Table 1. Office of Health Assessment and Translation tool for risk of bias and methodological quality assessment.

++: definitely low risk of bias; +: probably low risk of bias; -: probably high risk of bias; NR: insufficient information; --: definitely high risk of bias

Vitro studies	Selection bias		Performance bias		Attrition/exclusion bias	Detection bias		Selective reporting bias	Other sources of bias
Study, country	1. Was random allocation present?	2. Was allocation to study groups adequately concealed?	5. Were the experimental conditions identical across study groups?	6. Were the research personnel blinded to the study group?	7. Were outcome data complete without attrition or exclusion from analysis?	8. Can we be confident in the intervention characterization?	9. Can we be confident in the outcome assessment?	10. Were all measured outcomes reported?	11. Statistical methods appropriate or did researchers adhere to the study protocol?
Patil et al. [11], India	NR	++	++	NR	++	++	_	++	+
Ghasemi et al. [16], Iran	NR	+	++	_	+	+	_ _	++	++
Eskandarinezhad et al. [17], Iran	_	+	+	NR	++	+	_ _	+	+
Varshini et al. [18], India	NR	++	+	NR	++	++	_	+	++
Bhardwaj et al. [15], India	NR	+	++	_	+	+	_ _	++	++
Ismail et al. [19], Malaysia	_	+	_	NR	++	++	_	++	++
Abbaszadegan et al. [3], Iran	NR	++	+	NR	++	++	_ _	+	+