Protein source, quantity, and time of consumption determine the effect of proteins on short-term food intake in young men

Dietary proteins from various sources have different effects on short-term food intake and intestinal hormone secretion

Besides their nutritional role, proteins are recognized for their ability to regulate both short- and long-term energy homeostasis. However, studies investigating the effects of proteins based on their quality and origin remain limited and often lack comparability. Nonetheless, existing research consistently underscores the influence of proteins on food intake regulation. Additionally, digested proteins promote satiety by stimulating the secretion of intestinal hormones. This study aimed to compare the effects of proteins from different origins (hemoglobin, caseins, ovalbumin, whey proteins, fish gelatin, pea proteins and gluten proteins) on short-term food intake using Wistar rats in metabolic cages. Proteins were then digested using in vitro static INFOGEST protocol to assess their effects on intestinal hormone secretion using STC-1 cells. The results revealed distinct impacts of these proteins on short-term food intake, respiratory exchange ratio, but also on GLP-1 and CCK secretion. This study demonstrates the impact of various proteins on energy homeostasis by affecting the regulation of short-term food intake, which correlates with the modulation of intestinal hormone secretion. The findings also emphasize the role of protein origin in these mechanisms, with whey, pea, and gluten emerging as the most effective. Differences in satiety among proteins can be attributed to variations in digestibility rates and effects on intestinal hormone secretion, indicating that dietary proteins regulate food intake in a manner dependent on both their nature and origin.

Variations in Bovine Milk Proteins and Processing Conditions and Their Effect on Protein Digestibility in Humans: A Review of In Vivo and In Vitro Studies

Bovine milk proteins account for 10% of the global protein supply, which justifies the importance of thoroughly understanding their digestive processes. Extensive research on digestion is being conducted both in vivo and in vitro. However, interpretations and comparisons across different studies require a thorough understanding of the methodologies used. Both the rate and extent of milk protein digestion can be affected by several intrinsic and extrinsic factors with potential implications for overall digestibility and physiological responses. Among intrinsic factors, the impact of genetic variants in native milk proteins has emerged as a growing research area. To these, further complexity is added by the processing conditions frequently applied to milk prior to consumption. The main aim of this work is to provide an overview of the current knowledge on the impact of variations in milk protein profiles (particularly whey: casein ratio and protein polymorphisms), the treatments applied during processing (pasteurisation, homogenisation) and consumption (temperature changes) on protein digestion. To support the interpretation of the current literature, this manuscript also presents a historical perspective into research in this field and summarizes the protocols that are most frequently used, presently, on in vitro digestion studies.

Manipulation of Post-Prandial Hyperglycaemia in Type 2 Diabetes: An Update for Practitioners

This review paper explores post-prandial glycemia in type 2 diabetes. Post-prandial glycemia is defined as the period of blood glucose excursion from immediately after the ingestion of food or drink to 4 to 6 hours after the end of the meal. Post-prandial hyperglycemia is an independent risk factor for cardiovascular disease with glucose "excursions" being more strongly associated with markers of oxidative stress than the fasting or pre-prandial glucose level. High blood glucose is a major promoter of enhanced free radical production and is associated with the onset and progression of type 2 diabetes. Oxidative stress impairs insulin action creating a vicious cycle where repeated post-prandial glucose spikes are key drivers in the pathogenesis of the vascular complications of type 2 diabetes, both microvascular and macrovascular. Some authors suggest post-prandial hyperglycemia is the major cause of death in type 2 diabetes. Proper management of post-prandial hyperglycemia could yield up to a 35% cut in overall cardiovascular events, and a 64% cut in myocardial infarction. The benefits of managing post-prandial hyperglycemia are similar in magnitude to those seen in type 2 diabetes patients receiving secondary prevention with statins - prevention which today is regarded as fundamental by all practitioners. Given all the evidence surrounding the impact of post-prandial glycemia on overall outcome, it is imperative that any considered strategy for the management of type 2 diabetes should include optimum dietary, pharma, and lifestyle interventions that address glucose excursion. Achieving a low post-prandial glucose response is key to prevention and progression of type 2 diabetes and cardiometabolic diseases. Further, such therapeutic interventions should be sustainable and must benefit patients in the short and long term with the minimum of intrusion and side effects. This paper reviews the current literature around dietary manipulation of post-prandial hyperglycemia, including novel approaches. A great deal of further work is required to optimize and standardize the dietary management of post-prandial glycemia in type 2 diabetes, including consideration of novel approaches that show great promise.

Impacts of dietary animal and plant protein on weight and glycemic control in health, obesity and type 2 diabetes: friend or foe?

It is well established that high-protein diets (i.e. ~25-30% of energy intake from protein) provide benefits for achieving weight loss, and subsequent weight maintenance, in individuals with obesity, and improve glycemic control in type 2 diabetes (T2D). These effects may be attributable to the superior satiating property of protein, at least in part, through stimulation of both gastrointestinal (GI) mechanisms by protein, involving GI hormone release and slowing of gastric emptying, as well as post-absorptive mechanisms facilitated by circulating amino acids. In contrast, there is evidence that the beneficial effects of greater protein intake on body weight and glycemia may only be sustained for 6-12 months. While both suboptimal dietary compliance and metabolic adaptation, as well as substantial limitations in the design of longer-term studies are all likely to contribute to this contradiction, the source of dietary protein (i.e. animal vs. plant) has received inappropriately little attention. This issue has been highlighted by outcomes of recent epidemiological studies indicating that long-term consumption of animal-based protein may have adverse effects in relation to the development of obesity and T2D, while plant-based protein showed either protective or neutral effects. This review examines information relating to the effects of dietary protein on appetite, energy intake and postprandial glycemia, and the relevant GI functions, as reported in acute, intermediate- and long-term studies in humans. We also evaluate knowledge relating to the relevance of the dietary protein source, specifically animal or plant, to the prevention, and management, of obesity and T2D.

Comparative evaluation of milk proteins and oil-seed-cake-derived proteins extracted by chemical and biological methods for obesity management

BACKGROUND

In light of the exponential rise in global population, there is a critical requirement to reduce food waste on a global scale. According to studies, agricultural wastes such as oil-seed cakes offer great nutritional value. Acid precipitation (A) and alkaline extraction methods (traditional methods) were used to extract protein from oil-seed cakes; however, both procedures are linked to decreased protein quality and quantity, which prompted the development of a novel strategy known as the biological/microbial/probiotic (B) method. Therefore, the present study aimed to highlight the optimal way of protein extraction from oil-seed cakes and the effect of extraction methods on protein efficacy against obesity. The outcomes were also compared with milk proteins.

