Probiotics, or "good bacteria," may be helpful to people with seasonal allergies, a new review suggests.
Researchers analyzed the results from more than 20 previous studies and found that hay fever sufferers may get some benefits from using probiotics, improving their symptoms and quality of life.
But the jury is still out about whether probiotics are actually an effective treatment for people with seasonal allergies, said lead author Dr. Justin Turner, an ear-nose-and-throat surgeon at Vanderbilt University Medical Center in Nashville, Tennessee.
Additional high-quality studies are needed before doctors would recommend for or against using probiotics to help treat people with seasonal allergies, Turner said.
Probiotics are bacteria that are thought to help maintain a healthy gut. They are found in certain foods, such as yogurt with live active cultures, kefir and sauerkraut, and also supplements. Probiotics may change the balance of bacteria in the intestines in a way that could protect the immune system from flaring up in response to pollens and other allergens, which may help reduce allergy symptoms, Turner said. [9 Myths About Seasonal Allergies]
But he also cautioned that there is still much more information that needs to be understood about the effect of probiotics on the immune system.
Unanswered questions
Seasonal allergies are estimated to affect approximately 50 million Americans, according to the American College of Allergy, Asthma and Immunology. Allergy symptoms such as sneezing, a stuffy or runny nose, and itchy and watery eyes are typically treated with a combination of medications, including antihistamines, decongestants and steroid nasal sprays.
In the new study, published online in April in the journal International Forum of Allergy & Rhinology, researchers reviewed data from 23 randomized trials and more than 1,900 people.
They found that the majority of these studies (17 of 23) showed that people with seasonal allergies who took probiotic supplements or ate foods containing probiotics showed improvement in at least one outcome measure, such as improving their allergy symptoms, or their general quality of life, compared with allergy sufferers who took a placebo.
Six of 23 studies found probiotics had no benefit to people with hay fever, the researchers said.
But because the studies used different strains of live bacteria, different dosages and different probiotic supplement formulations over different periods of time, it is difficult to make any formal recommendations about probiotic use, bacterial strains or length of treatment that may benefit people with seasonal allergies, Turner said.
Even if probiotics prove effective for seasonal allergies, it's unlikely they would replace the standard medical treatments currently used by people affected by them, Turner said.
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