Table 2.

The variation of biomarker levels with smoking status and dietary supplementation among the participants

	N	Mean (SD)	Range	P	Estimate (95% CI)
Serum selenium
Supplements
No	275	109.93 (1.2)	63.96–195.03	0.052	0.95 (0.91–0.99)
Yes
(without Se)	135	111.35 (1.19)	63.17–181.61		0.96 (0.91–1.01)
(with Se)	87	116.17 (1.22)	78.96–222.67		1.00
Smoking status
Current	27	102.3 (1.2)	65.5–150.0	0.020	0.92 (0.85–0.99)
Ex-smoker	148	112.9 (1.2)	63.1–195.0	0.506	1.01 (0.98–1.05)
Non smoker	322	111.5 (1.2)	72.6–222.7		1.00
TR activity
Supplements
No	275	1.11 (0.76)	0–3.78	0.912
Yes
(without Se)	135	0.99 (0.75)	0–3.26
(with Se)	87	1.15 (0.76)	0–3.26
Smoking status
Current	27	1.08 (0.63)	0–2.84	0.218
Ex-smoker	148	1.10 (0.79)	0–3.68
Non smoker	322	1.07 (0.76)	0–3.78
GPx activity
Supplements
No	275	14.18 (6.97)	0.83–37.57	0.616
Yes
(without Se)	135	14.93 (7.78)	0.83–38.81
(with Se)	87	14.4 (7.18)	2.06–33.86
Smoking status
Current	27	13.58 (7.15)	2.48–33.86	0.199
Ex-smoker	148	13.64 (6.87)	2.89–37.57
Non smoker	322	14.85 (7.38)	0.83–38.81
Fresh blood DNA damage
Supplements
No	275	5.96 (1.41)	3.12–12.37	0.431
Yes
(without Se)	135	6.01 (1.37)	3.14–11.03
(with Se)	87	6.19 (1.34)	3.72–11.57
Smoking status
Current	27	5.96 (1.38)	4.41–9.57	0.567
Ex-smoker	148	5.92 (1.38)	3.22–11.03
Non smoker	322	6.06 (1.4)	3.12–12.37
Peroxide challenged DNA damage
Supplements
No	275	7.37 (1.6)	3.83–12.19	0.408
Yes
(without Se)	135	7.57 (1.81)	2.97–14.78
(with Se)	87	7.67 (1.82)	4.53–13.22
Smoking status
Current	27	7.52 (1.7)	4.5–14.69	0.859
Ex-smoker	148	7.36 (1.85)	3.83–13.22
Non smoker	322	7.55 (1.78)	2.97–14.78

Estimate is the relative mean difference between two groups

Bold values are statistically significant