High fiber rye foods decrease body weight and body fat and affect metabolic risk markers

Overweight and obesity are major risk factors for development of non-communicable diseases, such as type-2 diabetes and cardiovascular disease, and increase the risk of early mortality. Diet and food consumption are among the most important factors in preventing and reversing overweight, obesity and their comorbidities. Whole grain has been associated with decreased risk of overweight and obesity in observational studies, but the results from interventions are inconsistent. This may be because very few interventions have been adequately designed for evaluation of the effects of whole grain on body weight management and these effects may differ between different whole grain sources. Rye is the cereal with the highest fiber content and has been suggested to be superior to wheat in inducing beneficial physiological effects with health implications, but large randomized controlled trials with well-characterized intervention foods are lacking. This thesis aimed to investigate the effects of rye-based cereals, compared with refined wheat-based cereals, on body weight loss and metabolic risk factors. Furthermore, the potential influence of subjective appetite and gut microbiota were investigated. High fiber rye-based cereal products were shown to induce greater reduction in body weight and body fat than corresponding refined wheat products after 6 and 12 weeks of intervention among overweight and obese men and women. No consistent effect of rye products on appetite response was found and the changes in body weight and body fat could not be linked to differences in subjective appetite or food intake. However, this may be due to methodological issues and warrants further research. Compared with refined wheat products, high fiber rye-based cereal products were shown to lower C-reactive protein, a marker of inflammation and a risk factor for cardiovascular disease, in two different populations. This effect was associated with reduction in abundance of certain bacteria in the gut that have previously been associated with decreased gut barrier integrity, suggesting that the effect of rye consumption on inflammation may, at least partly, be mediated through changes in gut microbiota composition and decreased gut permeability. In conclusion, the work included in this thesis suggests that replacing wheat-based cereals with high fiber rye-based cereals can aid the reduction of body weight and body fat, and reduce low-grade inflammation. These results can support the development of dietary guidelines and promote the development of healthier food products

The Effect of Rye-Based Foods on Postprandial Plasma Insulin Concentration: The Rye Factor

Consumption of whole grain has been associated with lower incidence of type-2 diabetes, cardiovascular disease and their risk factors including improved glycemic control. In comparison with other whole grain products, rye bread has been shown to induce lower insulin response in the postprandial phase, without affecting the glucose response. This phenomenon has been referred to as the "rye factor" and is being explored in this review where we summarize the findings from meal and extended meal studies including rye-based foods. Overall, results from intervention studies showed that rye-based foods vs. (wheat) control foods had positive effect on both insulin and glucose responses in the postprandial phase, rather than on insulin alone. Mechanistic studies have shown that the rye factor phenomenon might be due to slowing of the glucose uptake in the intestine. However, this has also been shown for wheat-based bread and is likely an effect of structural properties of the investigated foods rather than the rye per se. More carefully controlled studies where standardized structural properties of different cereals are linked to the postprandial response are needed to further elucidate the underlying mechanisms and determinants for the effect of specific cereals and product traits on postprandial glycemic control

The Effects of High Fiber Rye, Compared to Refined Wheat, on Gut Microbiota Composition, Plasma Short Chain Fatty Acids, and Implications for Weight Loss and Metabolic Risk Factors (the RyeWeight Study)

Consumption of whole grain and cereal fiber have been inversely associated with body weight and obesity measures in observational studies but data from large, long-term randomized interventions are scarce. Among the cereals, rye has the highest fiber content and high rye consumption has been linked to increased production of gut fermentation products, as well as reduced risks of obesity and metabolic disease. The effects on body weight and metabolic risk factors may partly be mediated through gut microbiota and/or their fermentation products. We used data from a randomized controlled weight loss trial where participants were randomized to a hypocaloric diet rich in either high fiber rye foods or refined wheat foods for 12 weeks to investigate the effects of the intervention on gut microbiota composition and plasma short chain fatty acids, as well as the potential association with weight loss and metabolic risk markers. Rye, compared to wheat, induced some changes in gut microbiota composition, including increased abundance of the butyrate producing Agathobacter and reduced abundance of [Ruminococcus] torques group, which may be related to reductions in low grade inflammation caused by the intervention. Plasma butyrate increased in the rye group. In conclusion, intervention with high fiber rye foods induced some changes in gut microbiota composition and plasma short chain fatty acid concentration, which were associated with improvements in metabolic risk markers as a result of the intervention

Evaluation of Subjective Appetite Assessment under Free-Living vs. Controlled Conditions: A Randomized Crossover Trial Comparing Whole-Grain Rye and Refined Wheat Diets (VASA-Home)

