Postprandial glucose metabolism and SCFA after consuming wholegrain rye bread and wheat bread enriched with bioprocessed rye bran in individuals with mild gastrointestinal symptoms

Abstract

BackgroundRye bread benefits glucose metabolism. It is unknown whether the same effect is achieved by rye bran-enriched wheat bread. We tested whether white wheat bread enriched with bioprocessed rye bran (BRB + WW) and sourdough wholegrain rye bread (WGR) have similar effects on glucose metabolism and plasma level of short chain fatty acids (SCFAs).MethodsTwenty-one (12 women) of 23 recruited subjects completed an intervention with a four-week run-in and two four-week test periods in cross-over design. White wheat bread (WW; 3% fibre) was consumed during the run-in, and WGR and BRB + WW (10% fibre) during the test periods. A meal test providing 51/33/11 E % from carbohydrates/fat/protein was conducted at the end of each period. Fasting and postprandial plasma samples were analysed for glucose, insulin, and SCFA.ResultsGlucose and insulin responses and plasma concentrations of SCFAs to the meal test were similar between the WGR and BRB + WW periods. When compared to the WW period, postprandial insulin concentration at 120 min was lower (p = 0.023) and the first-phase insulin secretion improved (p = 0.033) only after the WGR period, whereas postprandial concentrations of butyrate (p < 0.05) and propionate (p = 0.009) at 30 min increased during both rye bread periods.ConclusionsBeneficial effects of WGR over white wheat bread on glucose and SCFA production were confirmed. The enrichment of the white wheat bread with bioprocessed rye bran (BRB + WW) yielded similar but not as pronounced effects than WGR when compared to WW alone. Postprandially measured glucose metabolism and concentrations of SCFAs provided additional information along with fasting measurements.

Effects of fibre-rich rye milling fraction on the functional properties and nutritional quality of wholemeal rye bread

“…The supplemented breads had significantly lower RAG content than the CB, but the SDI values of all breads were similar. Ingestion of bread with a high RAG content might cause a rapid increase of plasma glucose and insulin levels, which have been associated with health complications such as diabetes, cardiovascular disease, and obesity (Englyst et al 1996;Lappi et al 2014). Englyst et al (1996) analysed the nutritionally important starch fractions content and glycemic index (GI) of 39 commonly used starchy foods.…”

“…Several small human feeding studies have investigated the biological effects of DF-enriched breads. For example, a few studies examined the effect of wholemeal rye bread on blood cholesterol, postprandial glucose metabolism and insulin secretion, and bowel function (McIntosh et al 2003;Lappi et al 2014). The conclusion from these and several epidemiological studies was that increased consumption of breads and other cereal products with high nutritional quality could contribute to improved health outcomes for consumers.…”

Dietary fibers and associated phytochemicals in cereals

“…A reduced rate of glucose absorption as expressed in the glycemic index (GI) can be obtained when consuming WG cereals with a high content of β‐glucan, i.e. oats and barley , whereas rye in spite of relatively high levels of soluble AX does not seem to influence the rate of glucose absorption to any significant degree either in human or animal studies . The starch structure (amylose, amylopectin), the presence of intact kernels and other macronutrients can, however, be as important for the rate of glucose absorption as the DF .…”

Targeted metabolomics reveals differences in the extended postprandial plasma metabolome of healthy subjects after intake of whole‐grain rye porridges versus refined wheat bread

“…In this study, NMR‐based targeted metabolomics and GC‐MS analysis (particular for SCFAs) were used to investigate putative differences in 38 plasma metabolites (intra‐ and inter‐batch CV <15%) after consumption of abovementioned WG rye porridges and refined wheat bread. The majority of metabolites analyzed by our targeted metabolomics approach have previously been associated with WG‐rich diet intake, including essential amino acids (EAAs) and their catabolic products , ketone bodies , colonic fermentation products (SCFAs) , glycolytic and TCA intermediates , and other metabolites, such as dimethylglycine, choline, betaine, which have been comprehensively emphasized in recent published reviews (Supporting Information Table S3).…”

“…S2), a phenomenon known as the ‘second meal effect’ . SCFAs, which are formed during gut fermentation of dietary fiber, have been proposed as important candidates involved in second meal glucose reduction . Acetate, propionate, and butyrate are the most abundant SCFAs presenting in circulation (≥95%).…”