Evidence of enhanced serum amino acid profile but not appetite suppression by dietary glycomacropeptide (GMP): a comparison of dairy whey proteins

Appetite, food intake, and gut hormone responses to glycomacropeptide protein ingestion in older adults: A feasibility, acceptability, and pilot study

Glycomacropeptide (GMP) has a unique amino acid profile which may make less satiating than other dietary proteins. This study assessed the feasibility and likely acceptability of a leucine-enriched GMP drink and determined appetite response in older adults (OA). Thirteen OA (11f; 70 ± 4 years) were recruited for sensory assessments of a leucine-enriched GMP drink when mixed with water and with fruit smoothie, compared with whey protein isolate (WHEY). Participants also partook in a single focus group exploring acceptability to protein and supplementation. Separately, a counterbalanced, double-blind study with twelve OA (8f; 69 ± 3 years) was conducted to determine appetite and gut hormone responses. Fasting subjective appetite was recorded using visual analogue scales and a fasted venous blood sample was collected (to measures acyl-ghrelin, PYY, GLP-1, and CCK) before participants consumed either: GMP protein (27g + 3g leucine, 350 mL water), WHEY (30g, 350 mL water), or water. Participants rested for 240 min, with appetite measures and blood sampling throughout. An ad libitum pasta-based meal was then consumed. Sensory testing revealed low pleasantness rating for GMP in water vs. WHEY (16 ± 14 vs 31 ± 24, p = 0.016). GMP addition to smoothie reduced pleasantness (26 ± 21 vs. 61 ± 29, p = 0.009) and worsened the aroma (46 ± 15 vs. 69 ± 28, p = 0.014). The focus group revealed uncertainty of protein needs and a scepticism of supplements, with preference for food. Gut hormone response did not differ between GMP and WHEY (nAUC for all gut hormones p > 0.05). There was no difference between conditions for lunch ad libitum intake (549 ± 171 kcal, 512 ± 238 kcal, 460 ± 199 kcal for GMP, WHEY, and water, p = 0.175), or for subjective appetite response. Leucine-enriched GMP was not less satiating than WHEY, and low palatability and scepticism of supplements question the likely acceptability of GMP supplementation. Providing trusted nutritional advice and food enrichment/fortification may be preferred strategies for increasing protein intake in OA.

Safety of Beta‐lactoglobulin as a Novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on beta‐lactoglobulin (BLG) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF (≥ 90% w/w dry matter protein) consists of BLG as primary component (≥ 90% of total protein), which is equivalent to BLG present in bovine milk and whey protein isolate (WPI). The NF is produced from bovine whey by crystallisation under acidic or neutral conditions. The NF is proposed to be used as a food ingredient in isotonic and sport drinks, whey powder and milk‐based drinks and similar products, and in food for special medical purposes as defined in Regulation (EU) No 609/2013. The target population is the general population. The highest daily intake of the NF was estimated for children of 3 to < 10 years of age as 667 mg/kg body weight (bw) per day. The NF presents proximate composition and content of essential amino acids similar to those in WPI. The Panel notes that the highest mean and highest 95th percentile daily protein intakes from the NF are below the protein population reference intakes for all population groups. Although a tolerable upper intake level has not been derived for protein, the protein intake from the NF may nevertheless further contribute to an already high dietary protein intake in Europe. The exposure to the reported minerals does not raise concerns. The Panel considers that the consumption of the NF is not nutritionally disadvantageous. No genotoxic concerns were identified from the standard in vitro test battery. No adverse effects were observed in the subchronic toxicity study, up to the highest dose tested, i.e. 1,000 mg NF/kg bw per day. The Panel concludes that the NF is safe under the proposed conditions of use.

Biological, functional and nutritional properties of caseinomacropeptide from sweet whey

Bioactive peptides derived from bovine milk proteins have gained much attention due to their health promoting functions. All over the world, cheese industry generates high volumes of sweet whey that could be used as an alternative source of bioactive peptide in nutraceuticals and food industry. Caseinomacropeptide (CMP) is a bioactive peptide derived from κ-casein by the action of chymosin during cheese manufacturing. CMP consist of two forms which are glycosylated (gCMP) and non-glycosylated (aCMP). The predominant carbohydrate in gCMP is N-acetylneuraminic (sialic acid) which gives functional and biological properties to gCMP. Due to its unique composition and technological characteristics such as wide pH range solubility, emulsifying, gelling, and foaming ability, CMP has received special attention. Therefore, there is an increased interest in researches for isolation and concentration of CMP. However, the isolation and purification methods are not cost-effective. It would be easier to optimize the conditions for isolation, purification, and utilization of CMP in nutraceuticals and food industry through deeper understanding of the effective factors. In this review, the structure of CMP, biological activities, isolation, and purification methods, the factors affecting functional properties and application areas of CMP in food industry are discussed.

