Table 2 

The effect of probiotic treatment on the number, duration, severity and combined load of gastrointestinal symptoms 

Effect of probiotic treatment relative to placebo (mean; 99% CI) 



Probiotic group (mean ± SD) 
Placebo group (mean ± SD) 
Ratio 
Difference 
Qualitative inference 



Males 

Number of episodes 
1.01 ± 1.70 
0.49 ± 0.90 
2.06; 0.51 to 11 
Likely ↑ 

Duration (d) 
3.3 ± 5.8 
1.3 ± 7.7 
2.57: 0.53 to 17 
Likely ↑ 

Severity (13 scale) 
1.31 ± 0.33 
1.78 ± 0.73 
0.47; 1.21 to 0.28 
Possible ↓ 

Symptom Load (severitydays) 
4.4 ± 8.1 
2.5 ± 5.8 
1.76; 0.34 to 15 
Possible ↑ 

Females 

Number of episodes 
1.44 ± 1.71 
0.48 ± 0.71 
3.02; 0.76 to 17 
Likely ↑ 

Duration (d) 
3.9 ± 5.4 
2.1 ± 4.3 
1.85; 0.35 to 27 
Possible ↑ 

Severity (13 scale) 
1.44 ± 0.68 
1.75 ± 0.88 
0.31; 1.39 to 0.79 
Possible ↓ 

Symptom Load (severitydays) 
5.2 ± 7.08 
2.9 ± 5.1 
1.81; 0.37 to 24 
Possible ↑ 



SD, standard deviation; CI, confidence interval. Smallest clinically important values for assessing effects qualitatively: ratios, ×/÷1.20; differences, ± 0.5 

West et al. Nutrition Journal 2011 10:30 doi:10.1186/147528911030 