Selected subject characteristics at baseline and year 3
| Characteristic | Placebo (n = 461) | Folic acid (n = 462) | P | |||
|---|---|---|---|---|---|---|
| Mean age in y (SD) | 57.5 (9.6) | 57.7 (9.6) | 0.726 | |||
| Male sex n (%) | 297 (64.4) | 296 (64.1) | 0.910 | |||
| Race/Ethnicity n (%) | ||||||
| White | 405 (87.9) | 410 (88.7) | 0.695 | |||
| African American | 25 (5.4) | 20 (4.3) | ||||
| Hispanic | 17 (3.7) | 22 (4.8) | ||||
| Other | 14 (3.0) | 10 (2.2) | ||||
| Current cigarette smoker n (%) | 60 (13.1) | 70 (15.2) | 0.615 | |||
| Mean dietary intake in kcal/d (SD) | 1,642.3 (649.6) | 1,616.2 (656.8) | 0.552 | |||
| Mean dietary folate intake in μg/d (SD) | 329.0 (165.3) | 317.2 (145.1) | 0.260 | |||
| Mean baseline plasma folate in nmol/L (SD) | 23.7 (16.8) | 23.9 (18.1) | 0.873 | |||
| Mean year-3 plasma folate in nmol/L (SD) | 30.0 (14.1) | 74.9 (35.9) | <0.0001 | |||
| Mean baseline plasma T-homocysteine in μmol/L (SD) | 9.8 (2.9) | 9.8 (2.9) | 0.806 | |||
| Mean year-3 plasma T-homocysteine in μmol/L (SD) | 9.2 (2.5) | 8.9 (2.2) | 0.074 | |||
| MTHFR 677 C>T genotype | ||||||
| CC n (%) | 207 (45.0) | 213 (46.2) | 0.614 | |||
| CT n (%) | 201 (43.7) | 205 (44.5) | ||||
| TT n (%) | 52 (11.3) | 43 (9.3) | ||||
| MTHFR 1298 A>C genotype | ||||||
| AA n (%) | 234 (50.8) | 220 (47.6) | 0.283 | |||
| AC n (%) | 193 (41.9) | 195 (42.2) | ||||
| CC n (%) | 34 (7.4) | 47 (10.2) | ||||
| Joint genotypes (677/1298) | ||||||
| CC/AA (baseline) n (%) | 72 (15.7) | 71 (15.4) | ||||
| CC/AC n (%) | 101 (22.0) | 96 (20.8) | ||||
| CC/AA n (%) | 34 (7.4) | 46 (10.0) | 0.670 | |||
| CT/AA n (%) | 110 (23.9) | 106 (23.0) | ||||
| CT/AC n (%) | 91 (19.8) | 99 (21.5) | ||||
| CT/CC n (%) | 0 | 0 | ||||
| TT/AA n (%) | 52 (11.3) | 43 (9.3) | ||||
| TT/AC n (%) | 0 | 0 | ||||
| TT/CC n (%) | 0 | 0 | ||||
NOTE: Of the 1,021 subjects randomized to folate treatment or placebo, MTHFR 677C>T and MTHFR 1298A>C genotype data were available for for 923 subjects (90%) and of these subjects 23 did not have a year-3 colonoscopy and are not included in further analyses. Missing data: Smoking status, n = 4; Dietary folate, n = 36; Dietary intake, n = 36; Plasma folate, n = 67; Baseline HCY, n = 64; Year-3 plasma folate and HCY, n = 119.