Table 3.
Studies which contributed to recommended upper intake levels for vitamin D.
| Dose | Interval | Duration | Basal 25(OH)D concentration nmol/L (ng/mL) | Final 25(OH)D concentration nmol/L (ng/mL) | |
|---|---|---|---|---|---|
| 1000 IU (25 μg) | Daily | 3 m | 43.3±16.8 (17.3±6.7) | 68.7±16.9 (27.5±6.8) | No significant change in serum calcium49 |
| 4000 IU (100 μg) | Daily | 3 m | 37.9 ±13.4 (15.2±5.4) | 96.4±14.6 (38.6±5.8) | No significant change in serum calcium49 |
| 12,000/24,000/48,000 IU (300/600/1200 μg) | Monthly | 1 y | 41.6, 39.5, 38.9 (16.6, 15.9, 15.6) | 55.9, 64.6, 79.0 (22.4, 25.8, 31.6) | No symptomatic case of hypercalcaemia when measured every 3 m170 |
| 400/4000/10,000 IU (10/100/250 μg) | Daily | 3 y | 76.3, 81.3, 78.4 (30.5, 32.5, 31.4) | 77.4, 132.2, 144.4 (30.9, 52.9, 57.8) | Serum calcium measured at 6-monthly intervals. Report mild dose-dependent hypercalcaemia171 |
| 50,000IU (1250 μg ) | Daily | 2 m | 735 (294) | Clinical signs of vitamin D toxicity: failure to thrive, dehydration, nausea, vomiting181 | |
| Milk over-fortified with vitamin D | 731±434 (292±174) | Hypercalcaemia182 |