Effect of metabolic state on implicit and explicit responses to food in young healthy females.

Recent neuroscience research has delineated key psychological components of reward: wanting, liking and learning. Each component is further divided into explicit and implicit processes. While explicit processes are consciously experienced, implicit processes are not always directly accessible to conscious inspection. In the present study, we investigated the effect of metabolic state on implicit and explicit responses and their relationship in food context, especially when foods and visually matched non-food items are contrasted, and when foods in a sole food context but differing in energy content (high-energy - low-energy) or taste (sweet - savoury) were contrasted. Sixty healthy non-obese females participated in the study in fasted and fed states. Three Implicit Association Tests were used to assess implicit associations. Explicit liking and wanting ratings were assessed by visual analogue scales. In the implicit food-non-food context, food was preferred over non-food items both in fasted and fed states, though the strength of implicit associations declined significantly from fasted to fed state. However, the direction or strength of implicit associations was not significantly different between the metabolic states when comparing concepts within food context only, differing in energy content or taste. Instead, explicit responses reflected the change in the metabolic state in a manner consistent with alliesthesia and sensory-specific satiety. The results of the present study suggest that implicit associations are relatively resistant to acute change in the metabolic condition compared to explicit ratings, which shift more readily according to the fasted-fed continuum. The shift in the prevailing metabolic state was, however, reflected in the strength of implicit responses towards food in relation to non-food items, yet in the sole food contexts implicit associations were comparable between the fasted and fed states.

Impact of Diet Composition on Blood Glucose Regulation.

Nutritional management of blood glucose levels is a strategic target in the prevention and management of type 2 diabetes mellitus (T2DM). To implement such an approach, it is essential to understand the effect of food on glycemic regulation and on the underlying metabolic derangements. This comprehensive review summarizes the results from human dietary interventions exploring the impact of dietary components on blood glucose levels. Included are the major macronutrients; carbohydrate, protein and fat, micronutrient vitamins and minerals, nonnutrient phytochemicals and additional foods including low-calorie sweeteners, vinegar, and alcohol. Based on the evidence presented in this review, it is clear that dietary components have significant and clinically relevant effects on blood glucose modulation. An integrated approach that includes reducing excess body weight, increased physical activity along with a dietary regime to regulate blood glucose levels will not only be advantages in T2DM management, but will benefit the health of the population and limit the increasing worldwide incidence of T2DM.

High perceived stress is associated with unfavorable eating behavior in overweight and obese Finns of working age.

Stress-related eating may be a potential factor in the obesity epidemic. Rather little is known about how stress associates with eating behavior and food intake in overweight individuals in a free-living situation. Thus, the present study aims to investigate this question in psychologically distressed overweight and obese working-aged Finns. The study is a cross-sectional baseline analysis of a randomized controlled trial. Of the 339 study participants, those with all the needed data available (n = 297, 84% females) were included. The mean age was 48.9 y (SD = 7.6) and mean body mass index 31.3 kg/m(2) (SD = 3.0). Perceived stress and eating behavior were assessed by self-reported questionnaires Perceived Stress Scale (PSS), Intuitive Eating Scale, the Three-Factor Eating Questionnaire, Health and Taste Attitude Scales and ecSatter Inventory. Diet and alcohol consumption were assessed by 48-h dietary recall, Index of Diet Quality, and AUDIT-C. Individuals reporting most perceived stress (i.e. in the highest PSS tertile) had less intuitive eating, more uncontrolled eating, and more emotional eating compared to those reporting less perceived stress (p < 0.05). Moreover, individuals in the highest PSS tertile reported less cognitive restraint and less eating competence than those in the lowest tertile (p < 0.05). Intake of whole grain products was the lowest among those in the highest PSS tertile (p < 0.05). Otherwise the quality of diet and alcohol consumption did not differ among the PSS tertiles. In conclusion, high perceived stress was associated with the features of eating behavior that could in turn contribute to difficulties in weight management. Stress-related way of eating could thus form a potential risk factor for obesity. More research is needed to develop efficient methods for clinicians to assist in handling stress-related eating in the treatment of obese people.

Cross-linking of sodium caseinate-structured emulsion with transglutaminase alters postprandial metabolic and appetite responses in healthy young individuals.