Glycomacropeptide: A Bioactive Milk Derivative to Alleviate Metabolic Syndrome Outcomes

Significance: Metabolic syndrome (MetS) represents a cluster of cardiometabolic disorders, which accelerate the risk of developing diabetes, nonalcoholic fatty liver disease, and cardiovascular disorders such as atherosclerosis. Oxidative stress (OxS) and inflammation contribute to insulin resistance (IR) that greatly promotes the clinical manifestations of MetS components. Given the growing prevalence of this multifactorial condition, its alerting comorbidities, and the absence of specific drugs for treatment, there is an urgent need of prospecting for alternative nutraceutics as effective therapeutic agents for MetS. Recent Advances: There is a renewed interest in bioactive peptides derived from human and bovine milk proteins given their high potential in magnifying health benefits. Special attention has been paid to glycomacropeptide (GMP), a bioactive and soluble derivative from casein and milk whey, because of the wide range of its health-promoting functions perceived in the MetS and related complications. Critical Issues: In the present review, the challenging issue relative to clinical utility of GMP in improving MetS outcomes will be critically reported. Its importance in alleviating obesity, OxS, inflammation, IR, dyslipidemia, and hypertension will be underlined. The mechanisms of action will be analyzed, and the various gaps of knowledge in this area will be specified. Future Directions: Valuable data from cellular, preclinical, and clinical investigations have emphasized the preventive and therapeutic actions of GMP toward the MetS. However, additional efforts are needed to support its proofs of principle and causative relationship to translate its concept into the clinic. Antioxid. Redox Signal. 34, 201-222.

Nutrition, Microbiota and Role of Gut-Brain Axis in Subjects with Phenylketonuria (PKU): A Review

The composition and functioning of the gut microbiota, the complex population of microorganisms residing in the intestine, is strongly affected by endogenous and exogenous factors, among which diet is key. Important perturbations of the microbiota have been observed to contribute to disease risk, as in the case of neurological disorders, inflammatory bowel disease, obesity, diabetes, cardiovascular disease, among others. Although mechanisms are not fully clarified, nutrients interacting with the microbiota are thought to affect host metabolism, immune response or disrupt the protective functions of the intestinal barrier. Similarly, key intermediaries, whose presence may be strongly influenced by dietary habits, sustain the communication along the gut-brain-axis, influencing brain functions in the same way as the brain influences gut activity. Due to the role of diet in the modulation of the microbiota, its composition is of high interest in inherited errors of metabolism (IEMs) and may reveal an appealing therapeutic target. In IEMs, for example in phenylketonuria (PKU), since part of the therapeutic intervention is based on chronic or life-long tailored dietetic regimens, important variations of the microbial diversity or relative abundance have been observed. A holistic approach, including a healthy composition of the microbiota, is recommended to modulate host metabolism and affected neurological functions.

Casein glycomacropeptide is well tolerated in healthy adults and changes neither high-sensitive C-reactive protein, gut microbiota nor faecal butyrate: a restricted randomised trial

Casein glycomacropeptide (CGMP) is a bioactive milk-derived peptide with potential anti-inflammatory effects. Animal studies suggest that CGMP may work by altering gut microbiota composition and enhancing butyrate production. Its effects on intestinal homoeostasis, microbiota and metabolites in humans are unknown. The aim of the present study was to assess both the intestinal and systemic immunomodulatory effects of orally ingested CGMP. We hypothesised that daily oral CGMP intake would reduce high-sensitive C-reactive protein (hsCRP) in healthy adults. In a single-centre limited but randomised, double-blinded, reference-controlled study, we compared the effects of a 4-week intervention of either 25 g of oral powder-based chocolate-flavoured CGMP or a reference drink. We included twenty-four healthy adults who all completed the study. CGMP had no systemic or intestinal immunomodulatory effects compared with a reference drink, with regard to either hsCRP or faecal calprotectin level, faecal microbiota composition or faecal SCFA content. CGMP ingestion did not affect satiety or body weight, and it caused no severe adverse events. The palatability of CGMP was acceptable, and adherence was high. CGMP did not induce or change gastrointestinal symptoms. In conclusion, we found no immunomodulatory effects of CGMP in healthy adults. In a minor group of healthy adults, oral ingestion of 25 g of CGMP during 4 weeks was safe, well tolerated, had acceptable palatability and was without any effects on body weight.

