Probiotics in cancer prevention

Abstract

Probiotics have been given credit for numerous health-promoting effects; one of which is their anticarcinogenic properties. Even when the epidemiological data and those obtained from human trails are promising, animal models are still necessary to elucidate the mechanisms by which they can act. The effects of probiotics on intestinal disorders have been the most extensively studied. In a model of colon cancer inhibition through yoghurt feeding, yoghurt exerts its antitumor activity through different mechanisms: 1) modulates the immune system response and exerts an anti-inflammatory effect in the large intestine; 2) activates apoptosis pathways; and 3) decreases certain enzyme activities involved in the development of tumors in the intestine. The introduction of antioxidant enzyme genes in probiotic strains that have natural anti-inflammatory properties could generate very potent strains that could be used for the prevention of inflammatory diseases or post-cancer drug treatments. It is also possible to obtain a beneficial effect in other mucosal site distant to the intestine with the oral administration of a probiotics or fermented milks. Fermented milk administration can regulate the immune response in an estrogen- dependent breast tumor model. Probiotic strain selection plays an important role in the antitumoral effects observed and the principal cause that can be attributed to the probiotic and / or fermented product against cancer is the immune surveillance, which differs according to the site where the tumor attacks.