Table 1.

Baseline Characteristics by Energy-adjusted Quintile of selenium intake in the Shanghai Women’s Health Study (SWHS; 1997–2000) and the Shanghai Men’s Health Study (SMHS; 2002–2006)

	Energy-adjusted Quintile of selenium intake										P value
	1		2		3		4		5
	Mean/%	SD	Mean/%	SD	Mean/%	SD	Mean/%	SD	Mean/%	SD
SWHS
Number of participants	14771	-	14771	-	14769	-	14771	-	14772
Age (years)	56.72	9.14	53.4	8.97	51.94	8.64	51.03	8.42	49.77	8.03	<0.0001
High educational level (%)†	2.07	-	4.08	-	5.5	-	6.06	-	5.89	-	<0.0001
High income (%)‡	10.02	-	14.95	-	18.43	-	20.7	-	23.78	-	<0.0001
Currently married (%)	83.83	-	89.22	-	90.07	-	91.04	-	90.29	-	<0.0001
Body mass index, kg/m2	24.87	3.69	24.13	3.44	23.82	3.38	23.73	3.25	23.56	3.22	<0.0001
Waist-to-hip ratio	0.82	0.06	0.81	0.05	0.81	0.05	0.81	0.05	0.80	0.05	<0.0001
Physical activity, MET-h/w/y§	109.42	45.69	107.98	45.72	105.86	44.61	105.26	44.48	103.71	44.56	<0.0001
Total energy intake, kcal/day	1580.99	396.44	1656.97	381.32	1687.19	377.31	1708.87	383.92	1739.03	411.1	<0.0001
Total fat, g/day	19.47	9.42	26.55	10.23	30.48	11.39	33.48	12.32	37.01	13.9	<0.0001
Ever smoker (%)	4.64	-	2.83	-	2.28	-	2	-	2.19	-	<0.0001
Alcohol drinking (ever) (%)	1.81	-	1.9	-	1.97	-	2.15	-	3.33	-	<0.0001
History of hypertension (%)	31.52	-	25.84	-	22.09	-	21.07	-	18.25	-	<0.0001
History of Coronary heart disease (%)	9.46	-	8.22	-	6.93	-	6.61	-	5.42	-	<0.0001
History of stroke (%)	2.15	-	1.37	-	0.99	-	0.69	-	0.58	-	<0.0001
Family history of cancer (%)	23.33	-	26.63	-	27.77	-	27.81	-	27.9	-	<0.0001
History of diabetes (%)	4.85	-	4.89	-	4.24	-	4.16	-	3.63	-	<0.0001
Supplement use (%)||	24.15	-	29.19	-	31.61	-	34.75	-	35.6	-	<0.0001
Postmenopausal (%)	67.48	-	53.73	-	46.88	-	42.33	-	36.98	-	<0.0001
SMHS
Number of subjects	12021	-	12022	-	12022	-	12016	-	12022	-
Age (years)	57.1	10.06	56.11	9.78	55.6	9.64	54.88	9.53	53.11	9.23	<0.0001
High educational level (%)†	6.77	-	10.44	-	12.63	-	13.71	-	13.89	-	<0.0001
High income (%)‡	4.77	-	7.62	-	9.87	-	11.79	-	14.37	-	<0.0001
Currently married (%)	82.41	-	85.15	-	85.67	-	85.49	-	83.7	-	<0.0001
Body mass index, kg/m2	23.79	3.12	23.75	3.09	23.7	3.07	23.74	3.07	23.63	3.04	0.001
Waist-to-hip ratio	0.90	0.06	0.90	0.06	0.90	0.06	0.90	0.06	0.90	0.06	<0.0001
Physical activity, MET-h/w/y§	62.79	35.28	60.8	33.73	59.87	34.26	58.55	33.25	56.41	34.06	<0.0001
Total energy intake, kcal/day	1892.54	476.06	1906.29	463.51	1914.39	463.84	1915.61	466.66	1921.87	502.04	<0.0001
Total fat, g/day	24.34	11.13	31.25	11.99	35.28	13.72	38.71	14.75	43.25	17.87	<0.0001
Current Smoking (%)	56.89	-	55.97	-	57.54	-	58.82	-	64.38	-	<0.0001
Current alcohol consumption (%)	19.03	-	23.32	-	28.89	-	32.08	-	42.8	-	<0.0001
History of hypertension (%)	32.93	-	31.52	-	29.75	-	29.21	-	25.83	-	<0.0001
History of Coronary heart disease (%)	5.76	-	5.4	-	5.32	-	5.06	-	3.99	-	<0.0001
History of diabetes (%)	4.67	-	5.8	-	6.39	-	7.5	-	6.99	-	<0.0001
History of stroke (%)	5.53	-	4.3	-	3.7	-	3.01	-	2.3	-	<0.0001
Family history of cancer (%)	26.65	-	28.32	-	29.35	-	28.86	-	28.76	-	<0.0001
Supplement use (%)||	11.72	-	16.49	-	18.47	-	20.02	-	20.48	-	<0.0001

The median and cut points for the quintile of Se intake in the SWHS were 15.86 (7.19–19.04), 21.16 (19.05–23.15), 25.18 (23.16–27.31), 30.02 (27.32–33.35) and 42.22 (33.36–124.64) μg/4184KJ (1000kcal) per d and in the SMHS were 16.46 (7.43–19.36), 21.33 (19.37–23.20), 25.09 (23.21–27.11), 29.72 (27.12–32.91), 41.70 (32.92–165.38) μg/4184KJ (1000kcal) per d.

^†High educational level was defined as having a college degree or above.

^‡High income was defined as a family income greater than 30,000 Yuan per year for women or a personal income greater than 2,000 Yuan per month for men.

^§Physical activity: metabolic equivalent (MET)-hours per week per year (1 MET h=15 min of moderate intensity activity).

^||Use of any vitamin A, B, C, or E supplements, multivitamins or calcium.