Cancer may be the most dreaded word in the English lexicon.
Even as people survive longer with some cancers these days, thanks to early diagnosis and better treatments, a larger percentage of the global population will eventually get cancer. Indeed, more tumors pop up as we age–and we are living longer– and also the environment is swarming with carcinogens like never before in history.
A quick review of the 3 phases of cancer:
- Initiation, in which toxic compounds or mutagens damage genetic material, setting the stage for cancer activation.
- Promotion, in which mucosa is irritated and cells proliferate.
- Progression, the final stage when a previously benign polyp, for example, becomes a malignant tumor.
Probiotics may possibly interfere at several stages.
In the initiation phase:
- probiotics may inhibit or deactivate enzymes which create toxins from foods
- probiotics may bind to mutagens, making them less likely to be absorbed (an example is Lactobacillus acidophilus which binds with the nasty heterocyclic amines formed in meats cooked at high temperatures) Tip: Serve yogurt at your next barbeque
- Probiotic byproducts such as fatty acids make an acidic colon, a pH less welcoming to cancer.
In the promotion phase:
- Probiotics may reduce inflammation and pre-cancer cell formation
In progression, the moment of truth when cancer appears:
- Again, metabolites of the microbes in our guts may interrupt or interact with key processes in cancer cell proliferation and cell death.
Colon cancer is the most studied in respect to probiotics.
Cancer develops in the colon as a result of interplay between diet, intestinal microbes and mucosa as well as genetic factors. Both animal and human studies suggest that probiotics may help prevent colon cancer and even stop its progression. A Portuguese review of the literature from 2003 to 2008 showed clearly: an inverse relation between the consumption of probiotics and prebiotics in colon cancer diagnosis through various action mechanisms, including: immune response stimulation, reduction in inflammation, inhibition of formation of tumor cells and conversion of pre-carcinogenic substances into carcinogenic ones.
For a more in-depth view of the mechanisms by which bacteria may induce carcinogenesis–inflammation, immune evasion, and immune suppression—see this work from Federico II University of Naples in Italy.
The authors write:
“The emerging relationship between gut microbiota and cancer has prompted new ways of thinking about cancer prevention and has led to the development of noninvasive diagnostic tests and innovative treatments, such as with probiotics. However, although in vitro and animal model studies suggest a protective anticancer effect of probiotics, the results of human epidemiological studies are controversial.”