Background: Accurate assessment of self-reported appetite under free-living conditions is warranted to conduct large-scale intervention studies measuring appetite at a feasible cost. However, the performance of visual analogue scales (VASs) for this purpose has not been widely examined. Method: This randomized crossover trial was conducted to evaluate VASs in free-living vs. clinic-based settings and to assess appetite response following hypocaloric whole-grain rye and refined wheat diets. Twenty-nine healthy adults with overweight or obesity continuously answered VAS questions about their perceived appetite from morning to evening. Results: No differences in whole-day VAS scores (primary outcome) between clinic-based and free-living settings were observed, whereas measures of total area under the curve (tAUC) showed increased fullness in clinic-based interventions of 7% (p < 0.008) for whole-day responses and 13% (p < 0.03) following a snack. Appetite responses for a whole day did not differ between diets whereas rye-based dinners induced 12% (p < 0.016) higher fullness and reduced hunger by 17% (p < 0.02) irrespective of setting. A reduction in hunger of 15% (p < 0.05) was also observed following rye-based vs. wheat-based lunches. Conclusion: The results suggest that the VAS is valid for evaluation of appetite responses between diets under free-living conditions. No difference in self-reported appetite over the whole day was found after whole-grain rye vs. refined wheat-based diets, but there were some suggested differences at certain postprandial periods, in individuals with overweight or obesity

Appetite and Subsequent Food Intake Were Unaffected by the Amount of Sourdough and Rye in Soft Bread-A Randomized Cross-Over Breakfast Study

Sourdough fermented bread has been suggested to have beneficial health effects, in part mediated by increased satiety in the postprandial phase, but only limited research has been conducted to verify this. The current study aimed to investigate the effect of the amounts of sourdough and rye in soft bread on postprandial appetite. On 6 occasions, 23 healthy volunteers consumed 5 different test breads, with varying amount of rye and sourdough, and a yeast-fermented refined wheat control bread as part of a breakfast meal. The sourdough ranged between 9⁻51% of dough weight and rye content between 35⁻48% of flour weight. Appetite was recorded using visual analogue scales from immediately before breakfast and every 30 min the following 4 h. An ad libitum lunch was served 4 h after the breakfast meal, from which voluntary energy intake was measured. While some of the test breads resulted in lower hunger ratings and increased sense of fullness compared to the refined wheat bread, there were no differences between the test breads. The content of rye in the test breads differed within a narrow range, which might explain the lack of a consistent effect of rye on appetite. Microstructural examination of the test breads showed an increased aggregation of proteins in the breads with high content of sourdough, indicating additional changes to the breads, beyond change in pH, which may counteract the potential effect of decreased pH in the bread on appetite. In conclusion, our study does not support an effect of sourdough on appetite and ad libitum food intake

Appetite and Subsequent Food Intake Were Unaffected by the Amount of Sourdough and Rye in Soft Bread-A Randomized Cross-Over Breakfast Study.

Sourdough fermented bread has been suggested to have beneficial health effects, in part mediated by increased satiety in the postprandial phase, but only limited research has been conducted to verify this. The current study aimed to investigate the effect of the amounts of sourdough and rye in soft bread on postprandial appetite. On 6 occasions, 23 healthy volunteers consumed 5 different test breads, with varying amount of rye and sourdough, and a yeast-fermented refined wheat control bread as part of a breakfast meal. The sourdough ranged between 9–51% of dough weight and rye content between 35–48% of flour weight. Appetite was recorded using visual analogue scales from immediately before breakfast and every 30 min the following 4 h. An ad libitum lunch was served 4 h after the breakfast meal, from which voluntary energy intake was measured. While some of the test breads resulted in lower hunger ratings and increased sense of fullness compared to the refined wheat bread, there were no differences between the test breads. The content of rye in the test breads differed within a narrow range, which might explain the lack of a consistent effect of rye on appetite. Microstructural examination of the test breads showed an increased aggregation of proteins in the breads with high content of sourdough, indicating additional changes to the breads, beyond change in pH, which may counteract the potential effect of decreased pH in the bread on appetite. In conclusion, our study does not support an effect of sourdough on appetite and ad libitum food intake

Whole Grains and Appetite

Consumption of whole grain has been suggested to decrease the risk of obesity, indicated by a decreased weight or weight gain in prospective studies. Appetite sensation may be affected during or immediately after whole grain consumption, potentially mediated by mechanisms related to stomach distension or a lower glycemic response. Various single-meal studies have investigated the effects of different types of whole grain products on subjective appetite sensation and ad libitum energy intake at a subsequent meal in acute settings. The presence of dietary fibre and resistant starch as well as the firmer botanical structure of whole grain foods may impair digestion and absorption in the small intestine, which increases the passage of macronutrients to the colon. Factors such as dietary fibre content and composition, particle size and cereal type may determine effects on appetite. Consumption of certain whole grain foods has been reported to influence appetite sensation after the following meal, the so-called “second-meal effect.

