory and inhibitory control through the vagus nerve by activating intrinsic excitatory (e.g., cholinergic) and inhibitory (e.g., nitric oxide, vasoactive intestinal peptide, somatostatin) nerves in the stomach wall [25,27]. ...
Article
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Sensory and motor functions of the stomach, including gastric emptying and accommodation, have significant effects on energy consumption and appetite. Obesity is characterized by energy imbalance; altered gastric functions, such as rapid gastric emptying and large fasting gastric volume in obesity, may result in increased food intake prior to reaching usual fullness and increased appetite. Thus, many different interventions for obesity, including different diets, anti-obesity medications, bariatric endoscopy, and surgery, alter gastric functions and gastrointestinal motility. In this review, we focus on the role of the gastric and intestinal functions in food intake, pathophysiology of obesity, and obesity management.
... Ingestion of protein, particularly whey, lowers postprandial plasma glucose in healthy individuals and in people with type 2 diabetes (T2D) [1,2]. This beneficial effect of whey protein is associated with slowing of gastric emptying and the stimulation of insulin and the incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) [2][3][4][5][6][7]. ...
Article
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(1) Background: Whey protein lowers postprandial blood glucose in health and type 2 diabetes, by stimulating insulin and incretin hormone secretion and slowing gastric emptying. The branched-chain amino acids, leucine, isoleucine and valine, abundant in whey, may mediate the glucoregulatory effects of whey. We investigated the comparative effects of intragastric administration of leucine, isoleucine and valine on the plasma glucose, C-peptide and glucagon responses to and gastric emptying of a mixed-nutrient drink in healthy men. (2) Methods: 15 healthy men (27 ± 3 y) received, on four separate occasions, in double-blind, randomised fashion, either 10 g of leucine, 10 g of isoleucine, 10 g of valine or control, intragastrically, 30 min before a mixed-nutrient drink. Plasma glucose, C-peptide and glucagon concentrations were measured before, and for 2 h following, the drink. Gastric emptying of the drink was quantified using 13C-acetate breath-testing. (3) Results: Amino acids alone did not affect plasma glucose or C-peptide, while isoleucine and valine, but not leucine, stimulated glucagon (p < 0.05), compared with control. After the drink, isoleucine and leucine reduced peak plasma glucose compared with both control and valine (all p < 0.05). Neither amino acid affected early (t = 0–30 min) postprandial C-peptide or glucagon. While there was no effect on overall gastric emptying, plasma glucose at t = 30 min correlated with early gastric emptying (p < 0.05). (4) Conclusion: In healthy individuals, leucine and isoleucine lower postprandial blood glucose, at least in part by slowing gastric emptying, while valine does not appear to have an effect, possibly due to glucagon stimulation.
... In this study, the absence of physical activity associated with a high-protein diet could have increased glucose levels in the serum of the HD animals. However, authors are still not sure if high-protein diets, specifically supplemented with WP, are beneficial or not, whereas dose and time could play an important role in glycemic response and regulation [32,33]. ...
Article
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There is limited evidence in the scientific literature regarding the chronic use of whey protein and its potentially adverse effects or toxicity. We evaluated the impact of chronic use of whey protein in two doses using an experimental model. Adult male Wistar rats (n = 30) were supplemented with two different doses: 3125 mg/kg and 6250 mg/kg of whey protein isolate for 90 days. Biochemical, hematological, tissue, morphological, and behavioral analysis were evaluated. The whey-treated groups significantly increased their weight compared to the control (p < 0.05). Biochemical and hematological parameters were unchanged, except for glucose, higher in the 6250 mg/kg group (p < 0.05). The behavioral analysis showed no relevant difference (p > 0.05). The organs analysis showed an absolute increase in liver, right kidney, and heart weights in the whey-treated group compared to the control (p < 0.05). This study suggests that whey protein isolate has no toxicity when supplemented at such doses for 90 days. These doses also appeared to have the same effect regarding weight gain and absolute organs weight. This research corroborates with current literature; however, further work is needed to safely investigate the chronic use of whey supplements at a higher dose.
... Among animal proteins, whey and cod proteins have shown remarkable results in improving acute glucose response. Indeed, a sufficient dose (≥ 0.8 g/kg/day) of these proteins associated with reduced carbohydrate intake diminished the glycemic response by increasing insulin secretion and sensitivity in healthy adults (21)(22)(23). However, the long-term effect of high animal protein intake on glucose homeostasis is not yet clearly demonstrated, but it could lead to insulin resistance (17). ...
Article
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Several studies have demonstrated that high protein diets improve glucose homeostasis. Nevertheless, the mechanisms underlying this effect remain elusive. This exploratory study aims to screen and compare the acute effects of dietary proteins from different sources on intestinal glucose absorption. Six dietary proteins from various sources were thus selected and digested thanks to the INFOGEST static gastrointestinal digestion protocol. The digested proteins were able to decrease intestinal glucose absorption in vitro and ex vivo . Moreover, acute ingestion of casein and fish gelatin led to improved glucose tolerance in Wistar rats without significant effect on insulin secretion. In parallel, GLUT2 mRNA expression in enterocytes was decreased following short-term incubation with some of the digested proteins. These results strengthen the evidence that digested protein-derived peptides and amino acids are key regulators of glucose homeostasis and highlight their role in intestinal glucose absorption.
... Studies support the positive effects of whey protein and casein, the major fractions in dairy products on appetite hormones such as GLP-1, PYY and cholecystokinin as well as ghrelin (Akhavan et al., 2010(Akhavan et al., , 2014Bowen et al., 2006). Even so, after a 12-week energy-restricted dietary intervention with high dairy and Ca in overweight/obese adults, a modest increase in plasma PYY concentrations during a mixed meal tolerance test was noticed but no other changes were observed regarding appetite hormone responses that is, GLP-1, GIP, or ghrelin (Jones et al., 2013). ...
Article
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Hunger-reducing effects and beneficial changes in gastrointestinal hormones have been reported, in overweight/obese individuals consuming dairy while yogurt takes pride of place due to its unique structure and composition. Although the contribution of yogurt to metabolic regulation has received growing attention, the research studies which examine its role on appetite are limited, especially regarding type 2 diabetes mellitus (T2DM) patients. The aim of the present study was to investigate the effects of non-fat, conventional yogurt consumption on appetite hormone responses of T2DM patients following a non-energy-restricted diet. Overweight subjects participated in a 12-week dietary intervention including 2 meals/day (2 × 200 g) of yogurt. At the beginning and the end of the intervention, a mixed meal tolerance test assessing the postprandial response of glucose, insulin, ghrelin, glucagon-like peptide-1 (GLP-1), and peptide-YY (PYY) was performed. Subjective appetite ratings were also evaluated. Area under the curve for glucose, insulin, ghrelin, GLP-1, and PYY responses did not differ after the 12-week intervention with yogurt (p > .05) as well as for subjective appetite ratings (p > .05). No significant differences were indicated at specific time points in any of the examined parameters. Regular consumption of non-fat, conventional yogurt for 12-week duration does not affect appetite hormone responses in overweight patients with T2DM following a non-energy-restricted diet.
... Various studies also have reported a protective effect of probiotics or prebiotics in CRC mice models as reviewed [52]. Furthermore, yogurt has been suggested to induce gastrointestinal hormone secretion [53,54]. Our systematic review and meta-analysis had several strengths. ...