The Impact of the Use of Glycomacropeptide on Satiety and Dietary Intake in Phenylketonuria

Protein is the most satiating macronutrient, increasing secretion of gastrointestinal hormones and diet induced thermogenesis. In phenylketonuria (PKU), natural protein is restricted with approximately 80% of intake supplied by a synthetic protein source, which may alter satiety response. Casein glycomacropeptide (CGMP-AA), a carbohydrate containing peptide and alternative protein substitute to amino acids (AA), may enhance satiety mediated by its bioactive properties. Aim: In a three-year longitudinal; prospective study, the effect of AA and two different amounts of CGMP-AA (CGMP-AA only (CGMP100) and a combination of CGMP-AA and AA (CGMP50) on satiety, weight and body mass index (BMI) were compared. Methods: 48 children with PKU completed the study. Median ages of children were: CGMP100; (n = 13), 9.2 years; CGMP50; (n = 16), 7.3 years; and AA (n = 19), 11.1 years. Semi-quantitative dietary assessments and anthropometry (weight, height and BMI) were measured every three months. Results: The macronutrient contribution to total energy intake from protein, carbohydrate and fat was similar across the groups. Adjusting for age and gender, no differences in energy intake, weight, BMI, incidence of overweight or obesity was apparent between the groups. Conclusion: In this three-year longitudinal study, there was no indication to support a relationship between CGMP and satiety, as evidenced by decreased energy intake, thereby preventing overweight or obesity. Satiety is a complex multi-system process that is not fully understood.

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

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

Effects of whey protein and its two major protein components on satiety and food intake in normal-weight women

Protein is the most satiating macronutrient and is source dependent, with whey protein thought to be particularly satiating. The purported satiating effect of whey protein may be due to the unique mixture of proteins in whey or to the major constituent individual proteins (β-lactoglobulin and α-lactalbumin). The objective of the study was to compare the effects of isoenergetic (~2100kJ, ~500kcal) preload meals enriched (~50g protein) with either whey protein isolate (WP), β-lactoglobulin (BL) isolate or α-lactalbumin (AL) isolate, on food intake at an ad libitum test meal 120min later and subjective ratings of appetite (hunger, desire to eat, prospective food consumption and fullness) using visual analogue scales (VAS). Twenty adult normal-weight women (mean age 24.2±0.8years; mean BMI 22.7±0.4kg/m²) participated in the study which used a single-blind completely randomised block design, where each subject consumed each of the three preload meals. Energy intake at the ad libitum test meal and total energy intakes (preload+test meal) did not differ between the three preload meals (p>0.05). There were no significant differences observed for the VAS scores and net incremental area under the curve (net iAUC) during the 120min following consumption of the three preload meals for subjective ratings of appetite (p>0.05). The findings show that the satiating effect of whey protein was similar to that of BL or AL individually and suggest that the major whey protein components BL and AL do not mediate the satiating effect of whey protein. The present human trial was registered with the Australian New Zealand Clinical Trials Registry (www.anzctr.org.au) as ACTRN12615000344594.