RESULTS

In vitro study provided evidence that proteins from both sources (plant and milk) suppressed adipogenesis and stimulated adipolysis in 3T3L-1 cells. For the in vivo study, mice were fed with different protein extracts: soya protein preparation (SPP), ground protein preparation (GPP), whey protein (WP) and casein protein (CP) containing 40% of their calories as fat. Body weight decreased significantly in all the rats except CP-fed rats. Body mass index, atherogenic index, plasma triglyceride and very-low-density lipoprotein cholesterol level decreased significantly in all the groups in comparison to the model group (high-fat-diet group), but the decrease was more pronounced in plant proteins than milk proteins. In hepatocytes, the expression of fasting-induced adipose factor, carnitine palmitoyltransferase I and peroxisome proliferator-activated receptor α genes was increased significantly in SPP-fed groups. Adiponectin gene expression was upregulated significantly in visceral fat tissue in groups fed SPP-B, GPP-A and CP, whereas leptin gene was downregulated significantly in all groups except SPP-A.

CONCLUSION

This study demonstrates that SPP-B showed the most effective anti-obesity property, followed by WP. Additionally, we found that the biological precipitation approach produced better outcomes for plant proteins isolated from oil-seed cakes than the acid precipitation method. © 2023 Society of Chemical Industry.

The effect of source of protein fed during pregnancy and lactation on the development of characteristics of metabolic syndrome in male offspring of obese Wistar rats

Gestational obesity has major negative impacts on both mothers and their offspring. More than two-thirds of women of reproductive age in the United States are overweight and/or obese. We previously reported that the source of protein in the maternal diet influences the phenotype of offspring born to normal-weight dams. However, whether it has the same effect in obese mothers was unclear. The casein- and soya protein-based diets were fed to obese pregnant Wistar rats and compared for their effects on characteristics of the metabolic syndrome in male offspring. Dams randomized to either a casein (CD) or soya protein (SD) diet (n 12). Pups were weaned to either a CD or SD for 16 weeks. Offspring of SD dams had higher birthweight (P < 0⋅01). Glucose metabolism was not altered at birth but fasting blood glucose (FBG) (P < 0⋅02), insulin (P < 0⋅0002), insulin/glucose ratio (P < 0⋅03), and HOMA-IR index (P < 0⋅0002) were higher in offspring of SD dams at week 17. The pulse rate was higher in dams (P < 0⋅03). Food intake and body weight of offspring were affected by interactive effects of time and dams' diet (P < 0⋅05). Food intake was not influenced by maternal diet, but it was higher in pups weaned to SD dams (P < 0⋅03) The results of this study indicate that although the source of protein in the maternal diet is still an influencing factor in the outcome of the pregnancy in obese mothers, gestational obesity may mask this effect possibly by imposing general detrimental effects on measured parameters regardless of the source of protein in maternal diet.

Protein Source Influences Acute Appetite and Satiety but not Subsequent Food Intake in Healthy Adults

BACKGROUND

Although current recommendations encourage plant-based dietary patterns, data is limited as to whether the equivalent substitution of animal-based protein-rich foods with plant-based versions impacts ingestive behavior.

OBJECTIVE

To compare higher-protein preloads, varying in protein source, on appetite, satiety, and subsequent energy intake.

METHODS

Thirty-two adults (Age: 25±1y; Body Mass Index (BMI): 24.2±0.5kg/m) randomly consumed 250kcal, protein-preload beverages (24g protein), varying in protein source (whey, soy, pea protein isolates (WHEY, SOY, PEA) or micellar casein (CAS)) each morning for 3 acclimation days/preload. On day 4, participants completed a 4-h clinical testing day in which the respective preload was consumed followed by blood sampling and questionnaires every 30min for appetite and satiety. An ad libitum lunch was provided 4-h post-preload. On day 5, participants consumed the respective preload at home followed by an ad libitum breakfast 30min afterwards. For normally-distributed data, repeated-measures analysis of variance (ANOVA) or Friedman non-parametric test were utilized to compare main effects of protein source on study outcomes. Post-hoc pairwise comparisons using least significant differences (LSD) were then performed.

RESULTS

CAS (-3330±690mm*240min) and PEA (-2840±930mm*240min) reduced 4-h appetite vs. SOY (-1440±936mm*240min; both, P<0.05). WHEY was not different (-2290±930mm*240min). CAS (3520±84pg/ml*240min) and PEA (3860±864pg/ml*240min) increased 4-h PYY concentrations vs. SOY (2200±869pg/ml*240min; both, P<0.05). WHEY was not different (3870±932pg/ml*240 min). No differences in ad libitum energy intake were observed.

CONCLUSIONS

CAS and PEA, but not WHEY, elicited greater acute changes in appetite and satiety vs. SOY in healthy adults, supporting that not all protein sources are equivalent. This trial is registered at clinicaltrials.gov (NCT03154606).

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

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

Effects of the maize-derived protein zein, and the milk proteins casein, whey, and α-lactalbumin, on subjective measures of satiety and food intake in normal-weight young men

Protein is considered to be the most satiating food macronutrient and the satiating effect may be dependent on the source of the protein. The maize-derived protein zein and milk protein casein have been shown previously to lower stomach emptying rate more than dairy whey protein, but the effect of zein on satiety has not been evaluated. The objective was to compare the satiating effects of zein and casein, with whey protein and its protein component α-lactalbumin. The study was a randomised crossover design with thirteen normal-weight men (mean age 27.8 years and mean BMI 24.4 kg/m2) consuming isoenergetic (∼4000 kJ, ∼990 kcal) preload mixed meals enriched with Zein, Casein, whey protein isolate (Whey), α-lactalbumin (ALac), or maltodextrin carbohydrate (Carb). Consumption of an ad libitum standardised test meal of chicken fried rice and water provided 360 min following ingestion of the preload meal was measured, and subjective feelings of appetite (hunger, fullness, desire to eat, and prospective food consumption) were assessed using 100-mm visual analogue scales (VAS). There were no differences among the five preload mixed meals in the amount of chicken fried rice consumed at the ad libitum test meal (mean ± sem: 531.6 ± 35.0 g, p = 0.47) or total (preload + test meal) energy intakes (mean ± sem: 5780.5 ± 146.0 kJ, p = 0.29). The subjective VAS appetite ratings and total area under the curve responses for hunger, fullness, desire to eat, and prospective food consumption, were not different following consumption of all five preload mixed meals (p > 0.05). The findings indicate that the effects of zein and casein on satiety were not different from the satiating effects of whey protein and α-lactalbumin.

