Table 1.

Selected subject characteristics at baseline and year 3

CharacteristicPlacebo (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 (%)
    White405 (87.9)410 (88.7)0.695
    African American25 (5.4)20 (4.3)
    Hispanic17 (3.7)22 (4.8)
    Other14 (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 (%)00
    TT/AA n (%)52 (11.3)43 (9.3)
    TT/AC n (%)00
    TT/CC n (%)00
  • 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.