Probiotic Supplementation Improves Forced Expiratory Volume and Forced Vital Capacity in Subjects with Asthma

by | Mar 13, 2023 | 2023, Asthma, Probiotics

Written by Taylor Woosley, Staff Writer. 8-week once daily supplementation of a probiotic significantly increased FEV1 (p < 0.01) and FVC (p < 0.001), while also reducing the inflammation-related miRNAs of both miR-146 and miR-16 compared with baseline (p < 0.05). 

Asthma is one of the most common respiratory diseases that affects both children and adults worldwide, with diverse phenotypes and underlying pathogenetic mechanisms poorly understood1. It affects around 8.2% of the US population and over 300 million people worldwide2. Common symptoms include wheezing, coughing, chest tightness, and shortness of breath3. In most subjects with asthma a good disease control can be achieved using standard inhaled treatments, but around 5-10% of patients experience various subtypes of inadequately controlled and difficult-to-treat asthma4.

The gut microbiota possesses an important link with the development of the immune system and a dysregulation of the gut flora was in the asthmatic disease emergence5. Probiotics, live microorganisms that can confer a health benefit on the host, have shown anti-inflammatory effects and can regulate the gut-lung-axis through modulating gut microbial composition, enhancing microbial metabolite levels, and modulating host immunity6.

Sadrifar et al. conducted a double-blind, parallel placebo-controlled randomized clinical trial to investigate the effects of probiotic supplementation on clinical symptoms, changes in cytokines and microRNAs, and pulmonary function in patients with asthma. Subjects had a history of mild to moderate asthma for a minimum of 1 year, with a mean age of 38.62 ± 10.49. Inclusion criteria were based on the Global Initiative for Asthma (GINA) and consisted of having a history of 2 or more episodes of wheezing within the past 6 months and/ or a bronchodilator test confirming a positive response with a 12% increase in forced expiratory volume (FEV1) over 1 second. Participants (n=35) were randomly divided into probiotic (n=17) and placebo (n=18) groups and took part in the intervention for 60 days.

Blood samples were obtained from all participants before and 60 days after the intervention. At each visit, patients underwent a physical examination and had blood pressure, heart rate, and pulmonary functions measured, and had further evaluations of asthma symptoms, exacerbations, and adverse events. Those in the probiotic supplement group consumed one capsule a day after lunch containing seven natural strains of beneficial bacteria including Lactobacillus, Bifidobacterium, and Streptococcus strains, along with 28.5 mg fructo-oligosaccharide. The control group consumed one capsule a day containing 500 mg starch.

Primary outcome measures included asthma control test (ACT) scores, Forced Expiratory Volume in first second (FEV1), Forced Vital Capacity (FVC) and Forced Expiratory Volume in first second (FEV1)/ Forced Vital Capacity (FVC) ratio. Secondary outcome measures were changes in quality-of-life questionnaire scores (AQLQ), gene expression of miR-21, miR-155, miR-146a, miR-126, miR-16, and miR-133b in plasma, as well as IL-4 and IFN-γ plasma levels during the 60-day treatment. Data comparison between groups and within groups was analyzed using paired t-test, independent t-test, Wilcoxon, and Mann-Whitney tests. Significant findings of the study are as follows:

  • A significant decrease in IL-4 was observed following the administration of probiotic capsules compared to baseline (p < 0.05).
  • FEV1 and FVC in the probiotic group at the end of the intervention were significantly higher than at the beginning of the study (p < 0.01) and (p < 0.001), respectively. However, the results in the probiotic group were not significantly different compared to placebo group results.
  • Patients in the probiotic group significantly improved ACT (p < 0.001) and AQLQ (p < 0.0001) scores compared to baseline.

Results of the study show that 8-week intervention of a once daily probiotic capsule significantly improved ACT and AQLQ scores, while also improving lung function. Furthermore, probiotic use reduced inflammatory levels in subjects, suggesting that probiotics may be an effective short-term treatment for those with asthma. Study limitations include the small sample size and the lack of testing stool samples to check differences in bacterial counts and species between groups.

Source: Sadrifar, Sina, Tannaz Abbasi-Dokht, Sarvenaz Forouzandeh, Farhad Malek, Bahman Yousefi, Amir Salek Farrokhi, Jafar Karami, and Rasoul Baharlou. “Immunomodulatory effects of probiotic supplementation in patients with asthma: a randomized, double-blind, placebo-controlled trial.” Allergy, Asthma & Clinical Immunology 19, no. 1 (2023): 1-10.

© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. 

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Posted March 13, 2023.

Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.

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