Identification of Genetic Effects of ACADVL and IRF6 Genes with Milk Production Traits of Holstein Cattle in China

With the development of high-throughput sequencing, RNA sequencing has been widely used in the identification of candidate genes for complex traits in livestock, and the functional genes and mutations with large genetic effects on milk production traits can provide molecular information for marker-assisted selection to increase the selection accuracy and accelerate genetic gain in dairy cattle. Our previous study on the liver transcriptome of Holstein cows found that acyl-CoA dehydrogenase (ACADVL) and interferon regulatory factor 6 (IRF6) are differentially expressed between dry and peak lactation periods, as well as that they are involved in lipid metabolism and the proliferation and differentiation of mammary epithelial cells. Thus, the two genes were considered candidates for milk traits. Hence, this study further collected 1186 Holstein cows from 110 sire families to investigate their genetic associations with milk yield and composition traits. By resequencing the entire exons and 2000 bp of the 5' and 3' flanking regions of the two genes, we identified eight SNPs in ACADVL and eight SNPs in IRF6. Subsequent single-locus association analyses showed that the eight SNPs in ACADVL were all significantly associated with milk fat yield, fat percentage, and protein yield (p values ≤ 0.0001-0.0414), and the eight SNPs in IRF6 were associated with milk, fat, and protein yields in the first or second lactation (p values ≤ 0.0001-0.0467). Using Haploview 4.2, one haplotype block with eight of the SNPs in ACADVL (D' = 0.99-1.00) and two haplotype blocks in IRF6 with three of the SNPs in each were observed (D' = 0.98-1.00). Similarly, the haplotype combinations of ACADVL were significantly associated with milk yield, fat percentage, fat yield, and protein yield in the two lactations (p values ≤ 0.0001-0.0125), and those of IRF6 were associated with five milk traits (p values ≤ 0.0001-0.0263). Furthermore, with the JASPAR software, it was predicted that the SNPs 19:g.26933503T>C in ACADVL and 16:g.73501985G>A in IRF6 changed the transcription factor binding sites of ZEB1, PLAGL2, and RHOXF1, implying their impacts on the expressions of the corresponding genes. Our findings demonstrated that the ACADVL and IRF6 genes have significant genetic effects on milk yield and composition traits, and the valuable SNPs might be used as genetic markers for genomic selection programs in dairy cattle.

The acute effects of insect vs. beef-derived protein on postprandial plasma aminoacidemia, appetite hormones, appetite sensations, and energy intake in healthy young men

BACKGROUND/OBJECTIVES

The purpose of this study was to evaluate the acute effects of ingesting beef- and insect-derived protein on postprandial plasma amino acid and appetite hormone concentrations, appetite sensations, and ad libitum energy intake.

SUBJECTS/METHODS

In a randomized, double-blind, crossover study, 20 young men (23 (SD: 4) y) completed two trials during which arterialized blood samples and VAS questionnaires were collected at baseline, and over 300-min after ingestion of beverages with similar energy and macronutrient content containing 25 g beef- or insect-derived (cricket) protein. Blood samples were analyzed for plasma amino acid and appetite hormone concentrations, while VAS questionnaires were applied to assess appetite sensations. After each trial, an ad libitum meal was immediately provided to assess energy intake.

RESULTS

Adjusted mean postprandial incremental area under the curve (iAUC) was greater for cricket vs. beef-derived protein for plasma leucine, branched-chain amino acid, and essential amino acid concentrations (all P < 0.0001). Adjusted mean postprandial iAUC for hunger was lower following beef (-3030 (SE: 860)) vs. cricket-derived (-1197 (SE: 525)) protein (Difference: -1833 (95% CI: -3358, -308); P = 0.02), but was not different for other appetite sensations or appetite hormones (all P > 0.05). Adjusted mean ad libitum energy intake was 4072 (SE: 292) and 4408 (SE: 316) kJ following beef- and cricket-derived protein (Difference: -336 (95% CI: -992, 320); P = 0.30).

CONCLUSION

Acute ingestion of cricket and beef-derived protein leads to differences in postprandial plasma amino acid concentrations, but elicits similar effects on appetite hormones, appetite sensations, and ad libitum energy intake in young men.

Effect of an Acute Insect Preload vs. an Almond Preload on Energy Intake, Subjective Food Consumption and Intestinal Health in Healthy Young Adults

Protein is considered the most satiating macronutrient, and its effect on satiety and food intake is source-dependent. For the first time, we compared the effect of the administration of an insect or almond preload, both containing 20 g of protein, on appetite and food intake in human subjects. Participants consumed both foods and a vehicle as a liquid preload on three separate days. They were then offered a breakfast and lunch buffet meal at which food intake was measured. Visual analogue scale (VAS) questionnaires were completed following the three preloads to assess appetite and other sensations. At breakfast, reduced energy intake was observed for both preloads compared with vehicle. At lunch, food intake only differed in the insect group, which consumed more than the vehicle. Insect preload increased the total amount of protein ingested with a slight increase in total energy consumed, differently than almond, which significantly increased total protein and energy consumed. There was no correlation between indigestion-sensation ratings and food intake. Moreover, the insect preload resulted in lower sleepiness and tiredness ratings compared with the almond preload. Thus, insect-derived protein may be suitable as a safe ingredient for snacks intended for elderly or infirm patients who require increased protein intake.

The Acute Effects of Breakfast Drinks with Varying Protein and Energy Contents on Appetite and Free-Living Energy Intake in UK Older Adults

Proposed strategies for preventing protein deficiencies in older patients include increasing protein intake at breakfast. However, protein is highly satiating and the effects of very high protein intakes at breakfast on subsequent appetite and free-living energy intake (EI) in older adults are unclear. This study compared the acute effects of two breakfast drinks varying in protein and energy contents on appetite and free-living EI in healthy older adults using a randomized 2 × 2 crossover design. Participants (n = 48 (20 men, 28 women); mean ± SD age: 69 ± 3 years; BMI: 22.2 ± 2.0 kg·m⁻²; fat-free mass: 45.5 ± 8.0 kg) consumed two drinks for breakfast (high-protein (30.4 ± 5.3 g), low-energy (211.2 ± 37.1 kcal) content (HPLE) and very high-protein (61.8 ± 9.9 g), fed to energy requirements (428.0 ± 68.9 kcal) (VHPER)) one week apart. Appetite perceptions were assessed for 3 h post-drink and free-living EI was measured for the remainder of the day. Appetite was lower in VHPER than HPLE from 30 min onwards (p < 0.01). Free-living energy and protein intake did not differ between conditions (p = 0.814). However, 24 h EI (breakfast drink intake + free-living intake) was greater in VHPER than HPLE (1937 ± 568 kcal vs. 1705 ± 490 kcal; p = 0.001), as was 24 h protein intake (123.0 ± 26.0 g vs. 88.6 ± 20.9 g; p < 0.001). Consuming a very high-protein breakfast drink acutely suppressed appetite more than a low-energy, high-protein drink in older adults, though free-living EI was unaffected. The long-term effects of adopting such a breakfast strategy in older adults at high risk of energy and protein malnutrition warrants exploration.

The Role of Bovine and Non-Bovine Milk in Cardiometabolic Health: Should We Raise the "Baa"?

