Table 2. Mean folate intake, serum folate, erythrocyte folate, plasma homocysteine and [3H]methyl incorporation in colonic DNA for all subjects and according to MTHFR, MS and CBS genotypes.
| Folate intake (μg day−1)a | Serum folate (μg l−1) | Erythrocyte folate (μg l−1) | Plasma homocysteine (μmol L−1) | [3H]methyl incorporation in colonic DNA (Bq μg DNA−1)b | ||
|---|---|---|---|---|---|---|
| n (%) | Mean (95% CI)c | Mean (95% CI)c | Mean (95% CI)d | Mean (95% CI)d | Mean (95% CI)c | |
| All | 68 (100) | 359 (329–390) | 8.2 (7.5–9.0) | 296 (271–323) | 10.9 (9.9–12.0) | 394 (352–439) |
| MTHFR 677C → T | ||||||
| CC | 38 (56) | 378 (337–419) | 9.3 (8.3–10.3) | 303 (268–343) | 9.9 (8.8–11.1) | 381 (321–440) |
| CT | 24 (35) | 326 (272–380) | 7.4 (6.1–8.7) | 279 (236–326) | 10.8 (9.3–12.5) | 407 (330–484) |
| TT | 6 (9) | 362 (260–464) | 5.1 (2.5–7.8) | 318 (230–438) | 20.8 (15.4–28.3) | 447 (291–603) |
| P=0.35 | P=0.007 | P=0.66 | P=0.0002 | P=0.69 | ||
| MTHFR 1298A → C | ||||||
| AA | 44 (65) | 355 (315–394) | 8.1 (7.1–9.2) | 301 (268–337) | 10.8 (9.6–12.2) | 408 (352–464) |
| AC | 22 (32) | 365 (311–418) | 8.3 (6.8–9.8) | 291 (247–344) | 11.5 (9.6–13.8) | 389 (309–468) |
| CC | 2 (3) | 395 (226–565) | 9.9 (5.1–14.7) | 244 (143–417) | 7.6 (4.3–13.4) | 209 (47–465) |
| P=0.91 | P=0.78 | P=0.75 | P=0.37 | P=0.33 | ||
| MS 2756A → G | ||||||
| AA | 41 (60) | 354 (315–393) | 8.4 (7.3–9.4) | 283 (252–318) | 10.7 (9.4–12.2) | 438 (383–492) |
| AG | 19 (28) | 359 (302–415) | 8.0 (6.5–9.6) | 322 (271–382) | 11.5 (9.5–13.9) | 317 (233–400) |
| GG | 8 (12) | 390 (296–485) | 8.2 (5.7–10.7) | 304 (230–401) | 10.6 (7.8–14.3) | 359 (230–489) |
| P=0.86 | P=0.94 | P=0.47 | P=0.81 | P=0.05 | ||
| CBS 844ins68 | ||||||
| Wild type | 51 (75) | 355 (321–390) | 8.3 (7.3–9.2) | 286 (258–317) | 10.8 (9.6–12.0) | 404 (352–455) |
| 844ins68 | 17 (25) | 372 (310–435) | 8.2 (6.5–9.9) | 328 (273–395) | 11.4 (9.3–14.0) | 372 (282–463) |
| P=0.60 | P=0.96 | P=0.22 | P=0.61 | P=0.57 | ||
MTHFR=methylenetetrahydrofolate reductase; MS=methionine synthase; CBS=cystathionine synthase.
a
(n=61).
b
(n=67).
c
Arithmetic or
d
Geometric means (with 95% CI in parentheses) adjusted for gender, age, BMI and smoking. The P-values relate to tests of heterogeneity between the means arising from the relevant F-test statistic in the analysis of variance table.