Article
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Objective: The consumption of dairy is associated with decreased risk of colorectal cancer (CRC), but few studies have assessed the relationship between dairy consumption and precursors of CRC. Therefore, we performed the first meta-analysis to further evaluate this association. Methods: PubMed, Embase, Scopus, and Web of Science databases were searched through July 2020 for observational studies. Study-specific risk estimates for the highest versus lowest category were pooled using the random-effects and fixed-effects model. The methodological quality of included studies was assessed using the ROBINS-I Scale. Results: A total of 12 studies were included (3 cohort studies and 9 case-control studies). Compared with the lowest level consumption, fermented dairy products had a decreased risk of precursors of CRC in both cohort (RR = 0.92 95% CI: 0.87-0.97) and case-control studies (RR = 0.98 95% CI: 0.96-0.99). Total dairy (RR = 0.80 95% CI: 0.68-0.96) and cheese (RR = 0.96 95% CI: 0.93-0.99) consumption was inversely associated with the risk in case-control studies whereas yogurt consumption was inversely associated with the risk in cohort studies (RR = 0.91 95%CI: 0.86-0.96). No significant associations were found for consumption of total milk and non/low-fat milk. For dose-response analyses, evidence of linear association was found in total dairy and yogurt consumption. The risk decreased by 12% for an increment of 200 g/d total dairy consumption (RR = 0.88 95% CI: 0.81-0.95) and decreased by 8% for an increment of 50 g/d yogurt consumption (RR = 0.92 95% CI: 0.85-0.99). Conclusions: Fermented dairy products, specifically yogurt and cheese, were significantly associated with decreased risk of conventional and serrated precursors of colorectal cancer.
... Indeed, high-fat dairy consumption is known to be inversely related to obesity [59,60], cardiovascular and metabolic diseases [59], and has demonstrated improvement in postprandial glycaemia [61,62]. Hence, it remains to be understood whether the dairy product (French and Mediterranean diets etc.) effects are attributable to the fat content or associated nutrients, especially since dairy products (except butter) are considered rich sources of protein and micronutrients. ...
Article
Obesity and increased body adiposity have been alarmingly increasing over the past decades and have been linked to a rise in food intake. Many dietary restrictive approaches aiming at reducing weight have resulted in contradictory results. Additionally, some policies to reduce sugar or fat intake were not able to decrease the surge of obesity. This suggests that food intake is controlled by a physiological mechanism and that any behavioural change only leads to a short-term success. Several hypotheses have been postulated, and many of them have been rejected due to some limitations and exceptions. The present review aims at presenting a new theory behind the regulation of energy intake, therefore providing an eye-opening field for energy balance and a potential strategy for obesity management.
... Dairy products play an essential role in human life as they provide health benefits beyond basic nutrition. The casein and whey proteins enhance bone health (Rizzoli, 2014), muscle protein retention (Lunn et al., 2012), glycemic regulation (Akhavan, Luhovyy, Brown, Cho, & Anderson, 2010;El Khoury et al., 2014), and weight management (Teegarden & Zemel, 2003). Since milk is a nutritious medium with high water activity, it supports the growth of undesirable microorganisms, and thus makes it unsafe for human consumption. ...
Article
Consumer demand for minimally processed foods continues to increase every day, primarily due to a hike in consumer awareness on food and nutritional security. Chemical preservatives are increasingly becoming ineffective in exterminating microorganisms in food. On the other hand, the potential health risks associated with the chemical preservatives coupled with their regulatory restrictions call for novel and effective antimicrobials originated from safe sources. Therefore, food biopreservation using controlled microbes such as lactic acid bacteria (LAB) or their metabolites has been reviewed as a safer alternative for conventional food processing. Lactic bacterial antagonism against spoilage microbes and pathogens has been correlated with the production of various antimicrobial substances. Among them, phenyllactic acid (PLA) is an important broad-spectrum antimicrobial compound that inhibits the growth of undesirable microbes through multifaceted actions. PLA is a phenolic acid synthesized during phenylalanine and central carbon metabolism of LAB. Although chemical methods of PLA production have been well studied, few limitations such as complex technology routes and high impurities have hampered the PLA synthesis through chemical methods. Alternatively, PLA production using LAB as a whole-cell catalyst remains a feasible and eco-friendly method. In this context, the present review comprehensively recapitulates PLA biosynthetic pathways in the LAB and the methods to enhance the PLA yield through biotechnological and non-biotechnological strategies. Insights into the mechanism of PLA-associated microbial inhibition and anti-virulence actions have been deepened. Various possible food and feed applications of PLA or PLA producing LAB have been summarized. Finally, the regulatory and toxicological status of PLA has been highlighted. Overall, the present review offers factual information on LAB-derived PLA and provides future directions to the researchers to fulfill the existing research gaps.
... Insulin stimulates protein synthesis [18,19], while glucagon increases amino acid catabolism. Some non-PKU studies have shown that nitrogen retention is improved when protein is in the form of oligopeptides compared to whole protein or amino acids [20][21][22]. It is possible that CGMP, a whey derived macropeptide, may promote nitrogen retention improving lean body mass synthesis [23] and improve growth potential in children with PKU. ...
Preprint
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Background: Protein quality and quantity are important factors in determining lean body (muscle) mass (LBM). In phenylketonuria (PKU), protein substitutes provide most of the nitrogen either as amino acids (AA) or glycomacropeptide (CGMP-AA). Body composition and growth are important indicators of long-term health. In a 3-year prospective study comparing the impact of AA and CGMP AA on body composition and growth in PKU, 48 children were recruited. N=19, (median age 11.1y, range 5-15y) took AA only, n=16 (median age 7.3y, range 5-15y) took a combination of CGMP-AA and AA (CGMP50), and 13 children (median age 9.2y, range 5-16y) took CGMP-AA only (CGMP100). A dual energy X ray absorptiometry (DXA) scan at enrolment and 36 months measured LBM, % body fat (%BF) and fat mass (FM). Height was measured at enrolment, 12, 24 and 36 months. Results: No correlation or statistically significant differences were found between the three groups for LBM, FM and height compared with age, gender, puberty or phenylalanine blood concentrations. The change in height z scores: AA 0, CGMP50 +0.4 and CGMP100 +0.7 showed a trend that children in the CGMP100 group were taller, had improved LBM with decreased FM and % BF but this was not statistically significant. Conclusion: There appeared to be no advantage of AA compared to CGMP-AA protein substitutes on body composition after 3 years follow up of usage. Although statistical differences were not reached, a trend towards improved body composition was observed with CGMP when it provided the entire protein substitute requirement. Trial registry: IRAS 129497 (13/WM/10435) registered 10th November 2013 (hppt// www.hra.nhs)
... Insulin stimulates protein synthesis [18,19], while glucagon increases amino acid catabolism. Some non-PKU studies have shown that nitrogen retention is improved when protein is in the form of oligopeptides compared to whole protein or amino acids [20][21][22]. It is possible that CGMP, a whey-derived macropeptide, may promote nitrogen retention, improving lean body mass synthesis [23] and growth potential in children with PKU. ...
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Protein quality and quantity are important factors in determining lean body (muscle) mass (LBM). In phenylketonuria (PKU), protein substitutes provide most of the nitrogen, either as amino acids (AA) or glycomacropeptide with supplementary amino acids (CGMP-AA). Body composition and growth are important indicators of long-term health. In a 3-year prospective study comparing the impact of AA and CGMP-AA on body composition and growth in PKU, 48 children were recruited. N = 19 (median age 11.1 years, range 5–15 years) took AA only, n = 16 (median age 7.3 years, range 5–15 years) took a combination of CGMP-AA and AA, (CGMP50) and 13 children (median age 9.2 years, range 5–16 years) took CGMP-AA only (CGMP100). A dual energy X-ray absorptiometry (DXA) scan at enrolment and 36 months measured LBM, % body fat (%BF) and fat mass (FM). Height was measured at enrolment, 12, 24 and 36 months. No correlation or statistically significant differences (after adjusting for age, gender, puberty and phenylalanine blood concentrations) were found between the three groups for LBM, %BF, FM and height. The change in height z scores, (AA 0, CGMP50 +0.4 and CGMP100 +0.7) showed a trend that children in the CGMP100 group were taller, had improved LBM with decreased FM and % BF but this was not statistically significant. There appeared to be no advantage of CGMP-AA compared to AA on body composition after 3-years of follow-up. Although statistically significant differences were not reached, a trend towards improved body composition was observed with CGMP-AA when it provided the entire protein substitute requirement.