Small particle size lipid emulsions, satiety and energy intake in lean men

Lipid emulsions have been proposed to suppress hunger and food intake. Whilst there is no consensus on optimal structural properties or mechanism of action, small particle size (small-PS) stable emulsions may have greatest efficacy. Fabuless®, a commercial lipid emulsion reported in some studies to decrease energy intake (EI), is a small-PS, 'hard' fat emulsion comprising highly saturated palm oil base (PS, 82nm). To determine whether small-PS dairy lipid emulsions can enhance satiety, firstly, we investigated 2 'soft' fat dairy emulsions generated using dairy and soy emulsifying agents (PS, 114nm and 121nm) and a non-emulsified dairy control. Secondly, we investigated a small-PS palmolein based 'hard' fat emulsion (fractionated palm oil, PS, 104nm) and non-emulsified control. This was a 6 arm, randomized, cross-over study in 18 lean men, with test lipids delivered in a breakfast meal: (i) Fabuless® emulsion (F_EM); (ii) dairy emulsion with dairy emulsifier (DE_DE); (iii) dairy emulsion with soy lecithin emulsifier (DE_SE); (iv) dairy control (DC_ON); (v) palmolein emulsion with dairy emulsifier (PE_DE); (vi) palmolein control (PC_ON). Participants rated postprandial appetite sensations using visual analogue scales (VAS), and ad libitum energy intake (EI) was measured at a lunch meal 3.5h later. Dairy lipid emulsions did not significantly alter satiety ratings or change EI relative to dairy control (DE_DE, 4035kJ; DE_SE, 3904kJ; DC_ON, 3985kJ; P>0.05) nor did palm oil based emulsion relative to non-emulsified control (PE_DE, 3902 kJ; PC_ON, 3973kJ; P>0.05). There was no evidence that small-PS dairy lipid emulsions or commercial Fabuless altered short-term appetite or food intake in lean adults.

Prevention of type 2 diabetes through lifestyle modification: is there a role for higher-protein diets?

Type 2 diabetes (T2D) incidence is increasing worldwide, driven by a rapidly changing environment and lifestyle and increasing rates of overweight and obesity. Prevention of diabetes is key and is most likely achieved through prevention of weight gain and/or successful long-term weight loss maintenance. Weight loss is readily achievable but there is considerable challenge in maintaining that weight loss over the long term. Lower-fat carbohydrate-based diets are widely used for T2D prevention. This is supported primarily by 3 successful long-term interventions, the US Diabetes Prevention Program, the Finnish Diabetes Prevention Study, and the Chinese Da Qing Study, but evidence is building in support of novel higher-protein (>20% of energy) diets for successful weight loss maintenance and prevention of T2D. Higher-protein diets have the advantage of having relatively low energy density, aiding longer-term appetite suppression, and preserving lean body mass, all central to successful weight loss and prevention of weight regain. Here, we review the carbohydrate-based intervention trials and present mechanistic evidence in support of increased dietary protein for weight loss maintenance and a possible novel role in prevention of dysglycemia and T2D.

Bioactive properties of milk proteins in humans: A review

Many studies have demonstrated that milk protein consumption has benefits in terms of promoting human health. This review assesses the intervention studies which have evaluated potential health enhancing effects in humans following the ingestion of milk proteins. The impact of milk protein ingestion has been studied to asses their satiating, hypotensive, antimicrobial, anti-inflammatory, anticancer, antioxidant and insulinotropic properties as well as their impact on morphological modifications (e.g., muscle and fat mass) in humans. Consistent health promoting effects appear to have been observed in certain instances (i.e., muscle protein synthesis, insulinotropic and hypotensive activity). However, controversial outcomes have also been reported (i.e., antimicrobial, anti-inflammatory, anticancer and antioxidant properties). Several factors including interindividual differences, the timing of protein ingestion as well as the potency of the active components may explain these differences. In addition, processing conditions have been reported, in certain instances, to affect milk protein structure and therefore modify their bioactive potential. It is thought that the health promoting properties of milk proteins are linked to the release of bioactive peptides (BAPs) during gastrointestinal digestion. There is a need for further research to develop a more in-depth understanding on the possible mechanisms involved in the observed physiological effects. In addition, more carefully controlled and appropriately powered human intervention studies are required to demonstrate the health enhancing properties of milk proteins in humans.

Glycomacropeptide is a prebiotic that reduces Desulfovibrio bacteria, increases cecal short-chain fatty acids, and is anti-inflammatory in mice

