Probiotics: Powerful Prevention?

What if there were a simple way that you could drop the number of coughs, colds, and fevers your child gets this school year by more than half? And when your child does get sick, what if you could cut the length of the illness in half? What if you could slash the odds that your child will need antibiotics this year, while decreasing missed school days?

Researchers randomly assigned 326 preschool children to one of three groups. In each group, the caregivers were given little foil packets of dry powder that were mixed into 4 ounces of milk for the children to drink twice a day for 6 months. During the week, the milk was prepared and served at school; on the weekends the parents were in charge.

For one group the powder contained 10 billion CFUs of Lactobacillus acidophilus, a type of probiotic or beneficial bacteria (by comparison, a typical serving of yogurt might contain 1 billion CFUs). For the second group the powder likewise contained a total of 10 billion CFUs of probiotics – but it was a mixture of two strains (Lactobacillus acidophilus and Bifidobacterium animalis). Probiotic supplements like this are available in many health, food, or drug stores. For the third group the powder was nothing but an inert placebo.

The school year was quite different for the three groups! In the placebo group, most of the kids got a fever sometime in the next 6 months, much as one would expect. But, the number of kids with fever was slashed by more than half among those who got the single probiotic in their mystery packets — and by almost three quarters among those who received the double probiotic —even though the kids were in the same preschool classes. Similar dramatic reductions were seen in coughs, runny noses, antibiotic use, duration of illness, and missed school days.

What we think of as “our” bodies includes ten times as many bacterial cells as human cells. Promoting healthy, diverse gut bacteria appears able to make a big difference in keeping us healthy.

Six Month Experience

Placebo Single Probiotic Mixed Probiotics
Kids with fever66%31%18%
Kids with cough87%51%33%
Kids with a runny nose85%61%35%
Kids treated with an antibiotic57%18%9%
Average length of illness, when sick6.5 days4.5 days3.4 days


Bottom line: When families didn’t do anything, most kids developed fever, cough, runny nose, and were treated with antibiotics sometime in the next 6 months. But among those who were given the probiotics, most kids did not get a fever, cough, runny nose or antibiotics over the next 6 months. And if they did get sick, it lasted on average about half as long. A dramatic difference!

Leyer GJ et al. Probiotic effects on cold and influenza-like symptom incidence and duration in children. Pediatrics 2009 Aug; 124:e172.

Last medical review on: December 14, 2017
About the Author
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Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.
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Recent Comments

This is fascinating! I definitely want to start my daughter on these probiotics but am having trouble finding a product with those specific probiotics. Any advice? Also, is it safe to give on an ongoing basis or just for a 6 month or so stint at a time?