Key Points
- Probiotics prevent the buildup of abnormal, precancerous lesions in the colon called aberrant crypt foci.
- Probiotics reduce oxidative stress — damage to cells from deleterious, unstable molecules called free radicals — in the colon, which may suppress aberrant crypt foci.
- At the cellular level, probiotics cut down colonic levels of a protein with elevated abundance in cancerous tissue — ꞵ-catenin — suggesting probiotics prevent colorectal cancer cell growth.
Aside from skin cancers, colorectal cancer is the third most common cancer type, accounting for an expected 52,550 deaths in the US in 2023. Researchers have attributed non-hereditary colorectal cancer onset to poor dietary choices and shoddy gut microbial composition, with increased abundance of detrimental gut bacterial species like Eschericia coli. Low-quality dietary choices and potentially harmful gut microbes induce inflammation from oxidative stress, precipitating cancer. Along those lines, identifying potentially beneficial bacteria (probiotics) along with natural compounds to prevent colorectal cancer onset has become crucial.
Published in Cancers, de Vasconcelos and colleagues from Federal University of Ceará in Brazil show that probiotics alone and with pterostilbene reduce the number of aberrant crypt foci that lead to cancer formation in colon tissue of rats treated with the carcinogen 1,2-dimethylhydrazine. Moreover, the probiotics and pterostilbene combination reduces levels of a molecular marker for oxidative stress, malondialdehyde, and increases the antioxidant glutathione. At the cellular level, probiotics alone or with pterostilbene diminish colon cell levels of a protein marker for cancer — ꞵ-catenin. These findings suggest that probiotics reduce the prevalence of aberrant crypt foci in colon tissue to prevent cancer and that, when combined with pterostilbene, can suppress colon oxidative damage.
Probiotics with Pterostilbene Reduce Oxidative Stress and Prevent Colorectal Cancer
To better understand whether supplementing with probiotics and/or pterostilbene affects colorectal cancer, de Vasconcelos and colleagues examined colon tissue aberrant crypt foci. After exposing rats to a cancer-inducing carcinogen, they found that deeper colonic segments from the stomach (medium and distal) as opposed to shorter depths (proximal) contained significantly more aberrant crypt foci after carcinogen treatments. Treating these rats with probiotics alleviated aberrant crypt foci accumulation in the medium and distal segments, while probiotics and pterostilbene diminished these foci only in the medium segment. These findings suggest that deeper colonic segments have higher numbers of carcinogen-induced aberrant crypt foci. Moreover, probiotic treatments ameliorated these foci, and the addition of pterostilbene didn’t have much of an effect.
To better grasp how probiotics influence oxidative stress, the Brazilian researchers examined malondialdehyde and glutathione levels in the colon. They found that the probiotics with added pterostilbene reduced malondialdehyde levels, a marker of oxidative stress. Furthermore, probiotics with pterostilbene significantly increased levels of the antioxidant glutathione. These findings suggest that probiotics and pterostilbene act synergistically to alleviate oxidative stress and promote higher antioxidant levels.
The Brazilian researchers sought to determine whether probiotics and/or pterostilbene reduce the number of colon cells that contain a protein marker for cancer — ꞵ-catenin. The researchers found that pterostilbene alone didn’t statistically reduce ꞵ-catenin but that probiotics alone and with pterostilbene did. These data show that probiotics alone and with pterostilbene reduce the accumulation of this protein marker for cancer, however, pterostilbene wasn’t necessary for this effect. Thus, probiotics can potentially slow cancer growth as shown by the reduction in the accumulation of ꞵ-catenin.
Identifying Optimal Probiotic and Pterostilbene Doses to Prevent Cancer
The study’s data provide evidence for using probiotics, like the one containing Lactobacillus acidophilus and Lactobacillus bifidum used in the study, to reduce colonic aberrant crypt foci and suppress potential colorectal cancer growth. Although adding pterostilbene to probiotics increased levels of the antioxidant glutathione, the results don’t show that the addition of pterostilbene reduced aberrant crypt foci numbers or inhibited levels of the protein marker for cancer — ꞵ-catenin. Thus, the study’s most significant findings were that probiotics can reduce aberrant crypt foci to potentially slow colorectal cancer growth in rats.
Future probiotics research should find what proportions of bacterial species work best to promote gut health and prevent colorectal cancer. Moreover, research should examine whether different pterostilbene dosages than the ones used in the study can work to prevent colorectal cancer on its own or synergistically when combined with probiotics. Although this study didn’t necessarily confirm a synergistic benefit of probiotics with pterostilbene, perhaps other pterostilbene dosages would improve probiotics’ effects on gut health.
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