Table 1.

Risk of bias items for each included randomized control trial study

	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective outcome reporting	Other sources of bias
Bostock et al. [16]	+	+	?	+	?	?	+
Behrendt et al. [29]	+	+	–	+	–	–	?
Wolever et al. [30]	?	?	?	?	+	?	+
Morgan et al. [31]	–	?	+	+	+	?	+

Low risk of bias is “+”. High risk of bias is “-”. Unclear risk of bias is “?”