But study author Leyer said that the reason previous studies may not have shown dramatic effects from probiotic use was because they measured biomarkers such as the activity of immune cells compared to the clinical outcome measurements such as incidence, duration and absenteeism from school that he measured.
While European and Asian countries have been incorporating probiotics into foods and products for treatment regimes for many years, the practice has just begun to gain awareness in the United States, most notably with the introduction of various probiotic yogurts that tout health benefits.
"As information about this study gets out, that subset of parents who are very much into natural things will take heart from this," said Dr. William Schaffner, chairman of Preventive Medicine at Vanderbilt Medical Center in Nashville, Tenn. "[The regime] requires sustained supplementation. You have to stick with the program and it's twice a day. But I think there are some families who would do it and there would be few adverse effects."
In addition, Schaffner said that probiotics or any other kind of supplement that purports to prevent cold and flu should not be used as a substitute for flu vaccines. Rather, they should be seen as an additional program.
Bhatia of the Atlanta Center for Holistic and Integrative Medicine said she would like to see more rigorous, large-scale studies that confirm Leyer's results done in the United States, but that the caveats did not discount the results and recommendations of the study.
"There is a push by patients and by consumers to learn more about preventive or wellness approach to medicine," she said. "Poor gut health makes you more likely to catch a virus or have a chronic illness."