. 2014 Nov 15;7(11):4461–4465.

Table 3.

Serum SOD activity and MDA content indexes comparison between experimental group and control group before and after intervention (n = 20, x̅ ± s)

Group	Case number (piece)	MDA (mol/mL)		SOD (U/mL)

		Before experiment	After experiment	Before experiment	After experiment
Control group	20	18.24 ± 4.61	16.41 ± 3.47	187.55 ± 18.86	216.46 ± 15.95
Mild smoking group	20	18.59 ± 3.12	22.31 ± 3.31^a,^b	187.34 ± 21.20	169.16 ± 24.80^a,^b
Heavy smoking group	20	18.37 ± 3.84	23.55 ± 2.37^a,^b	188.76 ± 18.74	154.91 ± 36.37^a,^b

Note: compared with the pre-intervention;

P < 0.05, compared with the control group;

P < 0.05.