The World Health Organization defines probiotics as “live microorganisms, which when administered in adequate amounts confer a health benefit on the host.” The most common types of these beneficial bacteria are Lactobacilli and Bifidobacteria. Previous studies indicate that probiotics may have a role in treating gastrointestinal illnesses, boosting immunity, and preventing or slowing the development of certain types of cancer. In two recent NCCAM-funded studies, researchers investigated how probiotics may promote such health benefits.
Researchers at Baylor College of Medicine and M.D. Anderson Cancer Center investigated how Lactobacillus reuteri ATCC PTA 6475 might work to slow the growth of certain cancerous tumors. Their study documented the molecular mechanisms of the probiotic's effects in human myeloid leukemia-derived cells—i.e., how it regulates the proliferation of cancer cells and promotes cancer cell death. The researchers noted that a better understanding of these effects may lead to development of probiotic-based regimens for preventing colorectal cancer and inflammatory bowel disease.
In another study, researchers at Virginia Polytechnic Institute and Ohio State University looked at whether Lactobacillus acidophilus might enhance the immune-potentiating effects of an attenuated vaccine (a vaccine prepared from a weakened live virus) against human rotavirus infection—the most common cause of severe dehydrating diarrhea in infants and children worldwide. The investigators' tests on newborn pigs found that animals given both a vaccine and the probiotic had a better immune response than the animals given the vaccine alone. The researchers concluded that probiotics may offer a safe way to increase the effectiveness of rotavirus vaccine in humans.
In both studies, the investigators called for additional research into the mechanisms behind the health-related effects of probiotics.
Iyer C, Kosters A, Sethi G, et al.. Probiotic Lactobacillus reuteri promotes TNF-induced apoptosis in human myeloid leukemia-derived cells by modulation of NF-kB and MAPK signaling.. Cellular Microbiology..;10(7):1442–1452..2008
Zhang W, Azevedo MSP, Wen K, et al. Probiotic Lactobacillus acidophilus enhances the immunogenicity of an oral rotavirus vaccine in gnotobiotic pigs. Vaccine.;26(29–30):3655–3661.2008