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 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Case | Control | Pdifference * | ||||||
| Characteristics † | ||||||||
| N | 208 | 623 | ||||||
| Age (y) | 62.2 (8.3) | 61.8 (8.4) | Matched | |||||
| Current smoker (%) | 18.8 | 17.2 | Matched | |||||
| BMI (kg/m2) | 26.6 (4.8) | 26.1 (5.3) | 0.05 | |||||
| History of diabetes (%) | 6.7 | 4.0 | 0.27 | |||||
| Parity ‡ | 2.8 (1.4) | 2.9 (1.4) | 0.15 | |||||
| Multivitamin use (%) | 42.8 | 36.8 | 0.12 | |||||
| Aspirin use (%) | 37.0 | 38.5 | 0.70 | |||||
| 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.