Flaxseed Oil Supplementation Augments Antioxidant Capacity and Alleviates Oxidative Stress: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Table 2

Results of risk of bias assessment for randomized clinical trials included in the current meta-analysis on the effects of flaxseed oil supplementation on oxidative stress biomarkers¹.

Study	Random sequence generation	Allocation concealment	Reporting bias	Other sources of bias	Performance bias	Detection bias	Attrition bias
Pilar et al., 2014	U	U	L	U	H	H	H
Mirfatahi et al., 2016	L	L	H	U	L	H	L
Soleimani et al., 2017	L	L	L	L	L	L	L
Soleimani et al., 2017	L	L	L	L	L	H	L
Akrami et al., 2017	L	L	L	U	U	U	L
Raygan et al., 2019	L	L	L	L	L	L	L
Jamilian et al., 2020	L	L	L	L	L	L	L
Rezaei et al., 2020	L	L	L	U	L	L	L

¹Each study was assessed for risk of bias using the Cochrane risk of bias assessment tool [21]. Domains of assessment included random sequence generation, allocation concealment, reporting bias, performance bias, detection bias, attrition bias, and other sources of bias. Each domain was scored as “high risk” if it contained methodological flaws that may have affected the results, “low risk” if the flaw was deemed inconsequential, and “unclear risk” if information was insufficient to determine. If a study obtained “low risk” for all domains, it is considered as a high-quality study with totally low risk of bias.