The physico-chemical and interfacial properties of fat emulsions influence lipid digestion and may affect postprandial responses. The aim of the present study was to determine the effects of the modification of the interfacial layer of a fat emulsion by cross-linking on postprandial metabolic and appetite responses. A total of fifteen healthy individuals (26.5 (sem 6.9) years and BMI 21.9 (sem 2.0) kg/m2) participated in a cross-over design experiment in which they consumed two isoenergetic (1924 kJ (460 kcal)) and isovolumic (250 g) emulsions stabilised with either sodium caseinate (Cas) or transglutaminase-cross-linked sodium caseinate (Cas-TG) in a randomised order. Blood samples were collected from the individuals at baseline and for 6 h postprandially for the determination of serum TAG and plasma NEFA, cholecystokinin (CCK), glucagon-like peptide 1 (GLP-1), glucose and insulin responses. Appetite was assessed using visual analogue scales. Postprandial TAG and NEFA responses and gastric emptying (GE) rates were comparable between the emulsions. CCK increased more after the ingestion of Cas-TG than after the ingestion of Cas (P< 0.05), while GLP-1 responses did not differ between the two test emulsions. Glucose and insulin profiles were lower after consuming Cas-TG than after consuming Cas (P< 0.05). The overall insulin, glucose and CCK responses, expressed as areas above/under the curve, did not differ significantly between the Cas and Cas-TG meal conditions. Satiety ratings were reduced and hunger, desire to eat and thirst ratings increased more after the ingestion of Cas-TG than after the ingestion of Cas (P< 0.05). The present results suggest that even a subtle structural modification of the interfacial layer of a fat emulsion can alter the early postprandial profiles of glucose, insulin, CCK, appetite and satiety through decreased protein digestion without affecting significantly on GE or overall lipid digestion.

Crosslinking with transglutaminase does not change metabolic effects of sodium caseinate in model beverage in healthy young individuals.

BACKGROUND: Postprandial metabolic and appetitive responses of proteins are dependent on protein source and processing technique prior to ingestion. Studies on the postprandial effects of enzymatic crosslinking of milk proteins are sparse. Our aim was to study the effect of transglutaminase (TG)-induced crosslinking of sodium caseinate on postprandial metabolic and appetite responses. Whey protein was included as reference protein. METHODS: Thirteen healthy individuals (23.3 ± 1.1 y, BMI 21.7 ± 0.4 kg/m2) participated in a single-blind crossover design experiment in which the subjects consumed three different isovolumic (500 g) pourable beverages containing either sodium caseinate (Cas, 29 g), TG-treated sodium caseinate (Cas-TG, 29 g) or whey protein (Wh, 30 g) in a randomized order. Blood samples were collected at baseline and for 4 h postprandially for the determination of plasma glucose, insulin and amino acid (AA) concentrations. Gastric emptying (GE) was measured using the 13 C-breath test method. Appetite was assessed using visual analogue scales. RESULTS: All examined postprandial responses were comparable with Cas and Cas-TG. The protein type used in the beverages was reflected as differences in plasma AA concentrations between Wh and Cas, but there were no differences in plasma glucose or insulin responses. A tendency for faster GE rate after Wh was detected. Appetite ratings or subsequent energy intake did not differ among the protein beverages. CONCLUSIONS: Our results indicate that the metabolic responses of enzymatically crosslinked and native sodium caseinate in a liquid matrix are comparable, suggesting similar digestion and absorption rates and first pass metabolism despite the structural modification of Cas-TG.

Structure modification of a milk protein-based model food affects postprandial intestinal peptide release and fullness in healthy young men.

Physico-chemical and textural properties of foods in addition to their chemical composition modify postprandial metabolism and signals from the gastrointestinal tract. Enzymatic cross-linking of protein is a tool to modify food texture and structure without changing nutritional composition. We investigated the effects of structure modification of a milk protein-based model food and the type of milk protein used on postprandial hormonal, metabolic and appetitive responses. Healthy males (n 8) consumed an isoenergetic and isovolumic test product containing either whey protein (Wh, low-viscous liquid), casein (Cas, high-viscous liquid) or Cas protein cross-linked with transglutaminase (Cas-TG, rigid gel) in a randomised order. Blood samples were drawn for plasma glucose, insulin, cholecystokinin (CCK), glucagon-like peptide 1 and peptide YY analysis for 4 h. Appetite was assessed at concomitant time points. Cas and Wh were more potent in lowering postprandial glucose than Cas-TG during the first hour. Insulin concentrations peaked at 30 min, but the peaks were more pronounced for Cas and Wh than for Cas-TG. The increase in CCK was similar for Cas and Wh in the first 15 min, whereas for Cas-TG, the CCK release was significantly lower, but more sustained. The feeling of fullness was stronger after the consumption of Cas-TG than after the consumption of Cas and Wh. The present results suggest that food structure is more effective in modulating the postprandial responses than the type of dairy protein used. Modification of protein-based food structure could thus offer a possible tool for lowering postprandial glucose and insulin concentrations and enhancing postprandial fullness.

A psyllium fiber-enriched meal strongly attenuates postprandial gastrointestinal peptide release in healthy young adults.

