Modulation of gut microbiota protects against viral respiratory tract infections: a systematic review of animal and clinical studies.

2021-04-14
European journal of nutrition 60(8)
- Hai Yun Shi
- Xi Zhu
- Wei Lin Li
- Joyce W Y Mak
- Sunny H Wong
- Sheng Tao Zhu
- Shui Long Guo
- Francis K L Chan
- Shu Tian Zhang
- Siew C Ng

PubMed: 33852069
DOI: 10.1007/s00394-021-02519-x

Study Design

Type: Systematic Review
Sample size: n = 726
Population: 58 studies (9 randomized controlled trials; 49 animal studies)
Methods: systematic review of articles published in Embase and MEDLINE through 20 April 2020

Rigorous Journal

Background

Earlier studies suggest that probiotics have protective effects in the prevention of respiratory tract infections (RTIs). Whether such benefits apply to RTIs of viral origin and mechanisms supporting the effect remain unclear.

Aim

To determine the role of gut microbiota modulation on clinical and laboratory outcomes of viral RTIs.

Methods

We conducted a systematic review of articles published in Embase and MEDLINE through 20 April 2020 to identify studies reporting the effect of gut microbiota modulation on viral RTIs in clinical studies and animal models. The incidence of viral RTIs, clinical manifestations, viral load and immunological outcomes was evaluated.

Results

We included 58 studies (9 randomized controlled trials; 49 animal studies). Six of eight clinical trials consisting of 726 patients showed that probiotics administration was associated with a reduced risk of viral RTIs. Most commonly used probiotics were Lactobacillus followed by Bifidobacterium and Lactococcus. In animal models, treatment with probiotics before viral challenge had beneficial effects against influenza virus infection by improving infection-induced survival (20/22 studies), mitigating symptoms (21/21 studies) and decreasing viral load (23/25 studies). Probiotics and commensal gut microbiota exerted their beneficial effects through strengthening host immunity.

Conclusion

Modulation of gut microbiota represents a promising approach against viral RTIs via host innate and adaptive immunity regulation. Further research should focus on next generation probiotics specific to viral types in prevention and treatment of emerging viral RTIs.