Evidence of the health benefits of lactobacillus and other probiotics – also known as "friendly bacteria" – is impressive. Many studies have investigated the role of various strains of bacteria in preventing and treating such illnesses as inflammatory bowel disease, urinary tract infections, diarrhea, and even colon cancer. Last year the American Journal of Gastroenterology published an entire supplemental issue dedicated to the use of probiotics in disease treatment. (1)
A recent study on the prevention of gastrointestinal infections suggests that probiotics may also be effective against viral infections. In this study, a group of 81 children was randomized to receive either a strain of lactobacillus (Lactobacillus GG) or "placebo" after hospital admission. Because many infections are acquired in the hospital (termed nosocomial infections), the researchers decided to test the protective effects of probiotics in this setting.
Of the 81 children in the study, 15 (18.5 percent) experienced diarrhea during their hospitalization. Stool analysis revealed that rotavirus was the most common cause. Probiotic supplement use was associated with a significantly reduced risk of diarrhea. Only three of the children (6.7 percent) in the group which had been given probiotics got diarrhea, whereas 12 children (33.3 percent) in the "placebo group" experienced diarrhea during their hospital stay. (2) The prevalence of rotavirus infection was similar in both groups, but the number of children with symptoms was dramatically lower in the probiotic group. So, although all these infants were exposed to the virus in hospital, the group given the lactobacillus supplement were able to resist succumbing to the infection!
Probiotics appear to work through a variety of mechanisms, from decreasing pathogen adherence to the intestinal wall to stimulating the systemic immune response. And they seem to be a safe, effective way to prevent virally induced gastrointestinal infections.
1. Am J Gastroenterol 2000 (Jan); 95 (1 Suppl): S1–25
2. Szajewska H, et al.
Efficacy of Lactobacillus GG in Prevention of Nosocomial Diarrhea in Infants
J Pediatr 2001 (Mar); 138 (3): 361–365