Table 2.

Descriptive Table of the Biases of the Included Randomized Clinical Trials.

Study	Question Focus	Allocation Blinding	Double- Blind	Losses (>20%)	Prognostic or Demographic Characteristics	Outcomes	Intention to Treat Analysis	Sample Calculation	Adequate Follow-Up
use of probiotics
[124]	Yes	No	No	No	Yes	Yes	Yes	No	Yes
[125]	Yes	Yes	Yes	No	No	Yes	Yes	No	Yes
[126]	Yes	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes
[127]	Yes	No	No	Yes	No	Yes	Yes	Yes	Yes
[128]	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
[129]	Yes	Yes	Yes	Yes	Yes	Yes	Yes	NR	No
use of prebiotics
[130]	Yes	Yes	Yes	No	Yes	Yes	Yes	No	Yes
[131]	Yes	Yes	Yes	No	Yes	Yes	Yes	No	Yes
[132]	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
use of synbiotics
[136]	Yes	No	No	No	Yes	Yes	Yes	Yes	Yes
[133]	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
[134]	Yes	Yes	Yes	Yes	Yes	Yes	Yes	NR	Yes
[135]	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes

NR: not reported.