Although causality is yet to be confirmed, a considerable volume of research has explored the relationships between cow milk consumption, type II diabetes, and cardiovascular disease. Contrastingly, it has not been comprehensively examined whether milk of non-bovine origin can provide cardiometabolic protection. This narrative review outlines the marked differences in macronutrient composition, particularly protein and lipid content, and discusses how whole milk product (and individual milk ingredients) from different species could impact cardiometabolic health. There is some data, although primarily from compositional analyses, animal studies, and acute clinical trials, that non-bovine milk (notably sheep and goat milk) could be a viable substitute to cow milk for the maintenance, or enhancement, of cardiometabolic health. With a high content of medium-chain triglycerides, conjugated linoleic acid, leucine, and essential minerals, sheep milk could assist in the prevention of metabolic-related disorders. Similarly, albeit with a lower content of such functional compounds relative to sheep milk, goat and buffalo milk could be plausible counterparts to cow milk. However, the evidence required to generate nutritional recommendations for ‘non-bovine milk’ is currently lacking. Longer-term randomised controlled trials must assess how the bioactive ingredients of different species’ milks collectively influence biomarkers of, and subsequently incidence of, cardiometabolic health.

Postprandial glycine as a biomarker of satiety: A dose-rising randomised control trial of whey protein in overweight women

This study aimed to identify biomarkers of appetite response, modelled using a dose-rising whey protein preload intervention. Female participants (n = 24) with body mass index (BMI) between 23 and 40 kg/m² consumed preload beverages (0 g protein water control, WC; 12.5 g low-dose protein, LP; or 50.0 g high-dose protein, HP) after an overnight fast, in a randomised cross over design. Repeated venous blood samples were collected to measure plasma biomarkers of appetite response, including glucose, glucoregulatory peptides, gut peptides, and amino acids (AAs). Appetite was assessed using Visual Analogue Scales (VAS) and ad libitum energy intake (EI). Dose-rising protein beverage significantly changed the postprandial trajectory of almost all biomarkers (treatment*time, p < 0.05), but did not suppress postprandial appetite (treatment*time, p > 0.05) or EI (ANOVA, p = 0.799). Circulating glycine had the strongest association with appetite response. Higher area under the curve (AUC_0-240) glycine was associated with lower EI (p = 0.026, trend). Furthermore, circulating glycine was associated with decreased Hunger in all treatment groups, whereas the associations of glucose, alanine and amylin with appetite were dependent on treatment groups. Multivariate models, incorporating multiple biomarkers, improved the estimation of appetite response (marginal R², range: 0.13-0.43). In conclusion, whilst glycine, both alone and within a multivariate model, can estimate appetite response to both water and whey protein beverage consumption, a large proportion of variance in appetite response remains unexplained. Most biomarkers, when assessed in isolation, are poor predictors of appetite response, and likely of utility only in combination with VAS and EI.

Integrated Small RNA Sequencing, Transcriptome and GWAS Data Reveal microRNA Regulation in Response to Milk Protein Traits in Chinese Holstein Cattle

Milk protein is one of the most important economic traits in the dairy industry. Yet, the regulatory network of miRNAs for the synthesis of milk protein in mammary is poorly understood. Samples from 12 Chinese Holstein cows with three high ( ≥ 3.5%) and three low ( ≤ 3.0%) phenotypic values for milk protein percentage in lactation and non-lactation were examined through deep small RNA sequencing. We characterized 388 known and 212 novel miRNAs in the mammary gland. Differentially expressed analysis detected 28 miRNAs in lactation and 52 miRNAs in the non-lactating period with a highly significant correlation with milk protein concentration. Target prediction and correlation analysis identified some key miRNAs and their targets potentially involved in the synthesis of milk protein. We analyzed for enrichments of GWAS signals in miRNAs and their correlated targets. Our results demonstrated that genomic regions harboring DE miRNA genes in lactation were significantly enriched with GWAS signals for milk protein percentage traits and that enrichments within DE miRNA targets were significantly higher than in random gene sets for the majority of milk production traits. This integrated study on the transcriptome and posttranscriptional regulatory profiles between significantly differential phenotypes of milk protein concentration provides new insights into the mechanism of milk protein synthesis, which should reveal the regulatory mechanisms of milk secretion.

Krill Protein Hydrolysate Provides High Absorption Rate for All Essential Amino Acids-A Randomized Control Cross-Over Trial

BACKGROUND

adequate protein intake is essential to humans and, since the global demand for protein-containing foods is increasing, identifying new high-quality protein sources is needed. In this study, we investigated the acute postprandial bioavailability of amino acids (AAs) from a krill protein hydrolysate compared to a soy and a whey protein isolate.

METHODS

the study was a randomized, placebo-controlled crossover trial including ten healthy young males. On four non-consecutive days, volunteers consumed water or one of three protein-matched supplements: whey protein isolate, soy protein isolate or krill protein hydrolysate. Blood samples were collected prior to and until 180 min after consumption. Serum postprandial AA concentrations were determined using ¹H NMR spectroscopy. Hunger and satiety were assessed using visual analogue scales (VAS).

RESULTS

whey and krill resulted in significantly higher AA concentrations compared to soy between 20-60 min and 20-40 min after consumption, respectively. Area under the curve (AUC) analyses revealed that whey resulted in the highest postprandial serum concentrations of essential AAs (EAAs) and branched chain AAs (BCAAs), followed by krill and soy, respectively.

CONCLUSIONS

krill protein hydrolysate increases postprandial serum EAA and BCAA concentrations in a superior manner to soy protein isolate and thus might represent a promising future protein source in human nutrition.

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

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

Review on the Regional Effects of Gastrointestinal Luminal Stimulation on Appetite and Energy Intake: (Pre)clinical Observations

Macronutrients in the gastrointestinal (GI) lumen are able to activate “intestinal brakes”, feedback mechanisms on proximal GI motility and secretion including appetite and energy intake. In this review, we provide a detailed overview of the current evidence with respect to four questions: (1) are regional differences (duodenum, jejunum, ileum) present in the intestinal luminal nutrient modulation of appetite and energy intake? (2) is this “intestinal brake” effect macronutrient specific? (3) is this “intestinal brake” effect maintained during repetitive activation? (4) can the “intestinal brake” effect be activated via non-caloric tastants? Recent evidence indicates that: (1) regional differences exist in the intestinal modulation of appetite and energy intake with a proximal to distal gradient for inhibition of energy intake: ileum and jejunum > duodenum at low but not at high caloric infusion rates. (2) the “intestinal brake” effect on appetite and energy appears not to be macronutrient specific. At equi-caloric amounts, the inhibition on energy intake and appetite is in the same range for fat, protein and carbohydrate. (3) data on repetitive ileal brake activation are scarce because of the need for prolonged intestinal intubation. During repetitive activation of the ileal brake for up to 4 days, no adaptation was observed but overall the inhibitory effect on energy intake was small. (4) the concept of influencing energy intake by intra-intestinal delivery of non-caloric tastants is intriguing. Among tastants, the bitter compounds appear to be more effective in influencing energy intake. Energy intake decreases modestly after post-oral delivery of bitter tastants or a combination of tastants (bitter, sweet and umami). Intestinal brake activation provides an interesting concept for preventive and therapeutic approaches in weight management strategies.

