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Taking probiotics can be good for you … but does not prevent childhood asthma: Study

December 17, 2013 — 

A large international study analyzing health benefits of probiotics on babies in utero or up to 12 months old, led by researchers Meghan Azad from the University of Alberta and the U of M’s Ryan Zarychanski, was published this month in the prestigious British Medical Journal.

Their team reviewed data from 20 clinical trials in Europe, Australia, New Zealand and Taiwan involving more than 4,800 children whose mothers either received probiotics (live ‘beneficial’ bacteria) during pregnancy or gave probiotics to their babies in the first year. The rate of doctor-diagnosed asthma was 11.2 per cent among infants who received probiotics and 10.2 per cent among babies who received the placebo.

“Taking probiotics had no effect on the asthma rate,” said Azad. “They can’t be recommended to prevent asthma, given the current evidence.”

She was quick to point out that probiotics remain useful for other purposes. “Other studies have shown that probiotics offer health benefits to infants who are born preterm and suffer from certain bowel conditions. There’s also evidence that probiotics might prevent eczema.”

The study was conducted as part of a new course offered jointly by the U of M and the George and Fay Yee Centre for Healthcare Innovation (CHI).  The course employs a unique format where each student assembles a research team and conducts a systematic review of a pressing health topic.

“The final assignment is not an exam, but a scientific paper that can be published in a top medical journal,” said Zarychanski, assistant professor of internal medicine at the Faculty of Medicine and clinician-scientist at CancerCare Manitoba, who developed the course to train upcoming Manitoba scientists in a method of research called ‘meta-analysis’.

“The course teaches students to summarize and analyze data from multiple studies conducted in all parts of the world, so that doctors can make clinical decisions based on all of the available evidence – not just the latest or biggest study,” said the critical care physician.

“One of our goals at CHI is ensuring that service providers integrate the latest research into their work to improve care for patients. This innovative course and the research produced by it have far reaching impacts. They positively change care for patients in Manitoba and in the wider sphere,” says Terry Klassen, academic director of CHI.

Azad was visiting research colleagues at the U of M when she saw the course advertised.  “I wanted to learn meta-analysis but never had the opportunity in Alberta, so I jumped at the chance.”  Her primary research involves studying infant gut bacteria to understand the recent epidemic of childhood allergies and asthma.  “We’ve learned that gut bacteria help train the immune system, and that asthmatic children have different gut bacteria than healthy children,” she explains.  “So I wanted to know whether probiotics might be useful in asthma prevention.”

As it turns out, the answer is “no” – or at least, “not yet.”

The study shows that at present there is no clinical evidence to support the use of probiotics for asthma prevention. But, Azad noted, the strategy may still have potential. The clinical trials she reviewed varied widely in the type, dose and duration of probiotic supplementation (among 20 trials, over 15 different probiotic strains were tested with a 1000-fold range in dose and a 24 month range in duration).

Furthermore, she said that most trials were not originally designed to detect asthma, so they did not always follow the children long enough to accurately diagnose this condition. “These issues should be addressed with extended follow-up of existing studies, and with new basic research and clinical trials,” she said.

Zarychanski expects that more research will be published from the CHI course: several other students have submitted their studies for publication, and a new class is set to begin in January.  This type of research is a key priority for the CHI, a joint University of Manitoba and Winnipeg Regional Health Authority initiative.

Azad is being recruited to continue her research in Manitoba, and is set to join the University of Manitoba and CHI as an assistant professor in 2014.


For more information contact Ilana Simon, Director of Communications & Marketing, Faculty of Medicine, University of Manitoba, 204-789-3427, (cell) 204-295-6777 or


Founded in 1883 as Western Canada’s first medical school, the University of Manitoba Faculty of Medicine has graduated more than 7,000 physicians who have become influential medical leaders, world renowned health researchers and dedicated doctors. As Manitoba’s only medical school, the U of M Faculty of Medicine has educated and trained the majority of our province’s physicians.



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