Glycomacropeptide (GMP) is a 64-amino acid (AA) glycophosphopeptide with application to the nutritional management of phenylketonuria (PKU), obesity, and inflammatory bowel disease (IBD). GMP is a putative prebiotic based on extensive glycosylation with sialic acid, galactose, and galactosamine. Our objective was to determine the prebiotic properties of GMP by characterizing cecal and fecal microbiota populations, short-chain fatty acids (SCFA), and immune responses. Weanling PKU (Pah(enu2)) and wild-type (WT) C57Bl/6 mice were fed isoenergetic AA, GMP, or casein diets for 8 wk. The cecal content and feces were collected for microbial DNA extraction to perform 16S microbiota analysis by Ion Torrent PGM sequencing. SCFA were determined by gas chromatography, plasma cytokines via a Bio-Plex Pro assay, and splenocyte T cell populations by flow cytometry. Changes in cecal and fecal microbiota are primarily diet dependent. The GMP diet resulted in a reduction from 30-35 to 7% in Proteobacteria, genera Desulfovibrio, in both WT and PKU mice with genotype-dependent changes in Bacteroidetes or Firmicutes. Cecal concentrations of the SCFA acetate, propionate, and butyrate were increased with GMP. The percentage of stimulated spleen cells producing interferon-γ (IFN-γ) was significantly reduced in mice fed GMP compared with casein. In summary, plasma concentrations of IFN-γ, TNF-α, IL-1β, and IL-2 were reduced in mice fed GMP. GMP is a prebiotic based on reduction in Desulfovibrio, increased SCFA, and lower indexes of inflammation compared with casein and AA diets in mice. Functional foods made with GMP may be beneficial in the management of PKU, obesity, and IBD.

Postprandial effects of a polyphenolic grape extract (PGE) supplement on appetite and food intake: a randomised dose-comparison trial

Background

There is recent evidence that glucose delivered to the distal small intestine (SI) may stimulate the ileal brake and inhibit appetite. High polyphenolic grape extract (PGE) has been shown to inhibit α-amylase and α-glucosidase activity, two key enzymes required for starch digestion, in vitro. It is hypothesised to slow digestion and absorption of starch in the proximal SI such that glucose may be delivered distally into the ileum and suppress appetite. This study investigated the safety and efficacy of a PGE supplement, delivered within a capsule and consumed with a high-starch breakfast, on appetite ratings and ad libitum energy intake (EI) at a subsequent lunch meal.

Methods

Twenty healthy, non-obese (BMI 18–28 kg/m²) male volunteers participated in a randomised, double blind, placebo controlled, three arm, cross-over study. Participants were administered (i) low dose PGE₅₀₀ (500 mg), (ii) high dose PGE₁₅₀₀ (1500 mg), and (iii) matched placebo with a 2MJ high-starch breakfast (white bread); followed 3 h later by a single item buffet-style lunch meal (pasta and meat sauce). Outcome variables were feelings of hunger, fullness, prospective thoughts of food (TOF) and satisfaction assessed using visual analogue scales (VAS); and ad lib energy and macronutrient intake at the lunch meal.

Results

There was no detectable effect of PGE₅₀₀ or PGE₁₅₀₀ compared with placebo (all, time*supplement interaction, P > 0.05) on VAS-assessed hunger, fullness, TOF or satisfaction. There was also no evidence that PGE significantly altered ad lib energy or macronutrient intake at the lunch meal relative to placebo (P > 0.05). EI following PGE₅₀₀ was +164 kJ higher than placebo (+5.3 %, P > 0.05); and EI following PGE₁₅₀₀was −51 kJ lower than placebo (−1.7 %, P > 0.05).

Conclusions

Whilst well tolerated, there was no evidence that encapsulated low dose PGE₅₀₀ or high dose PGE₁₅₀₀ consumed with a high starch breakfast meal altered postprandial hunger, fullness, TOF or satisfaction relative to a matched placebo. Nor was there evidence that either dose altered ad lib energy or macronutrient intake at an outcome meal.

Trial registration

ACTRN12614000041651

No evidence of enhanced satiety following whey protein- or sucrose-enriched water beverages: a dose response trial in overweight women

BACKGROUND/OBJECTIVES

To compare the effect of low-dose whey protein-enriched and sucrose-enriched water beverages on postprandial satiety and energy intake.

SUBJECTS/METHODS

Sixty overweight and obese women were given water-based protein and carbohydrate (CHO) beverages or placebo on six different occasions in a double-blind, randomised cross-over study. The beverages were 2 (178 kJ) and 4% (348 kJ) protein-enriched water (Clear Protein8855), 2 (157 kJ), 4 (314 kJ) and 10% (785 kJ) sucrose-enriched water, and a sweetened water control. Beverages were matched for volume, colour, flavour and sweetness. A standardised evening meal was provided before each study day and a standardised breakfast upon arrival at the clinic at 0900 hours. The beverage preload was given midmorning at 1100 hours, and an ad libitum outcome lunch meal at 1300 hours. Subjective appetitive responses were recorded through the day until 1500 hours using visual analogue scales.