Acute effects of hemp protein consumption on glycemic and satiety control: results of 2 randomized crossover trials

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.

Gastrointestinally Digested Protein from the Insect Alphitobius diaperinus Stimulates a Different Intestinal Secretome than Beef or Almond, Producing a Differential Response in Food Intake in Rats

In this study we compare the interaction of three protein sources—insect, beef, and almond—with the gastrointestinal tract. We measured the enterohormone secretion ex vivo in human and pig intestine treated with in vitro digestions of these foods. Insect and beef were the most effective in inducing the secretion of CCK, while almond was the most effective in inducing PYY in pig duodenum. In the human colon, almond was also the most effective in inducing PYY, and GLP-1 levels were increased by insect and beef. The three digested proteins reduced ghrelin secretion in pig duodenum, while only insect reduced ghrelin secretion in human colon. We also found that food intake in rats increased in groups fed a raw insect pre-load and decreased when fed raw almond. In conclusion, the insect Alphitobius diaperinus modulates duodenal and colonic enterohormone release and increases food intake in rats. These effects differ from beef and almond.

Premeal Consumption of a Protein-Enriched, Dietary Fiber-Fortified Bar Decreases Total Energy Intake in Healthy Individuals

BACKGROUND

A premeal load of protein can increase satiety and reduce energy intake. Dietary fiber also conveys metabolic benefits by modulating energy intake. We made a protein-enriched, dietary fiber-fortified bar (PFB) and aimed to investigate its effects on food intake and gut hormone secretion in healthy individuals.

METHODS

Twenty subjects with normal glucose tolerance were enrolled. On three separate visits, the subjects received, in a randomized order, one of the following: a PFB containing 73 kcal with 10.7 g of protein and 12.7 g of dietary fiber; a usual bar (UB) containing the same calories as the PFB but only 0.9 g of protein and no dietary fiber; or water (control). After 15 minutes, the subjects had ad libitum intake of a test meal. Food consumption, appetite, and plasma gut hormone levels were measured.

RESULTS

Total energy intake, including the bar and the test meal, was significantly reduced with the PFB preload compared to the water (904.4±534.9 kcal vs. 1,075.0±508.0 kcal, P=0.016). With the UB preload, only the intake of the test meal was reduced (P=0.044) but not the total energy intake (P=0.471) than the water. Fullness was also significantly increased after the PFB. In addition, postprandial glucose levels decreased and glucagon-like peptide-1 levels increased with the PFB compared with both the UB and water.

CONCLUSION

In healthy individuals, a premeal supplementation of PFB reduced total energy intake and decreased postprandial glucose excursion. This finding necessitates long-term studies regarding clinical use in obesity.

A randomized cross-over trial to determine the effect of a protein vs. carbohydrate preload on energy balance in ad libitum settings

BACKGROUND

Although high protein diets have been tested in controlled environments for applications to weight management, it is not understood if adding high protein foods to the diet would impact ad libitum energy balance in the absence of other lifestyle changes.

METHODS

This double-blinded randomized crossover trial compared the effects of a protein shake (PS) to a carbohydrate shake (CS), consumed prior to each major meal to equate to 20% of total energy needs over the course of the day, on energy balance over two 5-day treatment periods in healthy adults with BMI 20-30 kg/m2. Tri-axial accelerometers estimated physical activity energy expenditure. Ad libitum energy intake was measured in a laboratory kitchen.

RESULTS

Energy balance was positive during both treatment periods but was not different between periods. There were no interactions between treatment and preload caloric dose or treatment and BMI status on energy balance. Satiety ratings did not differ for any pairwise comparisons between treatment and caloric dose. Controlling for gender and basal metabolic rate, thermic effect of food was greater for PS than CS.

CONCLUSIONS

Preload periods significantly altered the macronutrient composition of the overall diet. This study found limited evidence that carbohydrate or protein preloads have differential effects on energy balance in short-term ad libitum settings.

TRIAL REGISTRATION

This trial was pre-registered on clinicaltrials.gov as NCT02613065 on 11/30/2015.

Plasma Free Amino Acid Responses to Whey Protein and Their Relationships with Gastric Emptying, Blood Glucose- and Appetite-Regulatory Hormones and Energy Intake in Lean Healthy Men

This study determined the effects of increasing loads of whey protein on plasma amino acid (AA) concentrations, and their relationships with gastric emptying, blood glucose- and appetite-regulatory hormones, blood glucose and energy intake. Eighteen healthy lean men participated in a double-blinded study, in which they consumed, on 3 separate occasions, in randomised order, 450-mL drinks containing either 30 g (L) or 70 g (H) of pure whey protein isolate, or control with 0 g of protein (C). Gastric emptying, serum concentrations of AAs, ghrelin, cholecystokinin (CCK), glucagon-like-peptide 1 (GLP-1), insulin, glucagon and blood glucose were measured before and after the drinks over 180 min. Then energy intake was quantified. All AAs were increased, and 7/20 AAs were increased more by H than L. Incremental areas under the curve (iAUC0-180 min) for CCK, GLP-1, insulin and glucagon were correlated positively with iAUCs of 19/20 AAs (p < 0.05). The strongest correlations were with the branched-chain AAs as well as lysine, tyrosine, methionine, tryptophan, and aspartic acid (all R2 > 0.52, p < 0.05). Blood glucose did not correlate with any AA (all p > 0.05). Ghrelin and energy intake correlated inversely, but only weakly, with 15/20 AAs (all R2 < 0.34, p < 0.05). There is a strong relationship between gluco-regulatory hormones with a number of (predominantly essential) AAs. However, the factors mediating the effects of protein on blood glucose and energy intake are likely to be multifactorial.

Beneficial effects of running and milk protein supplements on Sirtuins and risk factors of metabolic disorders in rats with low aerobic capacity

Background

Physical activity and dietary intake of dairy products are associated with improved metabolic health. Dairy products are rich with branched chain amino acids that are essential for energy production. To gain insight into the mechanisms underlying the benefit of the sub-chronic effects of running and intake of milk protein supplements, we studied Low Capacity Runner rats (LCR), a rodent exercise model with risk for metabolic disorders. We especially focused on the role of Sirtuins, energy level dependent proteins that affect many cellular metabolic processes.

