Table 1. Summary of Our Prior 14C-Labeled Nutrient Studies (18−21) and Daily Reference Nutrient Amounts.
| α-tocopherol (20) |
||||||
|---|---|---|---|---|---|---|
| unit | β-carotene (18) | lutein (19) | RRRa | all-raca | folic acid (21) | |
| molecular weight | g/mol | 536.873 | 568.9 | 430.71 | 430.71 | 441.4 |
| specific activity, SA | Ci/mol | 98.8(18) | 0.2888 | 56 | 60 | 1.24b |
| gender | male (n = 4) | female (n = 1) | male (n = 1) | male (n = 1) | male (n = 7) | |
| female (n = 4) | female (n = 6) | |||||
| subject | kg | 76.7 ± 23.2 | 64.1 | 79.5 | 79.5 | 78.3 ± 0.28 |
| body mass index | kg/m2 | 25.0 ± 4.2 | 27.6 | 23.8 | 23.8 | 26.5 ± 5.9 |
| age | year | 35 ± 8.2 | 45 | 36 | 36 | 32 ± 0.38 |
| 14C dose (18−21) | nmol [nCi] | 1.01 [100] | 125 [36] | 1.821 [101.5] | 1.667 [99.98] | 0.5 [100] |
| ratio (mol/mol) between 14C dose (18−21) and Recommended Daily Allowance (RDA) or average intake (AI) in the U.S. | 1/6544 | 1/3 through 1/28 | 1/19124 | 1/20891 | 1/1812 (>19 years) 1/2719 (pregnancy) |
|
| reference nutrient amount/day | ||||||
| RDA or AI in the U.S. | mmol/day | 0.0066 (AI) (17) | 0.0003−0.0035 (AI) (38) | 0.0348 (>19 years) (RDA) (39) | 0.0009 (>19 years) 0.0014 (pregnancy) (RDA) (40) |
|
| therapeutic level | mmol/day | ≈0.32 (39) | 0.011−0.018 (38) | 0.12−7.43 (41) | 0.0005−0.022 (41) | |
| tolerable upper intake level/day | mmol/day | ndc(39) | nd (39) | 2.32 (>19 years) (39) | 0.0023 (>19 years) (40) | |
a
The study design was a test and retest in one subject.
b
SA was determined by using a mix of 0.5 nmol of 14C-folic acid and 79.5 nmol of nonlabeled cold folic acid.
c
The Institute of Medicine at the National Academy of Sciences did not establish a Tolerable Upper Intake Level (UL) for carotenoids when it reviewed these compounds in 2000.