Subjects consumed the test meals at and then fasted until the standardized breakfast. The subjects arrived at the experimental department at the next morning.
Fasting blood tests were collected and satiety and breath H 2 registered before consuming the breakfast. The subjects were instructed to maintain low physical activity throughout the following 3 h of blood sampling. Finger-prick capillary blood samples were withdrawn repeatedly for determination of blood glucose concentrations HemoCue B-glucose, HemoCue. A time schedule for determination of the physiological variables is presented in Table 3.
The procedure for the determination of serum IL-6 concentration was modified in the respect that no dilution of serum was performed prior to the analysis. Serum triacylglycerols were analyzed with a Serum Triglyceride Determination kit Sigma. The true triacylglycerol concentrations were determined by subtracting circulating glycerol from total glycerol that also include the glycerol in triacylglycerol. Plasma adiponectin concentrations were measured at breakfast following the OB bread and the WWB, respectively, and the concentrations were determined with a solid phase 2-site enzyme immunoassay kit Mercodia Adiponectin ELISA, Mercodia.
The positive incremental area under the curve IAUC was used for expressing the results of glucose, insulin, and paracetamol responses. GraphPad Prism version 4. Spearman rank correlation was used to study relations between some of the test variables.
We calculated a correlation for each subject and from these values we obtained the mean value of Spearman correlation coefficient. To determined the P -value, a permutation test was performed using MATLAB with the null hypothesis that no correlations existed the alternative hypothesis was that the data were correlated.
Pearson correlation was used to assess relations involving serum IL-6 and plasma adiponectin, respectively. The different cereal evening meals did not result in significant differences in fasting values of blood glucose, serum insulin, or plasma glucagon by the subsequent morning.
The evening meals with OB bread and CutOB bread resulted in similar mean glucose increments 0—60 min after the start of the standardized breakfast Fig. Thereafter, the glucose increment declined more rapidly following the evening meal with CutOB bread compared with OB bread. The evening meals differed in GI and contents of indigestible carbohydrates.
All meals were based on 50 g available starch. B-glucose, S-insulin, P-glucagon, S-FFA, and breath H 2 of subjects after they consumed the standardized breakfast following cereal-based test evening meals 1. B; blood, S; serum, P; plasma. Glucose and insulin peak values are based on the mean of the individual peaks. Plasma adiponectin concentrations were measured at breakfast following the OB bread and the WWB evening meals.
The fasting concentrations of plasma adiponectin were higher following the evening meal containing OB bread At 45 min after the standardized breakfast, plasma adiponectin did not differ between WWB In contrast, at breakfast, the serum triacylglycerols did not differ depending on the test meal consumed the previous evening. The fasting plasma GLP-1 Fig. Expressed as 0— min AUC, the plasma GIP response did not differ after the standardized breakfast depending on test evening meals.
However, the differences in plasma GIP concentrations after the breakfast tended to increase toward the late postprandial phase. Expressing the results as mean values 0— min , the plasma IL-6 concentration after the standardized breakfast was lower following the OB bread evening meal There were no differences in plasma IL-8 concentrations following the standardized breakfast irrespective of the preceding evening meals.
In addition, the colonic fermentation was higher in the late postprandial phase post the breakfast at min after the OB bread evening meal Concentrations of subjects' breath H 2 excretion indicator of colonic fermentation A , serum paracetamol measure of the GER B , and satiety scores C after the standardized breakfast following different cereal-based evening meals.
After the evening meal with WWB, the serum paracetamol concentration after the standardized breakfast reached a peak value at 60 min, whereas the rest of the evening test meals resulted in a continuous increase of this marker throughout the test period 0—90 min. An evening meal of barley kernel bread OB bread significantly improved glucose tolerance at a following standardized breakfast in healthy subjects. This is an important finding when aiming at exploiting the benefits of cereal products in new and palatable low-GI foods with optimal benefits to blood glucose regulation.
In previous studies, no significant effects on overnight glucose tolerance were observed when adding DF with no added RS from wheat, barley, or oats to a high- or low-GI evening meal in quantities similar to that in barley kernels 13 , The results from this study therefore indicate that low-GI features per se do not seem to be necessary for overnight benefits to glucose tolerance. This indicates that the elevated level of indigestible carbohydrates, and particularly RS, in the HAB bread meal Due to the low concentration of available starch in this bread, the size of the HBB serving equivalent to 50 g available starch became large g.