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We evaluated the effects of acute intake of biscuits (B) containing either spent coffee grounds (SCG), (added with fructooligosaccharides; SC‐FOS) or SCG antioxidant dietary fiber (SCF), on satiety, energy intake as well as gastrointestinal tolerance of healthy overweight volunteers. The addition of SCG and SCF to the biscuits (SC‐FOS‐B and SCF‐B) increased their protein (11.4% and 12.2%), and total dietary fiber (8.4% and 11.8%) contents. The SCF‐B significantly increased satiety perception, impacting ad libitum energy intake compared to the traditional biscuits recipe (TB; no added fiber). Moreover, SC‐FOS‐B and SCF‐B decreased (no‐observed‐adverse effect) the most frequently reported symptoms by the participants, demonstrating that doses up to 5 g of SCF (per biscuit portion; 45 g) are well tolerated. The use of SCF and SCG as functional ingredients represents a sustainable strategy for the coffee industry and also potentiates the reduction of overweight, one of the leading health problems among the population. Practical applications The addition of SCF or SCG as food ingredients increases protein and the dietary fiber content of traditional biscuits. SCF can slow gastric emptying, modulate appetite and thus body weight. SCF attenuates carbohydrate digestion blunting post‐prandial blood glucose spikes reducing the risk of type 2 diabetes. SCF can be used as a functional ingredient to formulate foods with health benefits.
Chapter
Based on epidemiological evidence, dairy products appear to play a protective role against type 2 diabetes (T2D). Experimental evidence suggests several mechanisms could be involved in glucose regulation and T2D prevention. In this chapter, we focus on the role of dairy protein as an important modulator of insulin-dependent and independent glucoregulatory pathways. Whey protein, branched-chain amino acids (BCAA), and leucine are potent insulinotropic and insulin action modulators. Additionally, protein stimulates the release of gastrointestinal hormones that regulate appetite, suppress food intake, and maintain energy balance. Finally, bioactive peptides released from dairy proteins during digestion and as fermentation by-products can promote gut hormones and insulin release and action. The dose of proteins, peptides, or amino acids necessary to affect a physiological response exceeds what could be obtained from a normal diet that includes dairy products. However, they remain promising glucose-lowering functional ingredients and alternatives to current pharmacological interventions for T2D.
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Breakfast cereals are often consumed with dairy products or nondairy alternatives; however, the effect of the combination on blood glucose and food intake control is not well investigated. In a randomized, crossover study, 24 healthy women (age: 22.7 ± 2.5 years; body mass index: 22.1 ± 1.5 kg/m ² ) consumed, to satiation, 1 of 3 treatments: Greek yogurt with granola (150 kcal, 9.2 g protein, 2.6 g fat, 2.0 g dietary fibre, and 21.5 g available carbohydrate/100 g); cultured coconut product with granola (146 kcal, 3.2 g protein, 3.2 g fat, 5.6 g dietary fibre, and 21.9 g available carbohydrate/100 g); or water control. The data were analyzed with repeated-measures ANOVA. The 2 h blood glucose iAUC was 52% lower after the dairy compared with nondairy treatment (P < 0.0001). While there were no differences in food intake between the caloric treatments consumed to satiation, protein intake was 3 times higher and fibre intake was 4 times lower after the dairy compared with nondairy treatment. Both caloric treatments resulted in similar suppression of ad libitum food intake at 2 h (P < 0.003) and subjective appetite over 2 h (P < 0.0001) compared with water. The cumulative food intake over 2 h was lower after water (P < 0.05). The 1.8-fold increase in postprandial insulin after dairy compared with nondairy treatment may explain the reduction in blood glucose without an increase in subsequent energy intake. Novelty Blood glucose in young females is lower after a breakfast with granola in a high-protein cultured dairy than when in a high-fibre nondairy cultured product. Subjective appetite over 2 h and food intake 2 h later was similarly lower after both breakfasts but cumulative intake was higher compared with breakfast skipping.
Article
Background This study aims to compare the effects of soy protein isolate (SPI) and soy peptide (PEP) preload 30 min before a 75-g oral glucose tolerance test (OGTT) on the gastric emptying rate, plasma insulin, and blood glucose responses. Methods Nine healthy young subjects were evaluated on four occasions. The participants consumed a 200-ml solution containing either 20 g of SPI or PEP in experiment 1. In experiment 2, 30 min after consuming either 20 g of SPI or PEP solutions, an OGTT was performed to evaluate the individual glycemic response. The gastric emptying rate was measured by the ¹³ C-sodium acetate breath test. Blood glucose and plasma insulin were measured before and after consuming either the SPI or PEP solutions and during the OGTT. Results In experiment 1, plasma insulin levels were higher 30 min after consuming the PEP solution than after the SPI solution. PEP resulted in a faster gastric emptying rate than SPI. In experiment 2, just before performing the OGTT, the plasma insulin response was higher for PEP than for SPI. Fifteen minutes after starting the OGTT, the blood glucose response was lower after consuming PEP than after SPI. The gastric emptying rate tended to be faster after consuming PEP than after SPI ( p = 0.08). Conclusion A PEP preload might be slightly more effective for the suppression of postprandial blood glucose excursion compared with SPI; thus, a PEP preload potentially induces an enhanced insulin response just before the OGTT.
Article
Whey protein (WP) can increase insulin secretion, produce an incretin effect, delay gastric emptying, and regulate appetite, resulting in improved glycemic control. We hypothesized that WP supplementation is associated with postprandial glycemia regulation in persons with type 2 diabetes mellitus (T2DM) and conducted a quantitative meta-analysis of randomized controlled trials (RCTs) to test this hypothesis. We searched PubMed, Embase, Cochrane Library, Scopus databases, and the ClinicalTrials.gov registry for relevant RCTs published before March 2022. We assessed the pooled effects using a random-effects model on glucose and insulin levels at 60 and 120 min, total glucagon-like peptide-1 (tGLP-1) at 30 and 60 min, and the incremental area under the curve (iAUC) of glucose, insulin, tGLP-1, and glucose-dependent insulinotropic polypeptide. Five RCTs involving 134 persons were included. Postprandial glycemia was significantly lower at 60 min (weighted mean difference: −2.67 mmol/L, 95% confidence interval: 3.62 to 1.72 mmol/L) and 120 min (−1.59 mmol/L, −2.91 to −0.28 mmol/L) in WP group than in placebo group. The iAUC of insulin was significantly higher in WP group (24.66 nmol/L × min, 1.65 to 47.66 nmol/L × min) than in placebo group. Although other results favored the WP group, differences between the groups were not statistically significant. The present study showed that premeal WP supplementation is beneficial for postprandial glycemia in persons with mild or well-controlled T2DM without substantial adverse effects. However, the level of certainty of current evidence is not high enough. Further larger and well-designed clinical trials are warranted for evaluating optimal dose and long-term effects of WP supplementation.
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Diet is one of the environmental factors that is recognized to impact our health and the emergence of certain diseases. During gastrointestinal digestion, the major nutrient protein consumed undergoes breakdown and releases several peptides and amino acids. Some of these peptides may act as hormones or neurotransmitters due to their similar characteristics to endogenous peptides. These exogenous food-derived peptides can act on receptors in the body and exert an agonistic or antagonistic activity. One example of such peptides is opioid peptides (Teschemacher 2003). The bioactivity of food-derived peptides depends on their chain length, molecular charge, hydrophobicity and side-chain bulkiness of the constituent amino acid residues (Pripp et al. 2005). Normally, the peptide activity against disease targets is considered as lower than synthetic drugs, but the benefits of dietary bioactive peptides like low health cost, safety, and additional nutritional benefits makes these peptides seem attractive (Udenigwe and Aluko 2012).
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The multiple functions of peptides released from proteins have immense potential in food and health. In the past few decades, research interest in bioactive peptides of plant origin has surged tremendously, and new plant-derived peptides are continually discovered with advances in extraction, purification, and characterization technology. Plant-derived peptides are mainly extracted from dicot plants possessing bioactive functions, including antioxidant, cholesterol-lowering, and antihypertensive activities. Although the distinct functions are said to depend on the composition and structure of amino acids, the practical or industrial application of plant-derived peptides with bioactive features is still a long way off. In summary, the present review mainly focuses on the state-of-the-art extraction, separation, and analytical techniques, functional properties, mechanism of action, and clinical study of plant-derived peptides. Special emphasis has been placed on the necessity of more pre-clinical and clinical trials to authenticate the health claims of plant-derived peptides.