Whole-grain rye and wheat affect some markers of gut health without altering the fecal microbiota in healthy overweight adults: A 6-week randomized trial

Whole grains have shown potential for improving gut health, but evidence comparing different whole-grain types is lacking. Objective:We investigated whether whole-grain wheat (WGW) and whole-grain rye (WGR) improve gut health in different ways compared to refined wheat (RW), with the primary outcomes of microbiota composition and gastrointestinal (GI) symptoms. Methods: In a randomized parallel trial, 70 healthy adults (in means \ub1 SDs; aged 51.0 \ub1 9.4 y, body mass index [BMI (in kg/m2)] 27.8 \ub1 1.9, 32:38 men:women) replaced cereal foods from their habitual diet with WGR, WGW, or RW (control). Before and after a 6-wk intervention, a spot stool sample was collected and analyzed for short-chain fatty acids and microbiota composition through the use of 16S ribosomal RNA gene-targeted high-throughput amplicon sequencing. GI symptoms and stool regularity were evaluated by questionnaires at baseline and after weeks 2, 4, and 6. Results: Intakes of whole grains were 145.2 \ub1 75.9, 124.2 \ub1 57.3, and 5.4 \ub1 3.2 g/d in the WGW, WGR, and RW groups, respectively. Gut microbiota composition was not affected by diet. The relative change in fecal butyrate decreased in the RW (238%) group compared to the WGW (25%, P = 0.014) and WGR groups (21%, P = 0.037). Other short-chain fatty acids were unaffected. Flatulence was more frequent following intake of WGW (OR: 2.06, 95% CI: 1.03, 4.17) and WGR (OR: 2.62, 95% CI: 1.35, 5.22) compared to RW, whereas bloating was less frequent following WGW (OR: 0.38, 95% CI: 0.18, 0.80) and WGR (OR: 0.34, 95% CI: 0.16, 0.72). Stool frequency increased following WGR but not WGW, compared to RW in weeks 2 (0.4 defecations/d, P = 0.049) and 4 (0.5 defecations/d, P = 0.043), but not in week 6. The WGW and WGR groups did not differ from each other in any of the variables tested. Conclusion: Regular consumption ofWGR andWGWaffected fecal butyrate concentration and gastrointestinal symptoms in healthy overweight adults, supporting the hypothesis thatWGR andWGWcan be included in the diet equally tomaintain gut health

The effects of fermented rye products on gut microbiota and their association with metabolic factors in Chinese adults - an explorative study

Rye is among the cereals with the highest content of dietary fibre. A high rye food intake has been associated with improved metabolic risk factors in some but not all observational and intervention studies. Whole-grain rye has also been suggested to affect the gut microbiota in individuals with metabolic syndrome. However, it is yet unclear to what extent effects on the gut microbiota mediate the beneficial metabolic responses of whole-grain rye intake. We hypothesized that a high intake of whole grain rye products containing fermented rye bran (FRB) vs. refined wheat based products (RW) could alter the gut microbiota and short-chain fatty acid (SCFA) composition towards a phenotype associated with beneficial metabolic effects in a population not used to such foods. For this purpose, we conducted a post hoc analysis of a 12-week randomized controlled trial in Chinese adults with Helicobacter pylori (HP) infection, with 53 participants consuming RW and 31 participants consuming FRB included in the analysis. Anthropometric measurements and fasting blood and fecal sample analyses as well as C-13-urea breath test were performed at baseline and after a 12-week intervention. At week 12, we observed a higher serum insulin concentration (P-value = 0.038) in the FRB group (n = 31) versus the RW group (n = 53), and this difference was corroborated with alterations in the genus-level relative abundances of the gut microbiota, represented by an increase in Romboutsia and a reduction in Bilophila in the FRB group (n = 22) versus the RW group (n = 46). Compared to the RW group (n = 53), fecal acetic acid concentration was significantly higher in the FRB group (n = 31) at week 12. We also found that fecal acetic and butyric acids positively, while isobutyric, isovaleric and 2-methylbutyric acids inversely, correlated with the gut Romboutsia level among all participants (n = 68) at week 12. We found positive correlations of fecal isobutyric, isovaleric and 2-methylbutyric acids with gut Bilophila (n = 68). In conclusion, our results suggest that the intake of high-fibre rye products could modify gut Romboutsia and Bilophila in a Chinese population with HP infection. These effects are paralleled with favorable modifications of the SCFA concentration and are associated with altered glycemic traits