TABLE 4.
Folate metabolites by DHFR 19 bp (rs70991108) genotype group in quintiles of folic acid intake in healthy young Irish adults1
| Folic acid intake |
|||||
| Q1 (n = 500) | Q2 (n = 501) | Q3 (n = 501) | Q4 (n = 501) | Q5 (n = 500) | |
| RBC folate, nmol/L | |||||
| wt/wt | 850 (661, 1120) | 949 (727, 1250) | 982 (796, 1300) | 1100 (881, 1370) | 1239 (954, 1620) |
| wt/del | 841 (659, 1060) | 917 (696, 1160) | 1020 (775, 1310) | 1110 (872, 1490) | 1220 (924, 1610) |
| del/del | 782 (634, 979) | 944 (692, 1100) | 1010 (810, 1220) | 1060 (826, 1450) | 1260 (962, 1580) |
| P | 0.09 | 0.85 | 0.81 | 0.34 | 0.96 |
| Serum folate, nmol/L | |||||
| wt/wt | 22.7 (15.9, 29.6) | 26.6 (19.6, 37.7) | 29.6 (23.1, 40.1) | 34.9 (24.3, 47.8) | 40.6 (27.8, 58.1) |
| wt/del | 23.0 (16.4, 30.7) | 26.3 (17.9, 37.4) | 29.4 (21.2, 41.9) | 36.1 (24.8, 50.7) | 43.0 (27.1, 59.2) |
| del/del | 21.2 (13.7, 30.3) | 26.6 (18.2, 37.7) | 31.7 (24.3, 41.3) | 36.0 (26.5, 53.7) | 45.3 (27.3, 60.5) |
| P | 0.48 | 0.43 | 0.82 | 0.23 | 0.56 |
| Plasma tHcy, μmol/L | |||||
| wt/wt | 9.4 (7.8, 11.2) | 8.3 (7.2, 9.8) | 8.2 (7.1, 9.4) | 7.6 (6.7, 9.1) | 7.7 (6.6, 8.6) |
| wt/del | 9.2 (7.8, 10.5) | 8.4 (7.1, 10.0) | 8.2 (7.0, 9.6) | 7.8 (6.8, 8.9) | 7.6 (6.6, 9.1) |
| del/del | 8.7 (7.4, 11.0) | 8.6 (7.3, 9.8) | 8.0 (6.9, 9.2) | 7.3 (6.5, 8.3) | 7.6 (6.7, 9.0) |
| P | 0.43 | 0.55 | 0.31 | 0.14 | 0.71 |
1
Values are medians (IQRs). Total folic acid intake was calculated as the average micrograms per day based on reported intake in the previous week from combined supplement use and folic acid from fortified foods. Range of folic intake: Q1, 0–51 μg/d; Q2, 52–104 μg/d; Q3, 105–192 μg/d; Q4, 193–327 μg/d; and Q5, 328–14,920 μg/d. P values were generated with the use of an F test by ANOVA on rank-based inverse normal transformations of the data. del, deletion; DHFR, dihydrofolate reductase; Q, quintile; tHcy, total homocysteine; wt, wild-type.