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

Figures & data

Figure 1. Flowchart of the clinical trial.

Table 1. Baseline characteristics.

	Control yogurt n = 61	Qingrun yogurt n = 62	p-value
Male	35 (57.4%)	34 (54.8%)	0.777
Age (years)	35.7 ± 7.6	37.2 ± 9.2	0.310
Weight (kg)	68.8 ± 14.3	67.1 ± 12.2	0.479
Height (cm)	168.5 ± 8.3	166.8 ± 7.7	0.228
BMI (kg/m^2)	24.0 ± 3.3	24.0 ± 3.0	0.946
Body temperature (°C)	36.3 ± 0.3	36.3 ± 0.2	0.458
Systolic blood pressure (mmHg)	112.9 ± 9.8	115.8 ± 8.2	0.081
Diastolic blood pressure (mmHg)	73.6 ± 6.3	75.5 ± 6.2	0.095
Number of URTI episodes in the past one year
4 times	19 (31.2%)	14 (22.7%)	0.344
5 times	32 (52.5%)	32 (51.6%)
6 times	10 (16.4%)	16 (25.8%)
History of smoking	20 (32.8%)	22 (35.5%)	0.753
History of drinking	6 (9.8%)	6 (9.7%)	0.976

Data are presented as mean ± standard deviation or frequency (percentage).

Group deference was evaluated by using chi-squared test or analysis of variance (ANOVA).

URTI: upper respiratory tract infection.

Table 2. Incidence of upper respiratory tract infection throughout the study.

	Control yogurt n = 61	Qingrun yogurt n = 62	OR (95% CI)	p-value
Incidence of common cold	28 (45.9%)	15 (24.2%)	0.38 (0.17, 0.81)	0.013
Incidence of influenza-like illness	13 (21.3%)	5 (8.1%)	0.32 (0.11, 0.97)	0.045

Data are presented as frequency (percentage).

Group deference was evaluated by using logistic regression.

OR: odd ratios; CI: confidence interval.

Table 3. Frequency distribution of upper respiratory tract infection (URTI) throughout the study.

Number of URTI episodes	Overall			Smoker			Non-smoker			Smoker vs. Non-smoker p-value
	Control yogurt n = 61	Qingrun yogurt n = 62	p-value	Control yogurt n = 20	Qingrun yogurt n = 22	p-value	Control yogurt n = 41	Qingrun yogurt n = 40	p-value
None	20 (32.8%)	42 (67.7%)	0.0002	1 (5.0%)	11 (50.0%)	0.003	19 (46.3%)	31 (77.5%)	0.006	0.0001
Once	35 (57.4%)	17 (27.4%)		14 (70.0%)	9 (40.9%)		21 (51.2%)	8 (20.0%)
Twice	6 (9.8%)	3 (4.8%)		5 (25.0%)	2 (9.1%)		1 (2.4%)	1 (2.5%)

Data are presented as frequency (percentage).

Group deference was evaluated by using Kruskal–Wallis test.

Table 4. Duration and severity of upper respiratory tract infection (URTI) symptoms throughout the study.

	Overall			Smoker			Non-smoker			Smoker vs. non-smoker p-value
	Control yogurt n = 61	Qingrun yogurt n = 62	p-value	Control yogurt n = 20	Qingrun yogurt n = 22	p-value	Control yogurt n = 41	Qingrun yogurt n = 40	p-value
Duration of URTI symptoms (days)	6.16 ± 5.46 7 (0–23)	1.95 ± 3.39 0 (0–13)	<0.0001	9.00 ± 5.21 9 (0–23)	3.27 ± 4.08 1 (0–13)	0.0005	4.78 ± 5.09 5 (0–16)	1.23 ± 2.73 0 (0–11)	0.0008	0.0009
Severity score of URTI symptoms	14.90 ± 12.25 18 (0–38)	5.79 ± 9.03 0 (0–27)	<0.0001	22.15 ± 10.10 20 (0–38)	9.82 ± 10.78 5 (0–27)	0.002	11.37 ± 11.73 9 (0–38)	3.58 ± 7.12 0 (0–24)	0.0009	0.0003
Duration of medication due to URTI (days)	3.64 ± 3.99 2 (0–14)	0.72 ± 1.79 0 (0–8)	<0.0001	5.70 ± 3.77 6 (0–14)	1.09 ± 2.18 0 (0–8)	<0.0001	2.63 ± 3.74 0 (0–13)	0.53 ± 1.54 0 (0–7)	0.003	0.0008
Duration of sick leave due to URTI (days)	0.52 ± 1.79 0 (0–10)	0.13 ± 0.59 0 (0–4)	0.433	0.90 ± 2.47 0 (0–10)	0.27 ± 0.94 0 (0–4)	0.502	0.34 ± 1.35 0 (0-–7)	0.05 ± 0.22 0 (0–1)	0.618	0.253

Data are presented as mean ± standard deviation and median (min-max).

Group deference was evaluated by using Kruskal–Wallis test.

Table 5. Changes in the immune biomarkers.

	Biomarkers	Control yogurt n = 61	Qingrun yogurt n = 62	p-value
Baseline	Interleukin 4, IL-4 (ng/ml)	0.88 ± 0.29	0.87 ± 0.29	0.850
	Interleukin 8, IL-8 (pg/ml)	29.49 ± 16.05	29.97 ± 18.03	0.877
	Interleukin 10, IL-10 (pg/ml)	23.18 ± 1.43	23.06 ± 1.13	0.621
	Interferon γ, IFN-γ (pg/ml)	112.33 ± 59.95	114.49 ± 56.23	0.838
	Immunoglobulin A, IgA (g/L)	2.24 ± 0.53	2.35 ± 0.71	0.374
	Immunoglobulin G, IgG (g/L)	11.61 ± 2.26	11.65 ± 2.45	0.925
	Immunoglobulin M, IgM (g/L)	1.10 ± 0.42	1.13 ± 0.44	0.709
	Secretory IgA, SIgA (mg/dL)	384.27 ± 58.60	385.03 ± 23.93	0.952
Post-intervention	Interleukin 4, IL-4 (ng/ml)	0.85 ± 0.27	0.85 ± 0.27	0.947
	Interleukin 8, IL-8 (pg/ml)	27.78 ± 15.96	26.12 ± 15.66	0.561
	Interleukin 10, IL-10 (pg/ml)	22.77 ± 1.13	22.78 ± 0.96	0.935
	Interferon γ, IFN-γ (pg/ml)	113.45 ± 65.12	139.49 ± 59.49	0.028
	Immunoglobulin A, IgA (g/L)	2.26 ± 0.69	2.37 ± 0.74	0.401
	Immunoglobulin G, IgG (g/L)	11.66 ± 2.39	12.07 ± 2.29	0.338
	Immunoglobulin M, IgM (g/L)	1.11 ± 0.41	1.14 ± 0.48	0.780
	Secretory IgA, SIgA (mg/dL)	388.88 ± 53.83	529.19 ± 91.70	<0.0001

Data are presented as mean ± standard deviation.

Group deference was evaluated by using analysis of variance (ANOVA).