Wie viel Kontrolle ist möglich?

Zusammenfassung

Über 90 % aller Tumorerkrankungen sind exogen bedingt; Schätzungen zufolge könnten 2 Drittel aller Tumorerkrankungen durch Ernährung und Lebensstil verhindert werden. Daten aus Tierexperimenten und In-vitro-Untersuchungen zeigen, dass die intestinale Mikrobiota an der Entstehung von Dickdarmtumoren beteiligt ist. Dabei spielen mehrere Mechanismen eine Rolle, unter anderem die Aktivierung von Prokarzinogenen durch bakterielle Enzyme. Beim Menschen ist ein Einfluss der Darmbakterien auf die Tumorentstehung wahrscheinlich. Bestimmte Spezies sind mit einem erhöhten Risiko assoziiert, andere sind als protektiv einzustufen. Die Zusammenhänge sind jedoch komplex und nicht abschließend geklärt. Übergewicht, Alkohol, Rauchen sowie ein hoher Verzehr von rotem Fleisch und Fleischwaren erhöhen mit eindeutiger Evidenz das Risiko für Dickdarmtumoren. Ballaststoffreiche Lebensmittel, Milch und eine gute Kalziumversorgung sowie regelmäßige Bewegung wirken dem entgegen. Durch den Einsatz dieser Schutzfaktoren ist es möglich, die Karzinogenese auf verschiedenen Stufen zu blockieren oder zu verlangsamen. Obwohl es bisher keine direkte experimentelle Evidenz für die Verminderung von humanen Tumorerkrankungen durch den Verzehr von probiotischen Kulturen gibt, sprechen mehrere indirekte Belege für deren chemoprotektives Potenzial.

Abstract

More than 90 % of all tumour disorders have exogenous causes. According to estimates, two-thirds of all tumour disorders could be prevented by means of diet and lifestyle. Data from animal experiments and in vitro studies have shown that the intestinal microbiota is involved in the development of tumours of the large intestine. Several mechanisms have a role in this – among others, procarcinogen activation through bacterial enzymes. In humans, gut bacteria are likely to have an influence on the genesis of tumours. Certain species are associated with an increased risk, others can be categorised as protective. However, the associations are complex and ultimately not completely clear. The evidence that overweight, alcohol, smoking, and consumption of large amounts of red meat and meat products increase the risk for cancers of the large intestine is unequivocal. Fibre-rich foods, milk, and a good calcium supply, as well as regular exercise, counteract these risk factors. By using such protective factors it is possible to block carcinogenesis at various stages or at least slow it down. Although thus far, no direct experimental evidence exists that ingestion of probiotic cultures leads to a reduction in human tumour disorders, several instances of indirect evidence speak in favour of their chemoprotective potential.

Schlüsselwörter

Karzinogenese - Darmbakterien - heterozyklische aromatische Amine - β-Glukuronidase - Ernährung - Risikofaktoren - Schutzfaktoren

Keywords

carcinogenesis - gut bacteria - heterocyclic aromatic amines - β-glucuronidase - nutrition - risk factors - protective factors

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