Over the years, probiotics, an example of a functional food, have been the focus of intense research activity in recent years and have been defined as ?living micro-organisms which upon ingestion in certain numbers exert health benefits beyond inherent general nutrition? Research published in the January 2011 issue of the Proceedings of the National Academy of Sciences (PNAS) suggest that probiotics may offer the possibility of safe, drug-free treatment in combating colon cancer.
Probiotics usually refers to a number of highly selected lactic acid bacteria. These bacteria have unique gut-survival properties. For many years, these bacteria have been included in a number of fermented milk products and dietary supplement. Based on ongoing clinical trial beneficial effects have been attributed to probiotic bacteria, including the alleviation of lactoseintolerance symptoms, the reduction of serum cholesterol and anticancer effects.  Especially in colorectal cancer (CRC) have the effects of probiaticts been extensively researched.
Incidence and mortality of CRC
Colorectal Cancer is a major public health problem in many Western Countries. Despite excellent screening and preventive strategies, the American Cancer Society (ACS) reported that, in 2009, 146,970 people were diagnosed with CRC of which 49,920 died. This makes CRC the third most common type of cancer in both sexes (after prostate and lung cancers in men and lung and breast cancers in women) and the second most common cause of cancer death in the United States. Furthermore, mortality from CRC has shown little sign of decreasing in the last 20?30 years. Research has shown that diet makes an important contribution to CRC risk (World Cancer Research Fund/American Institute for Cancer Research1997) implying that the risks of CRC are potentially reducible .
A Powerful Treatment Option
While the probiotics in many ?fictional foods,? including many types of yogurt, have been labeled healthful, now it appears they may also be a powerful treatment for disease. While the precise mechanisms by which probiotics may inhibit disease have long been unknown, it appears that a genetically tweaked version of a common probiotic found in yogurt and cheese may offer an effective therapy for inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis. It may also prove to be useful in colon cancer, another disease triggered by inflammation.
Northwestern University researchers deleted a gene in the probiotic Lactobacillus acidophilus and fed the new form to mice with two different models of colitis. After 13 days of treatment, the novel probiotic strain nearly eliminated colon inflammation in the mice and halted progression of their disease by 95%.
“This opens brand new avenues to treat various autoimmune diseases of the gut, including inflammatory bowel disease and colon cancer, all which can be triggered by imbalanced inflammatory immune responses,” said Mansour Mohamadzadeh, Associate Professor of Medicine at Northwestern University Feinberg School of Medicine, member of the Robert H. Lurie Comprehensive Cancer Center of Northwestern University and lead investigator of the study.
In the study, the modified Lactobacillus acidophilus entered the gut, which is akin to a battlefield of friendly fire with immune cells attacking the intestine. The Lactobacillus acidophilus acted as the gut’s peacekeeping force, calming the overstimulated immune cells. The probiotic restored intestinal peace by mobilizing messenger immune cells, called dendritic cells. The dendritic cells, in turn, enhanced the production of other functional immune cells, regulatory T-cells that rebalanced intestinal and systemic inflammation.
“Such gene targeting in a probiotic bacteria such as Lactobacillus acidophilus offers the possibility of a safe, drug-free treatment in the near future,” Mohamadzadeh said. The next step will be a clinical trial with the new form of Lactobacillus acidophilus.
 Rafter J. The effects of probiotics on colon cancer development. Nutrition Research Reviews(2004), 17, 277?284
 Mohamadzadeh M, Pfeiler EA, Brown JB, Zadeh M, Gramarossa M, Managlia E, et al. Microbes and Health Sackler Colloquium: Regulation of induced colonic inflammation by Lactobacillus acidophilus deficient in lipoteichoic acid. Proc Natl Acad Sci U S A. 2011 Jan 31. [Epub ahead of print]