Table 1. Participant characteristics and response to folic acid supplementation and termination of supplementation.
| Folic acid dosage | ||||||
| 100 µg/d | 400 µg/d | 4,000 µg/d | ||||
| Mean | SD | Mean | SD | Mean | SD | |
| Age | 30.6 | 4.1 | 30.7 | 3.7 | 29.9 | 4.4 |
| Body mass index | 23.5 | 3.9 | 24.1 | 4.9 | 24.2 | 4.3 |
| B12 (pmol/l) screening | 287.2 | 122.4 | 277.0 | 96.9 | 287.2 | 99.2 |
| Plasma folate (nmol/L) screening | 10.5 | 5.2 | 10.0 | 4.9 | 9.9 | 4.4 |
| 1 month | 19.5 | 8.1 | 31.4 | 12.2 | 103.0 | 129.3 |
| 3 months | 23.4 | 12.1 | 39.2 | 16.3 | 92.2 | 122.8 |
| 6 months | 36.7 | 70.1 | 40.9 | 19.8 | 56.3 | 34.3 |
| 3 months withdrawal (9 mo) | 16.2 | 5.5 | 17.4 | 6.3 | 19.2 | 5.8 |
| Red blood cell folate (nmol/L) screening | 685.2 | 292.8 | 669.7 | 365.6 | 685.1 | 309.7 |
| 1 month | 706.2 | 360.9 | 785.2 | 292.5 | 1031.0 | 470.9 |
| 3 months | 712.5 | 245.6 | 916.6 | 289.1 | 1543.8 | 707.0 |
| 6 months | 821.9 | 363.8 | 1147.8 | 546.3 | 1608.7 | 835.1 |
| 3 months withdrawal (9 mo) | 653.2 | 259.1 | 726.0 | 298.3 | 821.4 | 337.8 |
| Plasma homocysteine (Hcy)(µmol/L) screening | 8.2 | 4.4 | 8.9 | 6.5 | 8.9 | 5.4 |
| 1 month | 8.9 | 4.6 | 8.7 | 6.0 | 7.7 | 3.3 |
| 3 months | 7.0 | 3.6 | 6.5 | 4.2 | 6.2 | 3.0 |
| 6 months | 6.8 | 2.7 | 7.1 | 5.6 | 7.4 | 4.5 |
| 3 months withdrawal | 8.1 | 4.0 | 8.0 | 5.2 | 7.7 | 4.1 |
| Hemoglobin (Hgb) (g/L) screening | 138.3 | 9.6 | 135.7 | 9.0 | 133.6 | 8.1 |
| 6 months | 146.8 | 15.2 | 147.0 | 13.5 | 148.0 | 13.0 |
| 3 months withdrawal (9 mo) | 136.4 | 10.9 | 136.9 | 10.9 | 136.0 | 10.6 |