Table 1.

Baseline characteristics and plasma concentration of one-carbon nutrients

(A) Baseline characteristics and plasma concentrations of folate, vitamin B6, vitamin B12, and homocysteine by case or control status
CaseControlPdifference *
Characteristics
    N208623
    Age (y)62.2 (8.3)61.8 (8.4)Matched
    Current smoker (%)18.817.2Matched
    BMI (kg/m2)26.6 (4.8)26.1 (5.3)0.05
    History of diabetes (%)6.74.00.27
    Parity 2.8 (1.4)2.9 (1.4)0.15
    Multivitamin use (%)42.836.80.12
    Aspirin use (%)37.038.50.70
    Alcohol intake (g/d)9.7 (13.9)9.3 (12.4)0.91
    Total energy intake (kcal) §1,675 (555)1,739 (619)0.35
    Total folate intake (μg/d) §586 (292)551 (288)0.18
    Folate from food only (μg/d) §290 (128)289 (128)0.95
    Total B6 intake (mg/d) §9.0 (24.8)10.3 (37.6)0.62
    B6 from food only (mg/d) §1.8 (0.8)1.9 (0.8)0.51
    Total B12 intake (μg/d) §14.8 (42.3)16.4 (45.0)0.92
    B12 from food only (μg/d) §6.5 (3.6)7.1 (4.5)0.20
Plasma concentrations
    Folate (ng/mL)7.1 (6.6–7.7)7.0 (6.7–7.3)0.59
    Vitamin B6 (pmol/mL)12.7 (11.2–14.3)12.7 (11.9–13.6)0.95
    Vitamin B12 (pg/mL)520 (490–551)523 (504–542)0.87
    Homocysteine (nmol/mL)10.6 (10.2–11.1)10.6 (10.3–10.8)0.79
Plasma concentrations among nonusers of multivitamins
    Folate (ng/mL)5.7 (5.2–6.1)6.1 (5.8–6.4)0.10
    Vitamin B6 (pmol/mL)9.4 (8.1–10.8)10.6 (9.8–11.4)0.13
    Vitamin B12 (pg/mL)467 (432–505)488 (467–510)0.33
    Homocysteine (nmol/mL)11.1 (10.6–11.7)10.8 (10.5–11.2)0.30
(B) Cohort-specific plasma concentrations of folate, vitamin B6, vitamin B12, and homocysteine (controls only)
Plasma concentrations NHS (n = 146) **HPFS (n = 96) **PHS (n = 171) **WHI (n = 222) **
Folate (ng/mL)7.8 (7.1–8.5)6.5 (5.8–7.2)4.5 (4.2–4.8)9.1 (8.5–9.7)
Vitamin B6 (pmol/mL)10.8 (9.3–12.6)15.8 (13.5–18.7)12.5 (11.2–13.9)12.9 (11.5–14.5)
Vitamin B12 (pg/mL)520 (480–564)564 (516–617)427 (401–455)585 (551–621)
Homocysteine (nmol/mL)11.6 (11.0–12.2)13.3 (12.5–14.2)10.7 (10/2–11.3)8.9 (8.4–9.3)
  • * Data are presented as mean, with SD given in parentheses.

  • P values for comparison of mean natural methyl biomarker plasma levels between cases and controls based on mixed-effects regression models with adjustment for the matching variables (age, smoking status) and cohort/gender.

  • NHS and WHI; number of term pregnancies among parous women only.

  • § Not available for PHS cohort.

  • Data are presented as geometric mean (95% CI).

  • Data are presented as geometric mean (95% CI).

  • ** Numbers vary slightly by assay because of missing values.