Methods

Forty-seven adult LCR female rats sedentary or running voluntarily in wheels were fed normal chow and given supplements of either whey or milk protein drink (PD)-supplemented water, or water only for 21 weeks. Physiological responses were measured in vivo. Blood lipids were determined from serum. Mitochondrial markers and Sirtuins (Sirt1-7) including downstream targets were measured in plantaris muscle by western blotting.

Results

For the first 10 weeks whey-drinking rats ran about 50% less compared to other groups; still, in all runners glucose tolerance improved and triglycerides decreased. Generally, running induced a ∼six-fold increase in running capacity and a ∼8% decrease in % body fat. Together with running, protein supplements increased the relative lean mass of the total body weight by ∼11%. In comparison with sedentary controls, running and whey increased HDL (21%) and whey, with or without running, lowered LDL (−34%). Running increased mitochondrial biogenesis and Sirtuins 3 and 4. When combined with exercise, both whey and milk protein drink induced about a 4-fold increase in Sirt3, compared to runners drinking water only, and about a 2-fold increase compared to the respective sedentary group. Protein supplements, with or without running, enhanced the phosphorylation level of the acetyl-coA-carboxylase, suggesting increased fat oxidation. Both supplemented diets increased Sirt5 and Sirt7 without an additional effect from exercise. Running diminished and PD supplement increased Sirt6.

Conclusion

We demonstrate in rats new sub-chronic effects of milk proteins on metabolism that involve Sirtuins and their downstream targets in skeletal muscle. The results show that running and milk proteins act on reducing the risk factors of metabolic disorders and suggest that the underlying mechanisms may involve Sirtuins. Notably, we found that milk protein supplements have some favorable effects on metabolism even without running.

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Interactive effects of running and/or milk protein supplements were studied.

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Milk protein drink enhanced and whey diminished the amount of voluntary running.

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Despite less running whey-supplementation improved metabolic health.

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Almost all Sirtuins in muscle adapted to milk protein and running interventions.

Gastrointestinal Sensing of Meal-Related Signals in Humans, and Dysregulations in Eating-Related Disorders

The upper gastrointestinal (GI) tract plays a critical role in sensing the arrival of a meal, including its volume as well as nutrient and non-nutrient contents. The presence of the meal in the stomach generates a mechanical distension signal, and, as gastric emptying progresses, nutrients increasingly interact with receptors on enteroendocrine cells, triggering the release of gut hormones, with lipid and protein being particularly potent. Collectively, these signals are transmitted to the brain to regulate appetite and energy intake, or in a feedback loop relayed back to the upper GI tract to further adjust GI functions, including gastric emptying. The research in this area to date has provided important insights into how sensing of intraluminal meal-related stimuli acutely regulates appetite and energy intake in humans. However, disturbances in the detection of these stimuli have been described in a number of eating-related disorders. This paper will review the GI sensing of meal-related stimuli and the relationship with appetite and energy intake, and examine changes in GI responses to luminal stimuli in obesity, functional dyspepsia and anorexia of ageing, as examples of eating-related disorders. A much better understanding of the mechanisms underlying these dysregulations is still required to assist in the development of effective management and treatment strategies in the future.

The Effect of Exercise and Protein Source on Food Intake Regulation and Characteristics of Metabolic Syndrome in Obese Female Wistar Rats

Results:

FI and plasma ghrelin (2.7 times) were higher in exercise groups compared with non-exercise groups. BW was lower (6.7%) in groups fed a whey protein diet compared with those fed a soy protein diet. Abdominal fat (% BW) was lower (22.8%) in WPE compared with other groups. Diastolic blood pressure (11.1%) and pulse (6%) were lower in groups fed a soy protein diet compared with groups fed a whey protein diet.

Conclusion:

While exercise affects food intake, source of protein determines BW and BC. Whey protein showed more favorable effect on BW and body composition.

Intraduodenal Administration of L-Valine Has No Effect on Antropyloroduodenal Pressures, Plasma Cholecystokinin Concentrations or Energy Intake in Healthy, Lean Men

Whey protein is rich in the branched-chain amino acids, L-leucine, L-isoleucine and L-valine. Thus, branched-chain amino acids may, at least in part, mediate the effects of whey to reduce energy intake and/or blood glucose. Notably, 10 g of either L-leucine or L-isoleucine, administered intragastrically before a mixed-nutrient drink, lowered postprandial blood glucose, and intraduodenal infusion of L-leucine (at a rate of 0.45 kcal/min, total: 9.9 g) lowered fasting blood glucose and reduced energy intake from a subsequent meal. Whether L-valine affects energy intake, and the gastrointestinal functions involved in the regulation of energy intake, as well as blood glucose, in humans, is currently unknown. We investigated the effects of intraduodenally administered L-valine on antropyloroduodenal pressures, plasma cholecystokinin, blood glucose and energy intake. Twelve healthy lean men (age: 29 ± 2 years, BMI: 22.5 ± 0.7 kg/m²) were studied on 3 separate occasions in randomised, double-blind order. Antropyloroduodenal pressures, plasma cholecystokinin, blood glucose, appetite perceptions and gastrointestinal symptoms were measured during 90-min intraduodenal infusions of L-valine at 0.15 kcal/min (total: 3.3 g) or 0.45 kcal/min (total: 9.9 g), or 0.9% saline (control). Energy intake from a buffet-meal immediately after the infusions was quantified. L-valine did not affect antral, pyloric (mean number; control: 14 ± 5; L-Val-0.15: 21 ± 9; L-Val-0.45: 11 ± 4), or duodenal pressures, plasma cholecystokinin (mean concentration, pmol/L; control: 3.1 ± 0.3; L-Val-0.15: 3.2 ± 0.3; L-Val-0.45: 3.0 ± 0.3), blood glucose, appetite perceptions, symptoms or energy intake (kcal; control: 1040 ± 73; L-Val-0.15: 1040 ± 81; L-Val-0.45: 1056 ± 100), at either load (p > 0.05 for all). In conclusion, intraduodenal infusion of L-valine, at loads that are moderately (3.3 g) or substantially (9.9 g) above World Health Organization valine requirement recommendations, does not appear to have energy intake- or blood glucose-lowering effects.

Influence of rice, pea and oat proteins in attenuating glycemic response of sugar-sweetened beverages

PURPOSE

Liquids have higher ingestion and gastric-emptying rates, resulting in rapid glycemic response. They are also less satiating than solid foods. This study examined if the addition of plant proteins alter postprandial glucose, insulin, triglycerides, glucose-dependent insulinotropic peptide (GIP), glycogen-like peptide-1 (GLP-1) and appetitive responses to a sugar-sweetened beverage.

