A large, placebo-controlled trial found that Bifidobacterium bifidum, a type of probiotic bacteria, helped reduce the incidence of colds or the flu in college students. Published in the British Journal of Nutrition, the study involved 581 students. Each received a placebo, or a probiotic supplement containing one of three probiotic strains (Lactobacillus helveticus, Bifidobacterium longum ssp. infantis, or Bifidobacterium bifidum), daily for six weeks. The experiment took place during fall semester finals, a time when students are particularly stressed and researchers could expect that some of them would contract a cold or the flu. Here’s what the researchers discovered:

• The percentage of students reporting a day or more of cold or flu symptoms was significantly lower in the Bifidobacterium bifidum group than in the placebo group. The other two probiotic strains did not lower the incidence of colds or the flu compared to the placebo.
• However, after adjusting for stress levels and hours of sleep, the proportion of students reporting a cold or the flu on any given day was lower in both the Bifidobacterium bifidum and Bifidobacterium longum ssp. infantis groups at weeks two and three compared to the placebo.

This research adds to the growing body of evidence showing that probiotics may help prevent or reduce the duration of some infections.

Source: British Journal of Nutrition