RESULTS

Fifty-five participants completed all six beverage conditions. Neither protein nor sucrose preloads decreased any of hunger, fullness, thoughts of food or satisfaction when compared with the sweetened water control beverage (all, P>0.05). There was also no significant effect on ad libitum energy or macronutrient intake at the outcome meal (P>0.05), with no compensation for the energy consumed within the preload beverages.

CONCLUSIONS

There was no evidence of increased postprandial satiety or compensation for energy content at an outcome lunch meal when a water beverage was supplemented with up to 4% (w/w) whey protein or 10% (w/w) sucrose, in a group of overweight but unrestrained young and middle-aged women.

In vitrotransport and satiety of a beta-lactoglobulin dipeptide and beta-casomorphin-7 and its metabolites

In vitrotransport of β-CM7 occurs through rapid hydrolysis into three peptide metabolites that transport at variable rates.

Lipids, CHOs, proteins: can all macronutrients put a 'brake' on eating?

The gastrointestinal (GI) tract and specifically the most distal part of the small intestine, the ileum, has become a renewed focus of interest for mechanisms targeting appetite suppression. The 'ileal brake' is stimulated when energy-containing nutrients are delivered beyond the duodenum and jejunum and into the ileum, and is named for the feedback loop which slows or 'brakes' gastric emptying and duodeno-jejunal motility. More recently it has been hypothesized that the ileal brake also promotes secretion of satiety-enhancing GI peptides and suppresses hunger, placing a 'brake' on food intake. Postprandial delivery of macronutrients to the ileum, other than unavailable carbohydrates (CHO) which bypass absorption in the small intestine en route to fermentation in the large bowel, is an uncommon event and hence this brake mechanism is rarely activated following a meal. However the ability to place a 'brake' on food intake through delivery of protected nutrients to the ileum is both intriguing and challenging. This review summarizes the current clinical and experimental evidence for activation of the ileal brake by the three food macronutrients, with emphasis on eating behavior and satiety as well as GI function. While clinical studies have shown that exposure of the ileum to lipids, CHOs and proteins may activate GI components of the ileal brake, such as decreased gut motility, gastric emptying and secretion of GI peptides, there is less evidence as yet to support a causal relationship between activation of the GI brake by these macronutrients and the suppression of food intake. The predominance of evidence for an ileal brake on eating comes from lipid studies, where direct lipid infusion into the ileum suppresses both hunger and food intake. Outcomes from oral feeding studies are less conclusive with no evidence that 'protected' lipids have been successfully delivered into the ileum in order to trigger the brake. Whether CHO or protein may induce the ileal brake and suppress food intake has to date been little investigated, although both clearly have GI mediated effects. This review provides an overview of the mechanisms and mediators of activation of the ileal brake and assesses whether it may play an important role in appetite suppression.

Milk protein for improved metabolic health: a review of the evidence

Epidemiological evidence shows that consumption of dairy products is associated with decreased prevalence of metabolic related disorders, whilst evidence from experimental studies points towards dairy protein as a dietary component which may aid prevention of type 2 diabetes (T2DM). Poor metabolic health is a common characteristic of overweight, obesity and aging, and is the forerunner of T2DM and cardiovascular disease (CVD), and an ever increasing global health issue. Progressive loss of metabolic control is evident from a blunting of carbohydrate, fat and protein metabolism, which is commonly manifested through decreased insulin sensitivity, inadequate glucose and lipid control, accompanied by a pro-inflammatory environment and hypertension. Adverse physiological changes such as excess visceral adipose tissue deposition and expansion, lipid overspill and infiltration into liver, muscle and other organs, and sarcopaenia or degenerative loss of skeletal muscle mass and function all underpin this adverse profile. ‘Sarcobesity’ and sarcopaenic diabetes are rapidly growing health issues. As well as through direct mechanisms, dairy protein may indirectly improve metabolic health by aiding loss of body weight and fat mass through enhanced satiety, whilst promoting skeletal muscle growth and function through anabolic effects of dairy protein-derived branch chain amino acids (BCAAs). BCAAs enhance muscle protein synthesis, lean body mass and skeletal muscle metabolic function. The composition and processing of dairy protein has an impact on digestion, absorption, BCAA kinetics and function, hence the optimisation of dairy protein composition through selection and combination of specific protein components in milk may provide a way to maximize benefits for metabolic health.