The HBB bread evening meal resulted in a low and prolonged net increment in blood glucose concentration after the standardized breakfast. The appearance of the 0—min blood glucose curve at breakfast after the HBB evening meal bread is probably related to a decreased GER at the time of the breakfast measured as appearance of paracetamol in serum after the breakfast.
The fact that a significant negative correlation was observed between the GER and subjective rating of satiety after the standardized breakfast suggests that the higher satiety obtained after the HBB evening meal was the result of a lower GER.
Such a relation between increased satiety and lowered GER is in concordance with observations by Verdich et al.
A limitation of the conclusions from this study could be that the subjects consumed the test meals in their home and, except from a form to be answered by the subjects, it was not possible to fully control adherence to the written instructions.
For example, not following the instructions regarding the time point for intake of the evening test meals or fasting prior to ingestion of the standardized breakfast may have influenced the results. Another study limitation regarding relations between GI and overnight effects could be that the GI of the test products were not determined but were predicted in vitro.
However, for cereal products, the predicted and measured GI have been shown to correlate well Moreover, the range of predicted GI are coherent with previously published data for similar products In this study, the blood glucose response to the standardized breakfast IAUC 0— min was positively correlated to the f-FFA concentrations.
Such a relation has also been observed in previous studies examining the effects of various test breakfasts at a standardized lunch 24 or from an evening test meal to a standardized breakfast 13 , 25 , respectively.
The reason for the overnight decreased serum FFA with some cereal-based evening meals is not clear, but several factors may be involved. First, a prolonged fed state after low-GI foods related to their improved capacity to reduce the rate of digestion and absorption, thereby maintaining FFA suppressed for a longer time period, has previously been suggested as a mechanism for the improved glucose tolerance from breakfast to a standardized lunch However, in this study, the period between the meals was Second, it is possible that the higher concentration of fasting plasma adiponectin, as seen in the morning after the OB bread evening meal, might have affected the FFA concentrations.
Thus, it has been shown that adiponectin promote an increased rate in clearance of FFA from the blood, hence improving insulin sensitivity 27 , Third, it has been shown that IL-6 stimulates an increase in FFA concentration that may persist for several hours after an acute increase in IL-6 Finally, metabolites produced during colonic fermentation of indigestible carbohydrates may enter the systemic circulation and it has been suggested that SCFA, particularly propionate, may exert systemic effects, including benefits to glucose metabolism 13 , 25 , 30 , 31 and lowered plasma FFA concentrations in humans 32 , In this study, a negative correlation existed between breath H 2 excretion and glucose response IAUC 0— min at breakfast, consistent with the notion that colonic fermentation may be involved in the modulation of overnight glucose tolerance.
Colonic fermentation of indigestible carbohydrates may have implications on glucose tolerance through several mechanisms. According to previous studies in animals, certain DF promotes secretion of GLP-1, an effect suggested to be mediated by bacterial colonic fermentation and formation of SCFA 34 , In addition, our results indicate that colonic fermentation measured by breath H 2 was involved in modulating satiety, possibly through a reduced GER.
A meta-analysis in obese and lean subjects of the effect of GLP-1 on ad libitum energy intake in humans showed increased satiety concomitant with reduced GER, which was suggested to be a contributing factor Furthermore, GLP-1 infusions in that study reduced the energy intake dose dependently in both lean and overweight subjects. In this study, the evening meal consisting of kernel-based barley bread OB bread resulted in lower concentrations of IL-6 and higher concentrations of adiponectin the following morning compared with a WWB evening meal, indicating antiinflammatory properties of the OB bread product.
In conclusion, a cereal-based evening meal with adequate amounts of specific indigestible carbohydrates barley DF and RS was capable of improving glucose excursion and increased the satiety after a sequent standardized high-GI breakfast. Of particular interest is the finding that a mixture of DF and RS added to WWB, simulating the content of these components in the OB bread evening meal, induced similar benefits to overnight glucose tolerance as did the OB bread.
These results suggest that it may be possible to tailor novel low-GI whole-grain foods capable of facilitating glycemic regulation not only at the acute meal but also at a meal ingested 10 h thereafter.
The overnight benefits to glucose tolerance and satiety are probably mediated by mechanisms emanating from colonic fermentation and suggest that specific combinations of indigestible carbohydrates may have prebiotic effects.
