Probiotics and Seasonal Allergies

In the last couple years, it seems probiotics and supplements are discussed everywhere, from talk shows to the Target pharmacy aisle.

Now a Vanderbilt University study that reviewed 23 clinical trials concluded using probiotics may help alleviate the symptoms of allergic rhinitis (AR), also known as seasonal or perennial allergies.

The results were published in April in the online version of the journal International Forum of Allergy & Rhinology. “When you look at all the studies combined, there was a statistically significant improvement in both the rhinitis-specific quality of life of those patients and in their nasal specific quality of life,” said lead author Justin Turner, MD, PhD, assistant professor of otolaryngology at Vanderbilt University Bill Wilkerson Center. But he cautioned that “the jury is still out” and suggests the topic is ripe for future studies.

The Science of Supplements

Probiotics are microorganisms that are thought to have gastrointestinal benefits when consumed. In the last 20 years, doctors have been suggesting probiotics to patient from mild digestive problems to the superbug c. diff. More recently, probiotics have been proven to help eczema and are likely to be effective for IBS.

Probiotics are present in some foods, such as yogurt or even chocolate, or can be taken as a dietary supplement. But comprehensive data about their effectiveness is more difficult to come by because they are regulated as a supplement and not as a drug, Turner said.

The study, which included Alexander Zajac, MD, resident in general surgery and, Austin Adams, MD, a resident in otolaryngology-head and neck surgery, “represents the most comprehensive analysis to date on the use of probiotics for the treatment of AR”.

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“It was a systematic review where basically we just searched the medical literature for all studies that have evaluated treatment of allergic rhinitis with probiotics,” Turner said. “There was a lot of variability in the individual studies, but a majority of the studies did show at least some benefit with the use of probiotics compared to placebo.”

Of the 23 studies that were reviewed, 17 showed that probiotics were linked to improvement in at least one facet of a patient’s health – either rhinitis-specific quality of life or in symptoms. A total of 1,919 patients were involved.

“That means that six (studies) did not show any benefit at all, so it’s hard to make any firm conclusions about that,” Turner said. “We also found that the studies were very variable, so they used a lot of different bacterial strains and treatment durations.”

Turner noted that probiotics were not associated with any adverse patient outcomes. Out of 2,000 participants, only one left the study for symptoms. Some participants complained of diarrhea, abdominal pain and flatulence but the number of grievances was the same as in the control group. According to Turner, none of the patients in either group required any treatment or intervention.

Hygiene Hypothesis

While the medical community still doesn’t know the exact reason probiotics are associated with symptom improvement, Turner remarked that the majority of studies show a benefit.

Lynn Miller, BSN, RN, Baker Allergy, Asthma & Dermatology in Lake Oswego, Ore. and member of the American Society of Allergy Nurses, believes the evidence supporting probiotics to improve eczema or even allergies may be an expansion of the hygiene hypothesis.

“Basically, allergies are on the rise because we’re too hygienic,” she explained. “Cultures with parasites and where kids are exposed to normal pathogens have normal allergy rates. That’s where probiotics come into play. “

She concluded that probiotics may be most useful during the infancy stage because adults have already been sensitized.

Turner agreed that the hygiene hypothesis is relevant and the lack of exposure to bacteria may be the culprit behind higher rates of autoimmune and inflammatory diseases.

“Americans spend more time indoors now than ever before,” he added. “In the 50s, people spent 50% of their time inside. Now it’s 90% of our time that’s spent inside.”

His review found equal benefits for using probiotics to treat hay fever in both pediatric and adult populations, though he didn’t study newborns or expectant mothers.

Future Study Considerations

Turner hopes his study is a stepping stone for future research on probiotics for hay fever.

He’d also be interested in learning more about the most effective dose or form of probiotics.

“All of the studies utilized supplements with a single bacterial supplements,” Turner commented. “The majority of studies, 16 out of 23, refer to Lactobacillus but there’s still not enough power to say which is better. I don’t think any of the studies just looked at eating yogurt with probiotics.”

Turner cautioned that probiotics are not a substitute for current medications used to treat symptoms.

“This is not by any means suggesting that this is a cure for allergies,” he said, but suggests telling patients that supplements or yogurt cultures potentially provide some benefits with symptoms during the allergy season.

Robin Hocevar is on staff at ADVANCE. Contact [email protected].

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