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Peptides derived from milk proteins are associated with a range of different bioactivities, e.g., antioxidant, antihypertensive, antidiabetic, immunomodulatory, antimicrobial, opioid properties. Peptides can be released following in vitro enzymatic hydrolysis, fermentation and in vivo digestion approaches, alone or in combination. The release of bioactive peptides (BAPs) from milk proteins by these processes is reviewed herein. Furthermore, the contribution of in silico approaches in the targeted release and identification of BAPs is outlined. Details of bioactive milk protein derived peptide sequences obtained by enzymatic hydrolysis, fermentation, and in vivo digestion, as well as by using in silico approaches are presented. Examples of the application of membrane processing and chromatographic techniques for milk BAP fractionation and enrichment are described. Research on the production and identification of milk-derived BAPs can contribute to a better understanding of the nutritional benefits of dairy product consumption.
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Dairy products and milk play an important role in a healthy diet as they contribute to the intake of essential nutrients, high-quality proteins, and fats. Despite the large number of existing studies on the possible association between dairy products and chronic degenerative diseases, studies examining the effects of dairy products and milk on the risk of common causes of mortality such as cardiovascular and neoplastic diseases are scarce and conflicting. Some studies have reported an increased risk of cardiovascular diseases for individuals who consume large amounts of cheese, whereas others have shown no relationship between these products and atherosclerotic biomarkers.
Thesis
Le niveau d’apport protéique est contrôlé de façon très précise par des signaux agissant sur le comportement alimentaire qui visent à atteindre et réguler un niveau d’apport « cible », communément de 10-20% de l’apport énergétique, pour équilibrer le bilan azoté. Cependant, les études d’auto-sélection alimentaire montrent que les rats, mais aussi d’autres espèces, ayant la possibilité de séparer le contrôle de l’ingestion des protéines du contrôle de l’ingestion des glucides et des lipides consomment en moyenne 30% de protéines. L’homéostasie protéique ne semble donc pas être le seul critère qui régule le niveau d’apport protéique. Certaines études suggèrent en effet que l’ingestion d’un niveau élevé de protéines au dépend des glucides aurait des effets métaboliques positifs permettant de réduire la dépendance du métabolisme vis-à-vis de l’insuline, de limiter la prise de poids et de gras, et de réduire le développement de syndromes métaboliques. L’objectif de cette thèse était de mieux comprendre les mécanismes de contrôle de l’ingestion de protéine et leur interaction avec le contrôle énergétique. Les travaux réalisés ont montré que même si une teneur en protéine de 15% était suffisante pour assurer le métabolisme protéique, elle ne l’était pas pour optimiser le métabolisme énergique par rapport au niveau sélectionné par les rats. Le niveau protéique choisi était en moyenne de 30%, et était défendu en s’ajustant à la quantité et à la qualité des glucides proposés, notamment en diminuant proportionnellement à la baisse de l’index glycémique des régimes. Nos résultats suggèrent aussi que FGF21 joue un rôle dans l'orientation des choix alimentaires vers les protéines, puisque les rats en auto-sélection alimentaire maintiennent des taux plasmatiques de FGF21 très bas. Enfin, les taux de FGF21 n’étaient régulés que part le niveau d’apport protéique, et étaient insensibles à l’apport glucidique.
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Dairy snacks are available in various physical forms and their consumption is linked to improved metabolic health. The objective of this study was to determine the effect of dairy snacks of different physical forms on short-term food intake (FI), subjective appetite, and the stress hormone, cortisol, in children. Following a repeated-measures crossover design, 40 children aged 9–14 years randomly consumed 1 of 5 isoenergetic (180 kcal) snacks per study session. These snacks included solid (potato chips, cookies, and cheese), semi-solid (Greek yogurt), and fluid (2% fat milk) snacks. FI was measured 120 min after snack consumption. Subjective appetite was measured at 0 (immediately before the snack), 15, 30, 45, 60, 90, and 120 min. Salivary cortisol (n = 18) was measured after the Greek yogurt and cookie snacks at 0, 30, 60, 90, and 120 min. FI did not differ between snacks (P = 0.15). The Greek yogurt (P < 0.0001) and cheese (P = 0.0009) snacks reduced average appetite compared with the 2% fat milk snack. Salivary cortisol levels were not affected by snack (P = 0.84). This study demonstrates that dairy snacks are as effective as other popular snacks at influencing subsequent FI. However, solid and semi-solid dairy snacks are more effective at repressing subjective appetite than a fluid dairy snack. Registered at ClinicalTrials.gov (NCT02484625). Novelty: Milk, Greek yogurt and cheese have a similar effect on short-term food intake in children as popular potato chips and cookie snacks. Solid, semi-solid and liquid snacks have a similar effect on short-term food intake in children.
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The increasing prevalence of non-communicable diseases has shifted the consumers' preference for food products with sustained glucose release. The investigation wasundertaken to modulate the pattern of carbohydrate digestibility of wheat flour (which is a staple) using oilseed and milk proteins at different levels, which form the binary matrix and with varying levels of fat which form the tertiary matrix. The effect of starch-water gelatinization systems in different ratios (1:10, 1:20) wasalso studied. Whey protein concentrates and casein reduced the rapidly available glucose (RAG) to a significant extent at 5% protein (p<0.0001). The addition of fat decreased the RAG further by 1-4%, and RAG increased as a function of hydration (p< 0.0001). The enthalpy values from differential scanning calorimeter revealed that soy protein concentrate and whey protein werethe least, at 3.15 J/g and 3.24 J/g, respectively, which further decreased with fat at 1.52 J/g and 2.81 J/g. Carbohydrate digestibility wasmodulated by the interaction of macronutrients in the matrix that wasfurther aided by hydrothermal treatment. The extrapolation of the concept resulted in the formulation of Neer dosa - an instant protein-enriched Indian pancake with sustained carbohydrate digestibility. This article is protected by copyright. All rights reserved
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Background: Under dietary self-selection (DSS), rats ingest 25-30% of energy as protein. This high level appears to be explained by metabolic benefits related to reduced carbohydrate dependence and associated pathologies. However, the mechanisms underlying these choices remain largely misunderstood. Objectives: The aim was to test the hypothesis that in a DSS model, rats select a protein-to-energy (PE) ratio to maintain the protein-to-carbohydrate (PC) ratio constant and that fibroblast growth factor 21 (FGF21) is involved in this response. Methods: Adult male Wistar rats were used in 3 experiments. The first was to determine whether the PE ratio was influenced by changes in carbohydrate content. The second was to test whether the PE ratio was defended with a modified DSS model. The third was to determine whether the selected PE ratio was of metabolic interest compared with a standard 15% protein diet. Food intake, body weight, and energy expenditure were measured. After 3 wk, plasma was sampled and rats were killed to determine body composition and gene expression. Statistical analyses were mainly done by ANOVA tests and correlation tests. Results: The selected PE ratio increased from 20% to 35% when the carbohydrate content of the protein-free diet increased from 30% to 75% (R2 = 0.56; P < 10-6). Consequently, the PC ratio was constant (70%) in all groups (P = 0.18). In self-selecting rats, plasma FGF21 concentrations were 3 times lower than in rats fed the 5% protein diet (P < 10-4) and similar to those in rats fed a 30% diet. Conclusions: This study showed that self-selecting rats established PE ratios larger than those considered sufficient to achieve optimal growth in adult rats (10-15%), and the ratios were highly dependent on carbohydrates, apparently with the aim of maintaining a constant and high PC ratio. This was associated with a minimization of plasma FGF21.
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Due to their nutritive value and functionality, whey proteins have been used in many food applications. The efficacy of adding different levels (0, 5, 10 and 20 g kg–1 diet) of whey protein concentrate powder (WPCP) was addressed on the growth performance, feed utilization, and the immune responses of Oreochromis niloticus fingerlings in the current study for 8 weeks. A significant increase was observed in the growth performance (final weight, total weight gain, average daily gain, relative growth rate, and specific growth rate), the feed utilization (feed conversion ratio, protein efficiency ratio, protein productive value, and energy utilization), and the whole-body composition (dry matter, and crude protein) parameters. These levels also significantly improved both the hematological parameters (hemoglobin, red blood cells, packed cell volume, and platelets), and the immune responses indicators (white blood cells, lymphocytes, and serum immunoglobulin M) of the O. niloticus fingerlings. Partially, in all tested parameters, the addition of the high-level 20g WPCP kg–1 diet showed a remarkable superiority among other levels. Remarkably, the beneficial use of WPCP at the level of 20 g kg–1 diet was proved as a promising growth promoter and immune stimulant agent for O. niloticus fingerlings, and may in return, increase fish productivity, health, and profitability in fish farms.