METHODS

This was a randomized, crossover acute feeding study consisting of four treatments: chocolate beverage alone (50 g carbohydrate), or added with 24 g oat, pea or rice proteins. Twenty Chinese males (mean ± SD age 26 ± 5 years; body mass index 21.5 ± 1.7 kg/m2) ingested the test drink after an overnight fast. Venous blood samples and subjective appetite ratings were collected before test beverage and at fixed intervals for 180 min. Blood biochemical data and appetite ratings were compared using repeated-measures ANOVA.

RESULTS

Significant interaction effects were found in postprandial glucose excursions (time × protein effects, p = 0.003). Glucose iAUC was lower in pea and rice proteins, although not significantly (p > 0.385). Insulin iAUC was significantly higher in the oat (p = 0.035) and pea (p = 0.036) protein beverages. GIP and GLP-1 release in a sub-sample (n = 10) followed a comparable order as insulin release (p = 0.397 and 0.454, respectively). Significant interaction effects were found in fullness ratings (p = 0.024), and a trend of greater suppression of hunger and desire-to-eat was also documented (p = 0.088 and 0.080, respectively).

CONCLUSIONS

Plant proteins altered the glycemic and appetitive responses of Asian males to a sugar-sweetened beverage. Food-based interventions are useful in promoting glycemic control. This trial was registered with ClinicalTrials.gov as NCT02933424.

The effects of whey and soy liquid breakfast on appetite response, energy metabolism, and subsequent energy intake

OBJECTIVES

The aim of this study was to examine the effects of animal-based protein (whey; WP) compared with plant-based protein (soy; SP) and carbohydrate (CHO) liquid breakfast on appetite, energy metabolism, and subsequent energy intake.

METHODS

Seventeen healthy individuals consumed three isocaloric breakfast smoothies with whey, soy, or carbohydrate (no protein) in a double-blind, randomized crossover design. Participants completed an 11-point rating scale of appetite profile (before, 0, 60, 120, and 180 min). Indirect calorimetry was used to determine the thermic effect of a meal (TEM; at 45-60, 105-120, and 165-180 min). An ad libitum lunch was offered at 180 min after breakfast and energy intake was assessed.

RESULTS

There was a significant difference in hunger (P = 0.033), fullness (P = 0.002), satiety (P = 0.001), desire to eat (P = 0.024), and prospective food consumption (P = 0.021) between the three breakfast meals. Fullness and SP compared with CHO. A higher (P < 0.001) TEM and lower (P < 0.05) respiratory exchange ratio (RER) was observed after WP and SP compared with CHO. In addition, a higher (P = 0.022) energy intake at lunch was observed after CHO (769 ± 259 kcal) compared with WP (654 ± 252 kcal) and SP (664 ± 296 kcal), with no difference (P = 0.966) between WP and SP. Consuming SP at breakfast exerts comparable effects to WP on appetite profile, energy metabolism, and subsequent energy intake, suggesting that SP is a reasonable alternative to WP as a protein supplement source to aid in body weight control.

Comparison of Low Glycaemic Index and High Glycaemic Index Potatoes in Relation to Satiety: A Single-Blinded, Randomised Crossover Study in Humans

High glycaemic index (GI) foods have been proposed to reduce satiety and thus promote overweight and obesity. Generally, potatoes have a high GI, but they also provide many beneficial nutrients and they are a highly important food source globally. In this study, we investigated how a low GI potato affected subjective satiety as compared to a high GI potato. Twenty healthy men (aged 18–40 years; body mass index (BMI) 18–27 kg/m²) participated in this single-blinded, controlled, randomised crossover trial. On each of the two trial days, the subjects were given a 500-gram portion of either a low or high GI potato variety (Carisma^® low GI and Arizona high GI). Subjective appetite sensations were measured at baseline and at +15 min, +45 min, +75 min, +105 min, and +135 min after consumption of the test meal until an ad libitum meal was served at +150 min. No significant differences in the primary endpoint, satiety, were found between the two potato varieties (all p > 0.05). Furthermore, no significant differences were found in the secondary endpoints; hunger, fullness, and prospective food consumption, or ad libitum energy intake (all p > 0.05). In conclusion, the results of this study do not indicate that the GI of potatoes is important for satiety in normal-weight men.

Wheat gluten hydrolysate potently stimulates peptide-YY secretion and suppresses food intake in rats

The study was aimed to compare the satiating effect of various protein hydrolysates in rats and examine the underlying mechanism associated with the satiety hormones. Food intake and portal satiety hormone levels were measured in rats. Enteroendocrine cell-lines were employed to study the direct effect of protein hydrolysates on gut hormone secretions. The results showed that oral preload of wheat gluten hydrolysate (WGH) suppressed food intake greater and longer than other hydrolysates. The portal peptide-YY levels in WGH-treated rats at 2 h and 3 h were higher than those in control- and lactalbumin hydrolysate (LAH)-treated rats. In a distal enteroendocrine cell model, WGH more potently stimulated glucagon-like peptide-1 secretion than LAH, and the effect was largely enhanced by pepsin/pancreatin digestion of WGH. These results suggest WGH is potent in activating enteroendocrine cells to release satiety hormones leading to the prolonged suppression of food intake.

Consuming Lower-Protein Nutrition Bars with Added Leucine Elicits Postprandial Changes in Appetite Sensations in Healthy Women

BACKGROUND

Higher-protein meals (>25 g protein/meal) have been associated with enhanced satiety but the role of amino acids is unclear. Leucine has been proposed to stimulate satiety in rodents but has not been assessed in humans.

OBJECTIVE

We assessed the acute effects of lower-protein nutrition bars, enhanced with a leucine peptide (LP), on postprandial appetite sensations in combination with plasma leucine and peptide YY (PYY) in healthy women.

METHODS

Utilizing a double-blind randomized crossover design, 40 healthy women [28 ± 7.5 y; body mass index (BMI, in kg/m2): 23.5 ± 2.4] consumed the following isocaloric (180 kcal) pre-loads on 3 separate visits: control bar [9 g protein with 0 g added LP (0-g LP)] or treatment bars [11 g protein with 2 g added LP (2-g LP) or 13 g protein with 3 g added LP (3-g LP)]. Pre- and postprandial hunger, desire to eat, prospective food consumption (PFC), fullness, and plasma leucine were assessed every 30 min for 240 min. Plasma PYY was assessed hourly for 240 min (n = 24).

RESULTS

Main effects of time (P < 0.0001) and treatment (P < 0.03) were detected for postprandial hunger, desire to eat, PFC, and fullness. Post hoc analyses revealed that the 2-g and 3-g LP bars elicited greater increases in fullness and greater decreases in PFC compared with 0-g LP (all, P < 0.05) with no differences between the 2-g and 3-g LP bars. The 2-g bar elicited greater decreases in hunger and desire to eat compared with the 0-g LP bar (both, P ≤ 0.01), whereas 3-g LP did not. Appetite incremental areas under the curves (iAUCs) and PYY outcomes were not different between bars. A treatment × time interaction was detected for plasma leucine with increases occurring in a leucine-dose-dependent manner (P < 0.0001).

