Treffpunkt Darm

Zusammenfassung

Mikrobiom-Analysen zufolge sind Gene des Kohlenhydratstoffwechsels im humanen Darmmikrobiom überrepräsentiert. Dementsprechend verfügen Darmbakterien über ein breites Spektrum an Enzymen, die den Abbau von Ballaststoffen ermöglichen. Hauptsubstrat der Darmbakterien sind resistente Stärken, gefolgt von Nicht-Stärke-Polysacchariden wie Cellulose, Hemicellulose und Pektin. Bei der Fermentation entstehen unter anderem kurzkettige Fettsäuren wie Acetat, Propionat und Butyrat. Insbesondere Butyrat liefert nicht nur Energie, sondern übt auch regulatorische Funktionen aus. Daten aus epidemiologischen Studien sprechen dafür, dass eine ballaststoffreiche Ernährung das Darmkrebsrisiko senkt. In-vitro-Studien zeigen, dass bakteriell gebildete Buttersäure dabei eine Rolle spielen könnte: Sie hemmt die Proliferation von Krebszellen und induziert die Zelldifferenzierung. Darüber hinaus werden Effekte kurzkettiger Fettsäuren mit der Prävention des metabolischen Syndroms in Verbindung gebracht. Ballaststoffreiche Diäten korrelieren mit erhöhten Spiegeln des Appetit senkenden Hormons Peptid YY (PYY) und GLP-1 (Glucagon-like-peptide), das die Insulinsekretion in den Pankreaszellen und die Insulinsensitivität in den Zielgeweben positiv beeinflusst.

Abstract

Microbiome analyses have shown that genes of the carbohydrate metabolism are overrepresented in the human gut microbiome. Accordingly, gut bacteria contain a wide spectrum of enzymes that enable the breakdown of dietary fibres. The main substrates for the gut bacteria are resistant starches, followed by non-starch polysaccharides such as cellulose, hemicellulose, and pectin. During fermentation, short-chain fatty acids develop, such as acetate, propionate, and butyrate, among others. According to data from epidemiological studies, a diet rich in fibres lowers the risk of bowel cancer. In vitro studies have shown that bacterially produced butyrate may have a role in this, as it inhibits the proliferation of cancer cells and induces cell differentiation. Furthermore, the effects of short-chain fatty acids are associated with the prevention of the metabolic syndrome. Diets rich in fibre correlate with higher concentrations of the appetite-lowering hormone peptide YY (PYY) and GLP-1 (glucagon-like peptide), which has a positive effect on insulin secretion in the pancreatic cells and insulin sensitivity in the target tissues.

Schlüsselwörter

Mikrobiom - bakterielle Abbauwege - kurzkettige Fettsäuren - Dickdarmkrebs - Diabetes - FFA2-Rezeptoren

Keywords

microbiome - bacterial degradation pathways - short-chain fatty acids - bowel cancer - diabetes - FFA2 receptors

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