So, What's The Deal with Probiotics and Asthma?
Back in October 2016, I unpacked the mysteries of prebiotics as they pertain to some recent exercise-inducedasthma research—to understand prebiotics, I had to unravel some stuff about probiotics as well, and why they are different. But just to confuse us all, in the file of Other Claims the Internet Makes, apparently probiotics (like, the life-bacterial-culture-in-yogurt-and-yogurt-ads kind) are the best thing since sliced bread. (…And seriously, who actually likes slicing bread? Not me.)
A Refresher on Probiotics
Probiotics are good bacteria that occasionally get thrown out of whack, usually in the gastrointestinal system. Often this imbalance is caused by taking antibiotics for an infection (one reason doctors may recommend probiotics is to take with a course of antibiotics to reduce GI side effects). There is some (read: a little) evidence suggesting that these very same probiotics may be good for asthma. Pause. Stop. Hold on for a second before you hit up Google, okay? The claims that probiotics will be a home remedy or cure for asthma are completely incorrect. This is new-ish and very incomplete research.
By rebalancing the gut ecosystem using probiotics (which are known for their digestive benefits), this may have an influence on the brain and respiratory systems.1
Not clearly understood: What we know about probiotics so far
- Evidence—so far—does NOT support probiotics as an effective method to prevent OR treat asthma.2
- The São Paulo Research Foundation of the University of São Paulo produced research in 2013 that Bifdobacterium longum (a common probiotic), when administered to mice reduced the amount of mucus in the lungs of mice, a decrease in inflammatory blood markers associated with respiratory disease, and decreased in airway hyperreactivity1, which we know is the cause of asthma symptoms.
- In a Canadian study, infants who experienced allergic reactions and wheezing at one year of age, had lower amounts of certain bacteria in their feces at three months of age than children who had less atopic tendency at age 1.3 This is notable, since probiotics are, remember, bacteria that have been considered to keep the gastrointestinal system functioning properly. It is noted that the bacterial changes in stool samples were no longer present at one year of age.3
- A 2008 meta-analysis of all research available at the time regarding randomized control trials for asthma and/or allergic rhinitis and probiotic treatment states “The exact mechanism of action of probiotics is not clearly understood.”4 In 2017, this still appears to be the case! For allergic rhinitis, the 2008 meta-analysis showed reduced symptom scores and medication use, however, asthma had no reported improvements from probiotic treatment.4
- The link between probiotics use and asthma may have links to the hygiene hypothesis, in which bacteria is beneficial to building a strong immune system and decreasing sensitivity to environmental stimuli—such as asthma triggers.5
What we have to learn
Most of the studies I looked at noted that more research needs to be done.4 Here are some specific points that are considered to require more research before we know the validity of whether probiotics are helpful for asthma and allergies.
- In reference to the Brazilian (São Paulo) study, because there was significant reduction in biomarkers such as eosinophils, and airway hyperreactivity, researchers now must consider whether simply the introduction of the probiotic Bifdobacterium longum to mice (…and hopefully in the future, humans!) in itself reduces asthma symptoms, or if the improvement is caused by another reaction that goes on after probiotics are metabolized (processed) by the body.1
- Regarding the Canadian study, of the 22 of 319 children who presented with bacterial anomalies at 3 months, 19 of those children were considered at high risk of developing asthma or were diagnosed with asthma by the time they were three years old.3 The article considers the small sample size as being a limiting factor, and needing larger studies to determine the predictive nature of these results, and concluded further research needs to be done to determine the potential efficacy of introducing positive bacteria (probiotics) to children who are at risk of asthma or allergies.3
- “Very low-quality evidence” means that international guidelines and recommendations organizations require more large studies to be completed, notes a 2016 meta-analysis of probiotics for asthma5 The links are so far stronger for treating allergic rhinitis and eczema, but not asthma.3,4,5
For the time being, the evidence simply is not there. It is probably reasonable to stick with the National Health Service’s recommendation to not go out and buy a year supply of yogurt3 (I mean, despite its deliciousness, it does go bad!). If you decide you are interested in trying a probiotic still, speak with your doctor to ensure you aren’t at risk to have a negative reaction (as some types of immune-suppressing treatments can result in illness if taking probiotic supplements) and get their advice regarding this addition to your routine.
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