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Research investigating hemp protein consumption on glycemic response is limited. The effects of hemp protein consumption on blood glucose (BG), insulin, and satiety compared with soybean protein and a carbohydrate control were examined. Two acute randomized repeated-measures crossover experiments were conducted. In both, participants consumed the following isocaloric treatments: 40 g of hemp protein (hemp40), 20 g of hemp protein (hemp20), 40 g of soybean protein (soy40), 20 g of soybean protein (soy20), and a carbohydrate control. In experiments 1 (n = 27) and 2 (n = 16), appetite and BG were measured before (0–60 min, pre-pizza) and after a pizza meal (80–200 min, post-pizza). In experiment 1, food intake was measured at 60 min by ad libitum meal; in experiment 2 a fixed meal was provided (based on body weight) and insulin was measured pre-pizza and post-pizza. In both experiments, BG response was affected by treatment (p < 0.01), time (p < 0.001) and time-by-treatment (p < 0.001) from 0–200 min. Protein treatments lowered 0–60-min BG overall mean and area under the curve compared with control (p < 0.05) dose-dependently. In experiment 2, hemp40 and soy40 lowered (p < 0.05) overall mean insulin concentrations compared with hemp20, soy20, and control pre-meal. Results suggest that hemp protein, like soybean, dose-dependently lowers postprandial BG and insulin concentrations compared with a carbohydrate control. Clinical trial registry: NCT02366598 (experiment 1) and NCT02458027 (experiment 2). Novelty: Hemp protein concentrate dose-dependently leads to lower postprandial BG response compared with a carbohydrate control. No differences were seen between hemp and soy protein.
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Continuing studies show that whey components, notably proteins, have valuable nutritional and techno-functional properties supporting their applications in foods and drinks. Complementing these features is the increasing evidence of the health-promoting characteristics of whey proteins and peptides. This paper reviews whey production, composition, and the physico-chemical characteristics of whey proteins and peptides, and critically reviews the health-promoting traits of these components. The role that whey proteins and peptides may play in the prevention and/or adjunctive treatment of various lifestyle and ageing diseases (e.g., diabetes, cancer, liver disease, sarcopenia, cardiovascular disease) are covered. Where possible, the mechanisms of action for the various bioactivities are reviewed, as is the usefulness of whey proteins and peptides in protecting, stabilising and delivering functional food components, notably nano-based systems. This paper highlights the bright future for whey proteins and peptides based on their valuable nutritional, techno-functional and bioactive characteristics, but particularly their health-promoting functions.
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The speed of absorption of dietary amino acids by the gut varies according to the type of ingested dietary protein. This could affect postprandial protein synthesis, breakdown, and deposition. To test this hypothesis, two intrinsically 13C-leucine-labeled milk proteins, casein (CAS) and whey protein (WP), of different physicochemical properties were ingested as one single meal by healthy adults. Postprandial whole body leucine kinetics were assessed by using a dual tracer methodology. WP induced a dramatic but short increase of plasma amino acids. CAS induced a prolonged plateau of moderate hyperaminoacidemia, probably because of a slow gastric emptying. Whole body protein breakdown was inhibited by 34% after CAS ingestion but not after WP ingestion. Postprandial protein synthesis was stimulated by 68% with the WP meal and to a lesser extent (+31%) with the CAS meal. Postprandial whole body leucine oxidation over 7 h was lower with CAS (272 ± 91 μmol⋅kg−1) than with WP (373 ± 56 μmol⋅kg−1). Leucine intake was identical in both meals (380 μmol⋅kg−1). Therefore, net leucine balance over the 7 h after the meal was more positive with CAS than with WP (P < 0.05, WP vs. CAS). In conclusion, the speed of protein digestion and amino acid absorption from the gut has a major effect on whole body protein anabolism after one single meal. By analogy with carbohydrate metabolism, slow and fast proteins modulate the postprandial metabolic response, a concept to be applied to wasting situations.
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We evaluated whether a whey preload could slow gastric emptying, stimulate incretin hormones, and attenuate postprandial glycemia in type 2 diabetes. Eight type 2 diabetic patients ingested 350 ml beef soup 30 min before a potato meal; 55 g whey was added to either the soup (whey preload) or potato (whey in meal) or no whey was given. Gastric emptying was slowest after the whey preload (P < 0.0005). The incremental area under the blood glucose curve was less after the whey preload and whey in meal than after no whey (P < 0.005). Plasma glucose-dependent insulinotropic polypeptide, insulin, and cholecystokinin concentrations were higher on both whey days than after no whey, whereas glucagon-like peptide 1 was greatest after the whey preload (P < 0.05). Whey protein consumed before a carbohydrate meal can stimulate insulin and incretin hormone secretion and slow gastric emptying, leading to marked reduction in postprandial glycemia in type 2 diabetes.
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Type II diabetic subjects were given 50 g protein, 50 g glucose, or 50 g glucose with 50 g protein as a single meal in random sequence. The plasma glucose and insulin response was determined over the subsequent 5 h. The plasma glucose area above the baseline following a glucose meal was reduced 34% when protein was given with the glucose. When protein was given alone, the glucose concentration remained stable for 2 h and then declined. The insulin area following glucose was only modestly greater than with a protein meal (97 +/- 35, 83 +/- 19 microU X h/ml, respectively). When glucose was given with protein, the mean insulin area was considerably greater than when glucose or protein was given alone (247 +/- 33 microU X h/ml). When various amounts of protein were given with 50 g glucose, the insulin area response was essentially first order. Subsequently, subjects were given 50 g glucose or 50 g glucose with 50 g protein as two meals 4 h apart in random sequence. The insulin areas were not significantly different for each meal but were higher when protein + glucose was given. After the second glucose meal the plasma glucose area was 33% less than after the first meal. Following the second glucose + protein meal the plasma glucose area was markedly reduced, being only 7% as large as after the first meal. These data indicate that protein given with glucose will increase insulin secretion and reduce the plasma glucose rise in at least some type II diabetic persons.
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Several clinical conditions suggest an effect of sex steroids on glucose homeostasis in women. Studies examining this phenomenon have yielded controversial results. To investigate the effect of the menstrual cycle on insulin sensitivity, glucose effectiveness and acute insulin response to glucose using the tolbutamide-modified intravenous glucose tolerance test (IVGTT) during the follicular (day 8 +/- 1) and luteal (day 23 +/- 1) phases of the menstrual cycle, the authors recruited 12 healthy regularly menstruating women. All had fasting glucose concentration of < 100 mg/dl [corrected] (89.7 +/- 6.2) with no family history of diabetes mellitus; their body mass indices were < 25 kg/m2 (22.41 +/- 1.44 kg/m2). The mean insulin sensitivity (Si) values decreased during the cycle. Insulin sensitivity (Si x 10(-4)/min.mU/ml) was higher in the follicular phase (5.03 +/- 0.72) and decreased in the luteal phase (2.22 +/- 0.45) (p < 0.001). Glucose effectiveness (Sg min-1) did not change as a function of the phase of the menstrual cycle. Sg estimates were 0.0229 +/- 0.00323 in the follicular phase, and 0.0225 +/- 0.00319 (p = NS) in the luteal phase, respectively. Acute insulin response (AIRg mU/ml) was 276.4 +/- 27.8 in the follicular phase. An adaptive increase (304.4 +/- 51.1) in response to the insulin resistance during the luteal phase was observed, but this increase was not statistically significant (p = NS). Knowledge of the variations in insulin sensitivity that occur during the normal menstrual cycle provides a basis of comparison for studies of other clinical conditions. Also, this phenomenon should be considered if the determination of insulin resistance is the purpose of certain epidemiological studies.
