Table 3.

Pooled estimates of flaxseed oil effects on antioxidant system function within different subgroups.

Variables	No. of studies	WMD or SMD (95% CI)	P value	I2 (%)	P heterogeneity
MDA
Total	8	−0.52 (−0.89, −0.15)	0.006	71.3	<0.001
FL dosage (mg)
≤2000	4	−0.84 (−1.11, −0.56)	<0.001	68.0	0.025
>2000	4	−0.14 (−0.43, 0.14)	0.311	—	0.398
Sample size
≤26	4	−0.53 (−0.83, −0.22)	<0.001	82.7	<0.001
>26	4	−0.48 (−0.74, −0.23)	<0.001	57.3	0.071
Intervention duration (week)
≤8	4	−0.53 (−0.83, −0.22)	<0.001	82.7	<0.001
>8	4	−0.48 (−0.74, −0.23)	<0.001	57.3	0.071
Mean age (years)
≤48	4	−0.43 (−0.71, −0.15)	0.002	84.6	<0.001
>48	4	−0.57 (−0.84, −0.29)	<0.001	32.6	0.217
Type of flaxseed
Flaxseed oil	5	−0.33 (−0.58, −0.08)	0.010	62.3	0.031
Omega-3 fatty acid from flaxseed oil	3	−0.78 (−1.10, −0.46)	<0.001	77.5	0.012
GSH
Total	4	0.45 (−0.12, 1.01)	0.122	77.9	0.004
Mean age (years)
≤48	1	1.19 (0.59, 1.79)	<0.001	—	—
>48	3	0.21 (−0.08, 0.51)	0.159	62.3	0.070
Type of flaxseed
Flaxseed oil	1	0.34 (−0.17, 0.85)	0.187	—	—
Omega-3 fatty acid from flaxseed oil	3	0.43 (0.12, 0.74)	0.007	85.2	0.001
TAC
Total	5	82.84 (19.80, 145.87)	0.010	92.7	<0.001
Mean age (years)
≤48	2	−0.02 (−0.03, −0.01)	0.003	66.0	0.086
>48	3	143.4(101.22, 185.61)	<0.001	72.7	0.026
Type of flaxseed
Flaxseed oil	2	−0.02 (−0.03, −0.01)	<0.001	66.0	0.003
Omega-3 fatty acid from flaxseed oil	3	46.88 (19.85, 73.92)	0.023	51.8	<0.001

MDA: malondialdehyde; GSH: glutathione; TAC: total antioxidant capacity; SMD: standardized mean difference; WMD: weighted mean difference; CI: confidence interval.