Characteristic | Placebo (N = 96) | Selenium (N = 79) | Total (N = 175) | P value* |
Age | ||||
Mean (SD) | 60.9 (8.5) | 62.3 (8.9) | 61.6 (8.7) | 0.28 |
Median (Q1, Q3) | 59.5 (53.5, 68.5) | 64.0 (55.0, 70.0) | 62.0 (55.0, 69.0) | |
Body mass index | ||||
Mean (SD) | 29.8 (5.4) | 28.5 (5.0) | 29.2 (5.2) | 0.11 |
Median (Q1, Q3) | 28.9 (25.7, 32.8) | 27.8 (25.5, 31.6) | 28.3 (25.5, 32.6) | |
Selenium dietary intake (µg/day)† | ||||
Mean (SD) | 105.5 (48.4) | 105.9 (54.4) | 105.6 (51.0) | 0.96 |
Median (Q1, Q3) | 92.4 (73.6, 128.8) | 94.5 (72.9, 122.6) | 93.7 (73.3, 123.7) | |
Selenium supplemental intake (µg/day)† | ||||
Mean (SD) | 5.6 (7.1) | 6.6 (7.1) | 6.0 (7.1) | 0.35 |
Median (Q1, Q3) | 0.0 (0.0, 10.0) | 7.1 (0.0, 10.0) | 4.3 (0.0, 10.0) | |
Plasma selenium (ng/mL)‡ | ||||
Mean (SD) | 139.7 (23.8) | 136.8 (22.8) | 138.4 (23.3) | 0.42 |
Median (Q1, Q3) | 136.3 (123.9, 157.7) | 131.3 (118.1, 155.0) | 133.5 (122.5, 156.1) | |
Gender | ||||
Female | 27 (28.1%) | 31 (39.2%) | 58 (33.1%) | 0.12 |
Male | 69 (71.9%) | 48 (60.8%) | 117 (66.9%) | |
Ethnicity | ||||
Non-Hispanic | 91 (94.8%) | 77 (97.5%) | 168 (96.0%) | 0.37 |
Hispanic | 5 (5.2%) | 2 (2.5%) | 7 (4.0%) | |
Race | ||||
Other | 3 (3.1%) | 0 (0.0%) | 3 (1.7%) | 0.28 |
White | 92 (95.8%) | 78 (98.7%) | 170 (97.1%) | |
Mixed | 1 (1.0%) | 1 (1.3%) | 2 (1.1%) | |
Education | ||||
Some high school | 0 (0.0%) | 5 (6.3%) | 5 (2.9%) | 0.04 |
High school | 22 (22.9%) | 12 (15.2%) | 34 (19.4%) | |
Some college | 24 (25.0%) | 26 (32.9%) | 50 (28.6%) | |
College degree | 19 (19.8%) | 18 (22.8%) | 37 (21.1%) | |
Postgraduate | 31 (32.3%) | 18 (22.8%) | 49 (28.0%) | |
Cigarette smoking | ||||
Current smoker | 13 (13.8%) | 6 (7.8%) | 19 (11.1%) | 0.45 |
Previous smoker | 42 (44.7%) | 36 (46.8%) | 78 (45.6%) | |
Never Smoker | 39 (41.5%) | 35 (45.5%) | 74 (43.3%) | |
Diabetes | ||||
No diabetes | 94 (97.9%) | 78 (98.7%) | 172 (98.3%) | 0.68 |
Has diabetes | 2 (2.1%) | 1 (1.3%) | 3 (1.7%) | |
Personal history of cancer | ||||
Never had cancer | 89 (92.7%) | 78 (98.7%) | 167 (95.4%) | 0.06 |
Had cancer | 7 (7.3%) | 1 (1.3%) | 8 (4.6%) | |
Aspirin use in last 20 years | ||||
0–1 year | 58 (60.4%) | 45 (57.0%) | 103 (58.9%) | 0.86 |
1 to <5 years | 20 (20.8%) | 15 (19.0%) | 35 (20.0%) | |
5 to <10 years | 5 (5.2%) | 5 (6.3%) | 10 (5.7%) | |
10+ years | 13 (13.5%) | 14 (17.7%) | 27 (15.4%) | |
Non-steroidal anti-inflammatory drug use in last 20 years | ||||
0 to <1 year | 93 (96.9%) | 72 (91.1%) | 165 (94.3%) | 0.31 |
1 to <5 years | 2 (2.1%) | 3 (3.8%) | 5 (2.9%) | |
5 to <10 years | 0 (0.0%) | 2 (2.5%) | 2 (1.1%) | |
10+ years | 1 (1.0%) | 2 (2.5%) | 3 (1.7%) | |
Clinic | ||||
Phoenix | 69 (71.9%) | 57 (72.2%) | 126 (72.0%) | 0.68 |
Colorado | 11 (11.5%) | 7 (8.9%) | 18 (10.3%) | |
Tucson | 16 (16.7%) | 14 (17.7%) | 30 (17.1%) | |
Mayo | 0 (0.0%) | 1 (1.3%) | 1 (0.6%) |
*t-test or analysis of variance for continuous variables, χ2 categorical variables.
†From Arizona Food Frequency Questionnaire.
‡From baseline plasma.