CONCLUSION

Despite the dose-dependent increases in plasma leucine following the consumption of lower-protein bars enhanced with LP, only the 2-g LP bar elicited consistent postprandial changes in select appetite sensations compared with the 0-g LP bar. This study was registered on clinicaltrials.gov as NCT02091570.

Comparable effects of breakfast meals varying in protein source on appetite and subsequent energy intake in healthy males

PURPOSE

The satiating effect of animal vs plant proteins remains unknown. The present study examined the effects of breakfasts containing animal proteins [milk (AP)], a blend of plant proteins [oat, pea and potato (VP)] or 50:50 mixture of the two (MP) compared with a carbohydrate-rich meal (CHO) on appetite, energy intake (EI) and metabolic measures.

METHODS

A total of 28 males [mean age 27.4 (±SD 4.2) years, BMI 23.4 (±2.1) kg/m2] consumed three isoenergetic (1674 kJ) rice puddings matched for energy density and macronutrient content as breakfast (25% E from protein) in a single-blind, randomised, cross over design. Appetite ratings and blood samples were collected and assessed at baseline and every 30 and 60 min, respectively, until an ad libitum test meal was served 3.5 h later. Free-living appetite was recorded hourly and EI in weighed food records for the remainder of the day.

RESULTS

No differences in subjective appetite ratings were observed after consumption of the AP, VP and MP. Furthermore, there were no differences between the AP, VP, MP and CHO breakfasts in ad libitum EI and self-reported EI during the remainder of the day. Although insulin metabolism was not affected, CHO induced a higher glucose response (P = 0.001) and total amino acids concentration was in the order of AP = MP > VP > CHO breakfast (P = 0.001).

CONCLUSION

Manipulating the protein source of foods consumed as breakfast, elicited comparable effects on appetite and EI at both laboratory and free-living environment in healthy men.

Effect of Commercially Available Sugar-Sweetened Beverages on Subjective Appetite and Short-Term Food Intake in Girls

Background: The effect of sugar-sweetened beverages (SSBs) on satiety and short-term food intake (FI) regulation in girls has received little attention. The objective of the present study was to compare the effect of pre-meal consumption of commercially available SSBs on subjective appetite and short-term FI in 9–14-year-old girls. The methods we used include using a randomized crossover design in which 28 girls consumed isovolumetric amounts (350 mL) of a fruit drink (154 kcal), cola (158 kcal), 1% chocolate milk (224 kcal), or water (control; 0 kcal) on four separate mornings. Subjective appetite and thirst were measured at regular intervals via visual analogue scales (VAS) and FI was assessed at 60 min post-beverage consumption. The results show that subjective appetite and thirst decreased after all beverages, but did not differ among beverages. Short-term FI was suppressed following consumption of chocolate milk (15%; p < 0.001) and cola (11%; p = 0.02) compared to the water control. However, cumulative energy intake (beverage (kcal) + test meal (kcal)) was not affected by beverage type. In conclusion, chocolate milk and cola, but not fruit drink, suppressed FI in girls while cumulative FI did not differ among treatments.

Protein from Meat or Vegetable Sources in Meals Matched for Fiber Content has Similar Effects on Subjective Appetite Sensations and Energy Intake-A Randomized Acute Cross-Over Meal Test Study

Higher-protein meals decrease hunger and increase satiety compared to lower-protein meals. However, no consensus exists about the different effects of animal and vegetable proteins on appetite. We investigated how a meal based on vegetable protein (fava beans/split peas) affected ad libitum energy intake and appetite sensations, compared to macronutrient-balanced, iso-caloric meals based on animal protein (veal/pork or eggs). Thirty-five healthy men were enrolled in this acute cross-over study. On each test day, participants were presented with one of four test meals (~3550 kilojoules (kJ) 19% of energy from protein), based on fava beans/split peas (28.5 g fiber), pork/veal or eggs supplemented with pea fiber to control for fiber content (28.5 g fiber), or eggs without supplementation of fiber (6.0 g fiber). Subjective appetite sensations were recorded at baseline and every half hour until the ad libitum meal three hours later. There were no differences in ad libitum energy intake across test meals (p > 0.05). Further, no differences were found across meals for hunger, satiety, fullness, prospective food consumption, or composite appetite score (all p > 0.05). Iso-caloric, macronutrient-balanced, fiber-matched meals based on vegetable protein (fava beans/split peas) or animal protein (veal/pork or eggs) had similar effects on ad libitum energy intake and appetite sensations.

Yogurt and Cardiometabolic Diseases: A Critical Review of Potential Mechanisms

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

Comparative effects of intraduodenal amino acid infusions on food intake and gut hormone release in healthy males

In contrast to the many studies of the effects of individual amino acids (AAs) on eating, no studies have compared the effects of different AAs on eating and underlying preabsorptive gastrointestinal mechanisms. To compare the effects of intraduodenal infusions of l-tryptophan (TRP), l-leucine (LEU), l-phenylalanine (PHE) and l-glutamine (GLN) on appetite, gastrointestinal hormone responses (including ghrelin, cholecystokinin (CCK), peptide YY (PYY) and glucagon-like peptide-1 [GLP-1]), glycemia (glucagon, insulin and glucose) and test meal size in healthy males, we retrospectively analyzed data from four published independent, randomized, double-blind, placebo-controlled studies of 90-min intraduodenal infusions of the individual AAs. The designs of the studies were identical, except the dose of TRP (0.15 kcal/min) was lower than that of the other AAs (0.45 kcal/min) because higher doses of this AA were not well tolerated. TRP and LEU decreased intake more than PHE (reductions relative to control, ~219 ± 68, ~170 ± 48 and ~12 ± 57 kcal, respectively), and TRP decreased intake more than GLN (~31 ± 82 kcal). These effects of TRP and LEU versus GLN, but not versus PHE, were paralleled by greater decreases in plasma ghrelin, and increases in CCK, concentrations. TRP increased PYY more than GLN or LEU, but not PHE. LEU increased PYY less than PHE. No significant differences were detected for GLP-1. PHE increased glucagon more than TRP or LEU, and increased insulin more than TRP. Under our experimental conditions, intraduodenal TRP and LEU were more satiating than PHE and GLN. The greater satiating efficacy of LEU versus PHE was significantly dissociated from the effects of these AAs on PYY, while the greater satiating potency of TRP versus PHE was significantly dissociated from the effects of these AAs on insulin and glucagon. In contrast, ghrelin and CCK, and potentially other mechanisms, including central sensing of individual AAs, appear to be stronger candidate mechanisms for the relative satiating effects obtained.

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.