In a study published in the British Journal of Nutrition, researchers found that supplementing with bifidobacteria probiotics will reduce colds and flu. The study followed 581 college students for six weeks as they prepared for their final exams. During the study period, the students consumed a placebo or a daily supplement with one of three probiotics, including Bifidobacterium bifidum.

The students given the bifidum supplement experienced significantly fewer cold or flu infections, and when they did succumb, the infection was generally less severe. The other probiotic supplements did not reduce colds or flu compared to the placebo for the six weeks.