The benefits were associated with decreased concentrations of FFA and IL-6 and increased GLP-1 and adiponectin at the time of the breakfast, thus providing evidence for a link between the gut microbial metabolism and key factors associated with insulin resistance. We thank L. Brand-Miller JC. Glycemic load and chronic disease.
Nutr Rev. Google Scholar. A prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women. Am J Clin Nutr. Diabetes Care. Dietary fiber, glycemic load, and risk of non-insulin-dependent diabetes mellitus in women. Whole-grain intake is favorably associated with metabolic risk factors for type 2 diabetes and cardiovascular disease in the Framingham Offspring Study.
Anderson JW. Consequently, metabolic derangement and also obesity has been described as an endotoxemic inflammatory condition triggered by e. Oligofructose has been shown to increase bifidobacteria in obese mice [ 19 ], which was accompanied by improved glucose regulation and a reduced inflammatory tonus [ 20 , 21 ], indicating a prebiotic mechanism.
Less is known about possible colonic mediated effects of DF present in WG diets. A relation between WG intake and improved inflammatory status was reported in a cross-sectional study in healthy subjects [ 22 ].
In addition, certain WG products, rich in cereal DF and resistant starch RS facilitated blood glucose regulation and improved inflammatory tonus in humans in the perspective from a late evening meal to a standardized breakfast, i. The metabolic benefits has been proposed to be associated with colonic fermentation of indigestible carbohydrates DF and RS [ 24 — 26 ], and an associated increase in systemic levels of glucagon-like peptide-1 GLP-1 [ 23 ].
GLP-1 is increasingly being assigned both anti-diabetic and anti-obesogenic features [ 27 — 29 ], which makes it relevant to perform further studies regarding the possible relation between food derived stimulation of this incretin and effects on metabolic parameters. The objective of this work was to evaluate the effect of intrinsic indigestible carbohydrates in boiled barley kernels BK consumed in the evening on glycaemia, appetite sensations, appetite regulatory hormones and voluntary food intake, at fasting and in the post-prandial phase following two consecutive meals breakfast and lunch.
In addition breath hydrogen H 2 excretion was determined as a marker of colonic fermentation. The breakfast and lunch meals were provided ad libitum, allowing for evaluation of over-night effects on metabolism and appetite regulation in a realistic eating situation.
For this purpose, carbohydrate-equivalent meals, consisting of boiled BK or white wheat bread WWB, reference meal , were provided as evening meals to healthy subjects, using a randomized cross-over design. Nineteen healthy volunteers, 6 men and 13 women aged BK, test meal ; One portion All water was absorbed into the kernels.
The BK had the appearance of a rice-analogue and was consumed with — ml water. BM ; Menu choice, program 2 [white bread, g, quick time ]. After cooling, the crust was removed and the bread was sliced and portions At the day of consumption the subjects were instructed to thaw the bread at ambient temperature, still wrapped in aluminium foil and in the plastic bag.
The WWB was consumed with — ml water. The sandwiches were cut in small pieces 6. The subjects were supposed to choose freely the amount ingested. The breakfast was served with ml water. The lunch consisted of Swedish hash i. Water was served with the lunch ml.
The design was randomized cross-over. BK and WWB were included as late evening meals pm , separated by approximately 1 week. Each evening meal was consumed twice, meaning that the test subject participated at four separated occasions. Fasting measurements were performed at all four visits and postprandial measurements were performed at two of the visits randomly chosen , one visit after BK and WWB, respectively. At the days for postprandial measurements, test subjects were provided ad libitum intake of breakfast and lunch, and physiological test variables were repeatedly measured during the experimental day.
Blood glucose, breath H 2 , visual analogue scale VAS ratings for subjective appetite hunger, satiety and desire to eat and samples for measurements of insulin, active ghrelin, total GIP, and active GLP-1 were obtained at fasting and 15, 30, 45, 60, 90, , , , , , , , and minutes after commencing the breakfast.
Samples for IL-6 and adiponectin were collected at 0, 60, , , and minutes and measurements of FFA were performed at time 0 and min.
The subjects were encouraged to standardize their meal pattern and to maintain their regular eating habits during the experimental period. They were also instructed to avoid alcohol, excessive physical exercise or food rich in DF the day prior to the evening test or reference meals.
Furthermore, they should not have taken antibiotics or probiotics during the previous 2 week period. At pm the evening before each experimental day, the subjects prepared and consumed evening meals in their home.
