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Research Article

Effect of fermented milk on upper respiratory tract infection in adults who lived in the haze area of Northern China: a randomized clinical trial

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Pages 645-650 | Received 17 Dec 2020, Accepted 09 May 2021, Published online: 01 Jun 2021
 

Abstract

Context

Upper respiratory tract infection (URTI) is the most common illness in humans. Fermented milk containing probiotics can mitigate URTI symptoms.

Objective

This study tests the effect of fermented milk (Qingrun), a yogurt supplemented with Bifidobacterium animalis subsp. lactis Bl-04, on adults with URTIs who live in a haze-covered area in a randomized clinical trial.

Materials and methods

A total of 136 subjects were enrolled in the study at the baseline and randomized to consume either control yogurt or Qingrun yogurt (250 g) once daily for 12 weeks. The duration and severity of URTI were evaluated by the Wisconsin Upper Respiratory Symptom Survey–24. Blood and faecal samples were collected at the baseline and post-intervention, to determine the changes of immune biomarkers.

Results

Qingrun yogurt significantly reduced the incidence of the common cold (OR, 0.38; 95% CI, 0.17–0.81; p = 0.013) and influenza-like illness (OR, 0.32; 95% CI, 0.11–0.97; p = 0.045). Compared to the control yogurt, Qingrun yogurt significantly reduced the duration (1.23 ± 2.73 vs. 4.78 ± 5.09 d) and severity score (3.58 ± 7.12 vs. 11.37 ± 11.73) of URTI. In addition, the post-intervention levels of interferon-γ (139.49 ± 59.49 vs. 113.45 ± 65.12 pg/mL) and secretory immunoglobulin A (529.19 ± 91.70 vs. 388.88 ± 53.83 mg/dL) significantly increased in the Qingrun group, compared with those in the control group.

Conclusions

Qingrun yogurt showed a protective effect against URTI in adults, suggesting that the use of yogurt with probiotics could be a promising dietary supplement for mitigating URTI.

Acknowledgement

We thank Dr. Li Zhang from SPRIM China for his team’s work in coordinating the clinical trial.

Disclosure statement

No potential conflict of interest was reported by the author(s).