Incretins in satiety
There is a growing insight regarding the role of the gut microflora and gut fermentation as modulator of metabolism, appetite regulation, systemic low-grade inflammation, and obesity. The metabolic “crosstalk” between the gut and peripheral tissues has been suggested to be regulated through colonic fermentation of specific indigestible carbohydrates, i.e. prebiotic dietary fibre. Involved in this cross-talk are several hormones (e.g. GLP-1 and PYY) released in the gut. These hormones play an important role in e.g. glucose- and energy regulation. Both GLP-1 and PYY are considered as anti-diabetic and anti-obesity hormones, and GLP-1-based therapies are currently used as a novel treatment for type 2 diabetes. This novel knowledge makes prebiotic dietary fibre a promising approach for prevention and treatment of metabolic diseases. However, the cardiometabolic benefits differ depending on sources and combinations of dietary fibre, and still there is very scarce information available concerning effects in humans in this respect.
We have clearly revealed anti-diabetic potential of specific indigestible carbohydrates in barley kernel based products and brown beans. Several cardiometabolic risk marker were improved in a semi-acute (11-16 h) time perspective where test products were consumed in the evening and cardiometabolic risk markers determined at fasting the next morning and postprandially after a standardised breakfast . For example, glucose regulation was improved after barley kernels based products and beans, and also the insulin economy was improved. Another important finding was a substrate induced increase plasma levels of GLP-1, extending from about 11-16 h after ingestion of the test meal. Moreover, the project has revealed that barley dietary fibreand/or brown beans stimulate also several other appetite regulatory hormones, e.g. PYY, and decrease the voluntary energy intake, while simultaneously reducing perceived hunger. Interestingly we have found that indigestible carbohydrates in the described products may possess anti-inflammatory properties. This is an important finding since a state of increased low grade chronic inflammation is a recognized cardiometabolic risk factor, making food concepts with anti-inflammatory properties promising in prevention. Simultaneously to the benefits seen on risk markers, we measured increased breath hydrogen excretion. Breath hydrogen is a marker of increased fermentation activity in colon, and connects the beneficial effects we observed with mechanisms originating from colonic fermentation. Also an increased production of short chain fatty acids (SCFA) was detected after barley based products and brown beans. SCFA are produced during colonic fermentation of fermentable indigestible carbohydrates, and in addition to providing energy to colonic enterocytes, SCFA also function as signaling molecules and may be involved in mediating some of the beneficial effects described above. GLP-2 is another important gut hormone which we found to increase in an over-night perspective after meal with barley kernels based products. GLP-2 is involved in improving gut mucosa barrier and thereby prevents toxic compounds to enter the systemic circulation and increase inflammation.
Project leader: PhD Anne Nilsson.