The WWB was distributed as frozen portions; and the uncooked BK were provided in portions ready to cook. The BK meal was prepared according to a detailed written description of the cooking procedure and consumed directly after preparation see above Evening test and reference meals. After the evening meals, the subjects were fasting until the breakfast was served the subsequent morning at the research department. The subjects arrived to the department at am. An intravenous cannula BD Venflon, Becton Dickinson was inserted into an antecubital vein for blood sampling.
Fasting f- blood samples were collected and appetite and breath H 2 registered before the breakfast. Test variables were determined repeatedly in the postprandial period after breakfast and lunch according to time intervals previously stated. The breakfast was consumed at am and finished within 15 min. The lunch was served min after commencing the breakfast. The amounts of breakfast and lunch consumed were registered. During the experimental days 5.
The test- and reference meals were analysed with respect to total starch [ 30 ], available starch [ 31 ], RS [ 32 ], and DF [ 33 ]. Information regarding content of starch and DF in evening test- and reference meals is provided in Table 1. Prior to analysis of total- and available starch, and DF the products were air dried and milled. RS was analysed on products as eaten. Available starch in the BK meal was calculated by subtracting RS from total starch, whereas potentially available starch content in the reference WWB and the commercial white wheat breakfast bread was analysed according to Holm et.
The nutritional composition of the breakfast and lunch meals is displayed in Table 2. Prior to analysis, the breakfast sandwiches were prepared as eaten and then cut into small pieces and freeze dried. The lunch hash was prepared according to instructions and then mixed with addition of water into a paste, followed by freeze drying.
Freeze dried samples were ground in a mortar prior to analysis. Samples were analysed for carbohydrates available starch [ 31 ], protein and fat. Tubes containing inhibition cocktail were kept cold for maximum 6 days until blood sampling.
The blood samples were analysed using immunoassays on the surface of fluorescently labelled microsphere beads and read on the Luminex instrument Luminex Corporation, USA. Plasma and serum for analysis of FFA, IL-6 and adiponectin were allowed to clot in ambient temperature serum or kept on ice and centrifuged within 30 minutes plasma. The incremental area- and area under the curve iAUC and AUC, respectively was calculated for each subject and test meal, using the trapezoid model.
Incremental peak iPeak concentrations were calculated for glucose and insulin as individual maximum postprandial increase from baseline. For calculation of incremental responses, the specific fasting value at the day for postprandial measurements was used. If the value from a test subject were missing for one of the products, the test subject was excluded from that specific calculation.
For breath hydrogen where the variation in the concentration scarcely changed over time, a weighted mean were produced by calculating a mean for equal time intervals 1 mean per hour over the test period, and then a mean for the different hours were calculated and used in statistical analysis.
The glucose profile GP 2 is calculated as the time min during which the blood glucose are above fasting concentration divided with the squared incremental peak value mM of blood glucose for each test subject and test meal.
In the cases where the blood glucose concentration remained above fasting for the entire min, the duration value was set to min.
GP 2 is used as a measure of the course of glycaemia including also characteristics in the late postprandial phase, high values are considered beneficial [ 34 ]. Breath H 2 excretion during the experimental day. Mean postprandial H 2 excretion Dotted lines at the y-axes indicate weighted mean calculated for WWB 8.
Ad libitum energy intake at breakfast was kcal and kcal following BK and WWB evening meal, respectively, with no significant difference depending on the previous evening meal Table 4.
No differences were seen in f-glucose- or f-insulin concentrations depending on previous evening meals Table 3. No significant differences were observed in the post-prandial response of insulin depending on evening meals Figure 2 , Table 5.
Incremental blood glucose and plasma insulin response. BK, barley kernel; WWB, white wheat bread. No significant differences were observed prior to lunch min in FFA depending on the preceding evening meal BK 0. No significant differences were detected in the post-prandial ghrelin response Table 6 , Figure 4. Soluble fiber dissolves in water as it passes through your intestines. Consequently, it becomes gel-like and sticky, which causes it to bind to bile and remove it from your body.
Soluble fiber also slows down digestion, delays the emptying of your stomach and contributes to making you feel full, which may help control weight. An example of a soluble fiber is inulin, found in abundance in yams, which stimulates the growth of friendly intestinal bacterial.
Insoluble fiber is the other main type of dietary fiber that is indigestible. Lignans are a group of insoluble fibers found commonly in cereal grains such as wheat, rye, barley and oats.
Lignans help to control the release of glucose into your bloodstream. Plant-based foods contain both types of dietary fibers in varying degrees.
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