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Acute changes in the blood glucose concentration have a major reversible effect on esophageal, gastric, intestinal, gallbladder, and anorectal motility in both healthy subjects and diabetic patients. For example, gastric emptying is slower during hyperglycemia than euglycemia and accelerated during hypoglycemia. Acute hyperglycemia also affects perceptions arising from the gastrointestinal tract and may accordingly, be important in the etiology of gastrointestinal symptoms in diabetes. Elevations in blood glucose that are within the normal postprandial range also affect gastrointestinal motor and sensory function. Upper gastrointestinal motor function is a critical determinant of postprandial blood glucose concentrations by influencing the absorption of ingested nutrients. Interventions that reduce postprandial hyperglycemia, by modulating the rate of gastric emptying, have the potential to become mainstream therapies in the treatment of diabetes.
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The purpose of this study was to determine whether the fasting glucose/insulin ratio is a useful screening test for insulin resistance in prepubertal girls with premature adrenarche. The glucose/insulin ratio was compared with the insulin sensitivity index calculated from the frequently sampled iv glucose tolerance test with tolbutamide using the minimal model computer program. Thirty-three prepubertal girls (22 Caribbean Hispanic and 11 African American; mean age, 6.8 yr; bone age, 8 yr) were studied. All underwent a 60-min ACTH stimulation test. The fasting glucose/insulin ratio was also compared with IGF-binding protein-1 and ACTH-stimulated androgen levels. Insulin sensitivity correlated significantly with the glucose/insulin ratio (0.76; P < 0.001), fasting insulin (0.75; P < 0.001), and IGF-binding protein-1 (0.59; P < 0.005). Stepwise regression analysis with the insulin sensitivity index as the dependent variable showed that the fasting glucose/insulin ratio was significantly predictive of the insulin sensitivity index (P < 0.002). When viewed as a screening test, setting a value of the fasting glucose/insulin ratio of less than 7 as abnormal and of less than 5.7 x 10(-4) min/microU.ml for the insulin sensitivity index as evidence of insulin resistance (normal prepubertal insulin sensitivity index, >5.7 x 10(-4) min/microU.ml), the sensitivity of the fasting glucose/insulin ratio was 87%, and the specificity was 89%. Furthermore, those girls with a low glucose/insulin ratio (<7) had higher body mass index, fasting insulin, free T, and ACTH-stimulated 17-hydroxypregnenolone and lower fasting IGF-binding protein-1 and SHBG than those girls with a glucose/insulin ratio greater than 7. The fasting glucose/insulin ratio is a useful screening test for insulin resistance in prepubertal Caribbean Hispanic and African American girls with premature adrenarche.
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Protein, generally agreed to be the most satiating macronutrient, may differ in its effects on appetite depending on the protein source and variation in digestion and absorption. We investigated the effects of two milk protein types, casein and whey, on food intake and subjective ratings of hunger and fullness, and on postprandial metabolite and gastrointestinal hormone responses. Two studies were undertaken. The first study showed that energy intake from a buffet meal ad libitum was significantly less 90 min after a 1700 kJ liquid preload containing 48 g whey, compared with an equivalent casein preload (P<0.05). In the second study, the same whey preload led to a 28 % increase in postprandial plasma amino acid concentrations over 3 h compared with casein (incremental area under the curve (iAUC), P<0.05). Plasma cholecystokinin (CCK) was increased by 60 % (iAUC, P<0.005), glucagon-like peptide (GLP)-1 by 65 % (iAUC, P<0.05) and glucose-dependent insulinotropic polypeptide by 36 % (iAUC, P<0.01) following the whey preload compared with the casein. Gastric emptying was influenced by protein type as evidenced by differing plasma paracetamol profiles with the two preloads. Greater subjective satiety followed the whey test meal (P<0.05). These results implicate post-absorptive increases in plasma amino acids together with both CCK and GLP-1 as potential mediators of the increased satiety response to whey and emphasise the importance of considering the impact of protein type on the appetite response to a mixed meal.
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The influence of protein fractionation on gastric emptying and rate of appearance of their constituent amino acids in peripheral blood remains unknown. To examine the influence of the degree of protein fractionation on gastric emptying, gastric secretion, amino acid absorption and enterogastrone response, after the intragastric administration of complete cow milk proteins or their respective peptide hydrolysates in man. Six healthy males were randomized to receive one of the following four solutions: whey whole protein (W), casein whole protein (C), whey peptide hydrolysate (WHY) or casein hydrolysate (CAHY). All solutions were matched for volume (600 mL), nitrogen content (9.3 g/L), energy density (1069-1092 kJ/L), osmolality (288-306 mosmol/kg), pH (6.9-7.0) and temperature (37 degrees C). Solutions were emptied at similar rates, with mean half-times of (mean +/- SEM) 21.4 +/- 1.3, 19.3 +/- 2.2, 18.0 +/- 2.5 and 19.4 +/- 2.8 min, for the WHY, CAHY, C and W, respectively. The rates of intestinal absorption of water and amino acids were similar with the exception of the casein protein solution, for which the speed of intestinal amino acid absorption was slower (p < 0.05). The peptide hydrolysates elicited about 50% more gastric secretion than the whole protein solutions ( p < 0.05),which was accompanied by higher glucose-dependent insulinotropic polipeptide (GIP) plasma levels during the first 20 min of the gastric emptying process. Similar glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) plasma responses were elicited by the four solutions. The rate of gastric emptying and the plasma GLP-1 and PYY responses to feeding with cow milk protein solutions in humans are independent of the degree of protein fractionation and are not altered by small differences in the amino acid composition or protein solubility. In contrast, the GIP response is accentuated when milk proteins are delivered as peptide hydrolysates.
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Background:Whey proteins have insulinotropic effects and reduce the postprandial glycemia in healthy subjects. The mechanism is not known, but insulinogenic amino acids and the incretin hormones seem to be involved. Objective:The aim was to evaluate whether supplementation of meals with a high glycemic index (GI) with whey proteins may increase insulin secretion and improve blood glucose control in type 2 diabetic subjects. Design:Fourteen diet-treated subjects with type 2 diabetes were served a high-GI breakfast (white bread) and subsequent high-GI lunch (mashed potatoes with meatballs). The breakfast and lunch meals were supplemented with whey on one day; whey was exchanged for lean ham and lactose on another day. Venous blood samples were drawn before and during 4 h after breakfast and 3 h after lunch for the measurement of blood glucose, serum insulin, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide 1 (GLP-1). Results:The insulin responses were higher after both breakfast (31%) and lunch (57%) when whey was included in the meal than when whey was not included. After lunch, the blood glucose response was significantly reduced [−21%; 120 min area under the curve (AUC)] after whey ingestion. Postprandial GIP responses were higher after whey ingestion, whereas no differences were found in GLP-1 between the reference and test meals. Conclusions:It can be concluded that the addition of whey to meals with rapidly digested and absorbed carbohydrates stimulates insulin release and reduces postprandial blood glucose excursion after a lunch meal consisting of mashed potatoes and meatballs in type 2 diabetic subjects.
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This chapter discusses the role of milk and dairy products, and their ingredients in obesity and the regulation of food intake and components of metabolic syndrome. In addition to protein (whey and casein), fat (saturated, mono- and poly-unsaturated fatty acids) and carbohydrate (lactose), milk contains biologically active substances such as immunoglobulins, enzymes, antimicrobial peptides, oligosaccharides, hormones, cytokines and growth factors. Each of these may affect food intake and metabolic regulation through a large number of physiologic mechanisms. Thus, their actions may explain the positive health associations between more frequent dairy consumption, a healthier body weight, and decreased risk of developing the metabolic syndrome.
