In an animal study performed by scientists in Japan, the normal bowel bacteria, Lactobacillus casei seemed to have a protective effect against the flu. In the study, published in the journal Clinical and Diagnostic Laboratory Immunology (May 2001; 8:593-597), mice were inoculated with flu virus. One group of mice was given Lactobacillus casei in a nasal spray three days prior to the inoculation. The group treated with the bacteria had a 90% lower viral load than mice who were not treated. Also, 69% of the mice given the bacteria survived the flu, compared to 15% of the mice who were not given the bacteria.