Dietary fiber (DF) and protein are essential constituents of a healthy diet and are well known for their high satiety impact. However, little is known about their influence on postprandial gastrointestinal (GI) peptide release. Our aim in this single-blind, randomized, cross-over study was to investigate the effects of DF and/or protein enrichments on satiety-related metabolic and hormonal responses. Sixteen healthy, nonobese volunteers participated in the study and ingested 1 of 5 isoenergetic test meals in a randomized order on separate days. The test meals were as follows: 1) low in protein (2.8 g) and fiber (7.6 g); 2) low in protein (2.6 g) and high in soluble fiber (psyllium, 23.0 g); 3) high in protein (soy, 19.7 g) and low in fiber (6.2 g); 4) high in protein (18.4 g) and fiber (23.0 g); and 5) white wheat bread. Serum insulin and plasma glucose, ghrelin, glucagon-like peptide 1 (GLP-1), and peptide YY (PYY) concentrations were determined for 2 h following the meals. In addition, hunger and satiety ratings were collected. Postprandial glucose, insulin, ghrelin, GLP-1, and PYY responses all differed among the meals (P

Viscosity of oat bran-enriched beverages influences gastrointestinal hormonal responses in healthy humans.

Viscous fibers, including beta-glucan in oat bran, favorably affect satiety as well as postprandial carbohydrate and lipid metabolism. However, effects of fiber viscosity on modulation of satiety-related gut hormone responses are largely unknown. We examined the effects of modified oat bran, with or without its natural viscosity, on sensations of appetite and satiety-related gastrointestinal (GI) hormone responses to establish the relevance of viscosity of beta-glucan in oat bran. Twenty healthy, normal-weight participants (16 female, 4 male, aged 22.6 +/- 0.7 y) ingested 2 isocaloric (1250 kJ) 300-mL oat bran beverages with low or high viscosity (carbohydrates, 57.9 g; protein, 7.8 g; fat, 3.3 g; fiber, 10.2 g) after a 12-h fast in randomized order. Viscosity of the low-viscosity oat bran beverage was reduced by beta-glucanase treatment. Blood samples were drawn before and 15, 30, 45, 60, 90, 120, and 180 min after beverage consumption. The oat bran beverage with low viscosity induced a greater postprandial increase in satiety (P = 0.048) and plasma glucose (P < 0.001), insulin (P = 0.008), cholecystokinin (P = 0.035), glucagon-like peptide 1 (P = 0.037), and peptide YY (P = 0.051) and a greater decrease in postprandial ghrelin (P = 0.009) than the beverage with high-viscosity oat bran. Gastric emptying as measured by paracetamol absorption was also faster (P = 0.034) after low-viscosity oat bran beverage consumption. In conclusion, viscosity differences in oat beta-glucan in a liquid meal with identical chemical composition strongly influenced not only glucose and insulin responses, but also short-term gut hormone responses, implying the importance of food structure in the modulation of postprandial satiety-related physiology.

[Regulation of food intake by gastrointestinal peptides]. / Ruoansulatuskanavan peptidit kylläisyyden säätelyssä--miten ravinto vaikuttaa?

Short-term regulation of food intake controls what, when and how much we eat during a single day or a meal, and is regulated by mechanical stimulation and release of peptides in the gastrointestinal (GI) tract. Both composition and structure of food affect peptide release. Many of these peptides inhibit also GI motility. Macronutrients stimulate GI peptides in different ways. Of special interest are the peptides ghrelin, cholecystokinin, glucagon-like peptide 1 and peptide YY. The amount of existing literature is, however, limited, and the results somewhat contradictory, which makes it challenging to make conclusions about the exact role of different macronutrients.

Metabolic state as a modulator of neural event-related potentials for food stimuli in an implicit association test.

The Implicit Association Test (IAT) has become a ubiquitous measure of implicit associations or preferences in several fields of research, including research related to food choices. The neural dynamics of the IAT have been explored in several contexts, but in a food-related IAT with stimuli of natural motivational value they are yet to be studied. Additionally, the effect of metabolic state on them is poorly known. The present study examined the event-related potentials (ERP) in healthy non-obese females (n = 32) while they performed a food-related IAT in two sessions, in a fasted state and after a meal. The results showed differences in the ERP components N400, P3 and LPP by congruence categories. Additionally, the individual N400 and LPP deflections correlated strongly with individual IAT effects. ERP deflections were weaker in the fasted state than after the meal despite greater implicit hedonic motivation towards food in the fasted state. In conclusion, the results suggest that ERPs reflect the IAT effect. The N400, P3 and LPP components were evoked in a food-related IAT in a similar way observed in IAT tests in other contexts, reflecting a difference in meaning and motivation between congruence categories. The strong correlations of individual IAT effect with individual N400 and LPP deflections further suggests that the food-related IAT effect strength reflects the size of implicit food bias seen in neural deflections. Moreover, fasting increased implicit hedonic motivation towards food, but likely reduced cognitive resources at the same time. This could have made it harder to determine the value of novel, task-relevant stimuli, whereas it became easier postprandially and with practice.