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We previously have shown that ingested beef protein is just as potent as glucose in stimulating a rise in insulin concentration in type II diabetic patients. A synergistic effect was seen when given with glucose. Therefore, we considered it important to determine if other common dietary proteins also strongly stimulate an increase in insulin concentration when given with glucose. Seventeen type II (non-insulin-dependent) untreated diabetic subjects were given single breakfast meals consisting of 50 g glucose, or 50 g glucose plus 25 g protein in the form of lean beef, turkey, gelatin, egg white, cottage cheese, fish, or soy. The peripheral plasma concentrations of glucose, insulin, glucagon, alpha amino nitrogen, urea nitrogen, free fatty acids, and triglycerides were measured. Following ingestion of the meals containing protein, the plasma insulin concentration was increased further and remained elevated longer compared with the meal containing glucose alone. The relative area under the insulin response curve was greatest following ingestion of the meal containing cottage cheese (360%) and was least with egg white (190%) compared with that following glucose alone (100%). The glucose response was diminished following ingestion of the meals containing protein with the exception of the egg white meals. The peripheral glucagon concentration was decreased following ingestion of glucose alone and increased following all the meals containing protein. The alpha amino nitrogen concentration varied considerably. It was decreased after glucose alone, was unchanged after egg white ingestion, and was greatest after ingestion of gelatin. The free fatty acid concentration decrease was 4- to 8-fold greater after the ingestion of protein with glucose compared with ingestion of glucose alone.
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The objective of these 4 studies was to describe the effects of protein source, time of consumption, quantity, and composition of protein preloads on food intake in young men. Young men were fed isolates of whey, soy protein, or egg albumen in sweet and flavored beverages (400 mL) and provided a pizza meal 1-2 h later. Compared with the water control, preloads (45-50 g) of whey and soy protein, but not egg albumen, suppressed food intake at a pizza meal consumed 1 h later. Meal energy intake after egg albumen and soy, but not after control or whey treatments, was greater when the treatments were given in the late morning (1100 h) compared with earlier (0830-0910 h). Suppression of food intake after whey protein, consumed as either the intact protein or as peptides, extended to 2 h. Altering the composition of the soy preload (50 g) by reducing the soy protein content to 25 g and by adding 25 g of either glucose or amylose led to a loss in suppression of food intake by the preload. Egg albumen, in contrast to whey and soy preloads, increased cumulative energy intake (sum of the energy content of the preload plus that in the test meal) relative to the control. We conclude that protein source, time of consumption, quantity, and composition are all factors determining the effect of protein preloads on short-term food intake in young men.
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In cohort studies, insoluble fiber has been associated with a reduced risk of obesity and diabetes; however, compared with soluble fiber, its role in the regulation of short-term food intake (FI) and satiety has received little attention. Our aim was to compare the effects of a high-insoluble-fiber (HF) cereal with a low-fiber (LF) cereal on FI, subjective appetite (SA), and plasma glucose (PG) in healthy individuals. Males and females (n = 32) were randomly assigned to consume 60 g of either HF (26 g insoluble fiber, 120 kcal) or LF (1 g fiber, 217 kcal) breakfast cereal. Pre- and postlunch SA and PG were measured regularly for 4 h, and ad libitum FI was measured at 3 h. The prelunch SA area under the curve did not differ between the 2 cereals, but when expressed as change in appetite per kilocalorie of cereal, HF suppressed SA more than did LF (-17.6 +/- 1.8 compared with -10.0 +/- 1.1 mm . min . kcal(-)(1), respectively; P < 0.01). Lunchtime FI did not differ between cereals, but cumulative energy intake (cereal + lunch) was lower after the HF than after the LF cereal (1330 +/- 57 compared with 1422 +/- 66 kcal, respectively; P = 0.01). The prelunch PG area under the curve (P < 0.0001) and the immediate postlunch PG (P = 0.01) were lower after HF cereal consumption. An HF breakfast cereal contributes to a cumulative reduction in breakfast and lunch energy intake, possibly due to its high satiety value per kilocalorie. A short-term benefit of the HF cereal, compared with LF cereal, was lower PG concentration before and immediately after lunch.
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There is controversy regarding the clinical utility of classifying foods according to their glycemic responses by using the glycemic index (GI). Part of the controversy is due to methodologic variables that can markedly affect the interpretation of glycemic responses and the GI values obtained. Recent studies support the clinical utility of the GI. Within limits determined by the expected GI difference and by the day-to-day variation of glycemic responses, the GI predicts the ranking of the glycemic potential of different meals in individual subjects. In long-term trials, low-GI diets result in modest improvements in overall blood glucose control in patients with insulin-dependent and non-insulin-dependent diabetes. Of perhaps greater therapeutic importance is the ability of low-GI diets to reduce insulin secretion and lower blood lipid concentrations in patients with hypertriglyceridemia.
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The relationships between gastric emptying and intragastric distribution of glucose and oral glucose tolerance were evaluated in 16 healthy volunteers. While sitting in front of a gamma camera the subjects drank 350 ml water containing 75 g glucose and 20 MBq 99mTc-sulphur colloid. Venous blood samples for measurement of plasma glucose, insulin and gastric inhibitory polypeptide were obtained at--2, 2,5,10,15,30,45,60,75,90,105,120 and 150 min. Gastric emptying approximated a linear pattern after a short lag phase (3.3 +/- 0.8 min). The 50% emptying time was inversely related to the proximal stomach 50% emptying time (r = -0.55, p < 0.05) and directly related to the retention in the distal stomach at 120 min (r = 0.72, p < 0.01). Peak plasma glucose was related to the amount emptied at 5 min (r = 0.58, p < 0.05) and the area under the blood glucose curve between 0 and 30 min was related to the amount emptied at 30 min (r = 0.58, p < 0.05). In contrast, plasma glucose at 120 min was inversely related to gastric emptying (r = -0.56, p < 0.05) and plasma insulin at 30 min (r = -0.53, p < 0.05). Plasma insulin at 120 min was inversely related (r = -0.65, p < 0.01) to gastric emptying. The increase in plasma gastric inhibitory polypeptide at 5 min was related directly to gastric emptying (r = 0.53, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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To assess the impact of increased consumption of milk, without other dietary advice, on older adults' energy and nutrient intakes, weight, cardiovascular risk factors (blood pressure, plasma lipid levels), and quality of life. Two hundred four healthy men and women, aged 55 to 85 years, who consumed fewer than 1.5 dairy servings per day were chosen from six US academic health centers. Randomized, controlled open trial. Advice to increase skim or 1% milk intake by 3 cups per day (n = 101) or to maintain usual diet (n = 103) for 12 weeks after a 4-week baseline period. Changes in energy and nutrient intake assessed from 3-day food records, body weight, blood pressure, and plasma lipid levels. Group-by-time analysis of variance with repeated-measures, chi 2 test. Compliance with the intervention was good. Compared with controls, participants in the milk-supplemented group significantly increased energy, protein, cholesterol, vitamins A, D, and B-12, riboflavin, pantothenate, calcium, phosphorus, magnesium, zinc, and potassium intakes. Prevalence of nutrient inadequacy, assessed for nutrients with Estimated Average Requirements, decreased among women in the milk group for magnesium (40% at baseline vs 13% at 12 weeks, P < .001) and vitamin B-12 (6% vs 0%, P < .05) and tended to decrease (P < .10) for protein and thiamin (women) and magnesium and vitamin B-6 (men). The milk group gained 0.6 kg more than control group (P < .01); however, weight gain was less than predicted, which suggests some compensation for the added energy from milk. Blood pressure decreased similarly over time in both groups. Total and low-density lipoprotein cholesterol levels, and the ratio of total cholesterol to high-density lipoprotein cholesterol, were unchanged. Triglyceride levels increased within the normal range in the milk group (P = .002). Quality of life scores were high at baseline and remained high throughout. Older adults can successfully increase milk intake, thereby meaningfully improving their nutrient intakes. Dietitians can play a key role in disseminating this advice.
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We hypothesized that the digestion of proteins gives rise to peptides that initiate several satiety signals from the gut, and that the signals arising will be dependent on the protein source. The role of peripheral opioid and cholecystokinin (CCK)-A receptors was investigated. Casein, soy protein, and casein and soy hydrolysates were administered to rats by gavage (0.5 g protein/4 mL water). Food intake was measured over 2 h. The opioid receptor antagonist, naloxone methiodide (1.0 mg/kg) given intraperitoneally (i.p.), increased food intake when given at the same time as the hydrolysate preloads, 25 min after the casein preloads and 55 min after the soy protein preloads. The CCK-A receptor antagonist, devazepide (which reverses protein-induced food intake suppression), when given at 0.25 mg/kg, i.p., 60 min before preloads of each of three soy hydrolysates, also blocked suppression of food intake, but the strength and duration of the interaction depended on the preparation. When the two receptor antagonists were both administered with soy or casein preloads, their effects were additive. We conclude that peptides arising from digestion contribute to satiety by independent activation of both opioid and CCK-A receptors.
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Subjects with anorexia nervosa (AN) at low weight display metabolic, endocrine, and behavioral abnormalities. Whether these various differences are a consequence of the condition and persist after recovery is unclear. We tested the hypothesis that abnormalities in the insulin and leptin axes and in the desire to eat persisted in subjects who had recovered from AN in terms of body mass index (BMI) and menstrual function. Endocrine, metabolic, and psychological parameters were assessed by sampling under fasting conditions and serially in response to a standard meal. Subjects included 18 females recovered from AN and 18 female controls and measures included plasma insulin, leptin, glucose and beta-hydroxybutyrate (beta-HBA) concentrations together with desire to eat. Fasting glucose concentrations were normal in both groups, but fasting insulin concentrations were significantly lower and the fasting glucose/insulin ratio significantly higher in the recovered subjects. The glucose concentration was significantly higher at the end of the meal period in the recovered group. The peak increase of insulin during the meal was significantly less in the recovered group and in response to the meal, glucose/insulin ratios were significantly higher for the first 45 minutes indicating a delayed insulin response. Fasting beta-HBA concentrations were not significantly different between groups, but postmeal decreases were significant and larger in the recovered AN group. Fasting and meal-related leptin concentrations were not significantly different between the groups and in both groups were correlated with BMI. In controls, but not in recovered subjects, the reported desire to eat was correlated with plasma glucose and leptin concentrations. The insulin, glucose and beta-HBA data indicated the presence of insulin hypersensitivity in the recovered subjects. As the insulin response to the meal was blunted and apparently delayed, there may be a persistent alteration in pancreatic function as a long-term pathological consequence of the anorexia. Alternatively, these data indicate a possible trait marker for AN.
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This review presents 4 lines of evidence supporting a role for proteins in the regulation of food intake and maintenance of healthy body weights. It is concluded that the protein content of food, and perhaps its source, is a strong determinant of short-term satiety and of how much food is eaten. Although the role of protein in the regulation of long-term food intake and body weight is less clear, the evidence reviewed suggests that further research to define its role is merited. Such research has the potential to lead to new functional foods, food formulations, and dietary recommendations for achieving healthy body weights.
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Milk products deviate from other carbohydrate-containing foods in that they produce high insulin responses, despite their low GI. The insulinotropic mechanism of milk has not been elucidated. The objective was to evaluate the effect of common dietary sources of animal or vegetable proteins on concentrations of postprandial blood glucose, insulin, amino acids, and incretin hormones [glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1] in healthy subjects. Twelve healthy volunteers were served test meals consisting of reconstituted milk, cheese, whey, cod, and wheat gluten with equivalent amounts of lactose. An equicarbohydrate load of white-wheat bread was used as a reference meal. A correlation was found between postprandial insulin responses and early increments in plasma amino acids; the strongest correlations were seen for leucine, valine, lysine, and isoleucine. A correlation was also obtained between responses of insulin and GIP concentrations. Reconstituted milk powder and whey had substantially lower postprandial glucose areas under the curve (AUCs) than did the bread reference (-62% and -57%, respectively). Whey meal was accompanied by higher AUCs for insulin (90%) and GIP (54%). It can be concluded that food proteins differ in their capacity to stimulate insulin release, possibly by differently affecting the early release of incretin hormones and insulinotropic amino acids. Milk proteins have insulinotropic properties; the whey fraction contains the predominating insulin secretagogue.
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Despite the proven efficacy of the established high-carbohydrate diets for treatment and prevention of obesity and type 2 diabetes, alternative diets including high-protein, high-fat, low-carbohydrate diets have become increasingly popular. The purpose of this review is to discuss potential effects of increased protein intake on glucose metabolism and body weight. Recent intervention trials revealed that, in the short-term, the intake of proteins at the expense of carbohydrates increases satiety and thereby lowers intake of calories. High protein intake augments prandial insulin secretion and might thereby improve glycaemic control in type 2 diabetic patients. On the other hand, epidemiological studies suggest that chronic high dietary protein intake is associated with increased incidence of type 2 diabetes. Furthermore, a short-term increase in plasma amino acid concentrations has been shown to directly induce insulin resistance in skeletal muscle and stimulate endogenous glucose production. Dietary proteins and amino acids are potent modulators of glucose metabolism and might also affect satiety and energy intake. However, due to the lack of well-controlled long-term studies the optimal macronutrient composition for treatment and prevention of obesity and type 2 diabetes is not known.
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The greater prevalence of obesity and the metabolic syndrome in the past 35 y has been attributed to the replacement of sucrose in the food supply with high-fructose corn syrup (HFCS). Two experiments were conducted to determine the effect of solutions containing sucrose, HFCS, or various ratios of glucose to fructose (G:F) on food intake (FI), average appetite (AA), blood glucose (BG), plasma insulin, ghrelin, and uric acid (UA) in men. Sugar solutions (300 kcal/300 mL) were (in %) G20:F80, HFCS 55 (G45:F55), sucrose, and G80:F20 (experiment 1, n = 12) and G20:F80, G35:F65, G50:F50, sucrose, and G80:F20 (experiment 2, n = 19). The controls were a sweet energy-free control (experiment 1) and water (both experiments). Solutions were provided in a repeated-measures design. AA, BG, and FI were measured in all subjects. Hormonal responses and UA were measured in 7 subjects in experiment 2. Measurements were taken from baseline to 75 min. FI was measured at 80 min. Sucrose and HFCS (experiment 1) and sucrose and G50:F50 (experiment 2) had similar effects on all dependent measures. All sugar solutions similarly reduced the AA area under the curve (AUC). FI and plasma UA concentrations were significantly (P < 0.05) lower after high-glucose solutions than after low-glucose solutions. The lower FI was associated with a greater BG AUC (P < 0.05) and smaller AA and ghrelin AUCs (P < 0.01). Insulin and BG AUCs were positively associated (P < 0.001). Sucrose, HFCS, and G50:F50 solutions do not differ significantly in their short-term effects on subjective and physiologic measures of satiety, UA, and FI at a subsequent meal.
Article
Whey protein has potential as a functional food component to contribute to the regulation of body weight by providing satiety signals that affect both short-term and long-term food intake regulation. Because whey is an inexpensive source of high nutritional quality protein, the utilization of whey as a physiologically functional food ingredient for weight management is of current interest. At present, the role of individual whey proteins and peptides in contributing to food intake regulation has not been fully defined. However, Whey protein reduces short-term food intake relative to placebo, carbohydrate and other proteins. Whey protein affects satiation and satiety by the actions of: (1) whey protein fractions per se; (2) bioactive peptides; (3) amino-acids released after digestion; (4) combined action of whey protein and/or peptides and/or amino acids with other milk constituents. Whey ingestion activates many components of the food intake regulatory system. Whey protein is insulinotropic, and whey-born peptides affect the renin-angiotensin system. Therefore whey protein has potential as physiologically functional food component for persons with obesity and its co-morbidities (hypertension, type II diabetes, hyper- and dislipidemia). It remains unclear, however, if the favourable effects of whey on food intake, subjective satiety and intake regulatory mechanisms in humans are obtained from usual serving sizes of dairy products. The effects described have been observed in short-term experiments and when whey is consumed in much higher amounts.
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The influence of calcium and dairy food intake on energy balance is the object of a growing scientific literature. This manuscript presents the information discussed by subject experts during a symposium on calcium and obesity, initially planned to document in a comprehensive manner the role of calcium and dairy food on energy balance and body composition. This manuscript is organized into 13 propositions statements which either resume the presentation of an invited speaker or integrate recent developments in calcium-related obesity research. More specifically, the effects of calcium and dairy consumption on body weight and adiposity level, appetite, weight loss intervention outcome, lipid-lipoprotein profile and the risk to develop metabolic syndrome are discussed together with the metabolic mechanisms proposed to explain these effects. Taken together, the observations presented in this manuscript suggest that calcium and dairy food intake can influence many components