TABLE 1.
Baseline characteristics of the study participants and subgroup analysis of OC use1
| All participants | OC user (n = 25) | No OC (n = 14) | P value | |
| Age (y) | 22.4 ± 2.3 (19–27)2 | 22.2 ± 2.2 | 23.0 ± 2.5 | 0.29 |
| Weight (kg) | 61.2 ± 7.2 (45.6–77.3) | 60.4 ± 6.4 | 62.7 ± 8.3 | 0.35 |
| BMI (kg/m2) | 22.3 ± 2.2 (18.6–26.0) | 22.0 ± 2.1 | 22.6 ± 2.3 | 0.39 |
| Fat mass (%) | 26.6 ± 6.1 (13.2–41.9) | 26.3 ± 4.9 | 26.8 ± 8.1 | 0.84 |
| Energy intake (kcal/d)3 | 1768 ± 578 (555–3600) | 1648 ± 486 | 2034 ± 650 | 0.042 |
| Protein intake (g/d)3 | 73 ± 26 (30–151) | 67 ± 21 | 85 ± 30 | 0.031 |
| Total fat intake (g/d)3 | 57 ± 23 (19–123) | 54 ± 20 | 64 ± 27 | 0.22 |
| Vitamin A intake including supplements, by FFQ (RAE/d)3 | 1213 ± 778 (378–3890) | 1035 ± 588 | 1479 ± 999 | 0.088 |
| Vitamin A intake excluding supplements, by FFQ (RAE/d)3 | 811 ± 405 (259–2190) | 706 ± 281 | 1026 ± 514 | 0.046 |
| Vitamin A intake, by 3DDR (RAE/d)4 | 1180 ± 705 (78–3020) | 1009 ± 591 | 1478 ± 850 | 0.077 |
| Reporting supplement use on FFQ [n (%)] | 40 (16) | 40 (10) | 43 (6) | 0.67 |
| Reporting supplement use on 3DDR [n (%)]5 | 9 (3) | 5 (1) | 18 (2) | 0.43 |
| Serum retinol (μmol/L)5 | 2.68 ± 0.88 (0.81–5.89) | 2.68 ± 0.69 | 2.69 ± 1.3 | 0.96 |
| Total-body vitamin A (μmol)6 | 816.5 ± 537.4 (141.5–3116) | 854.8 ± 639.5 | 731.2 ± 289.7 | 0.51 |
| Hepatic vitamin A (μmol/g)7 | 0.45 ± 0.31 (0.09–1.79) | 0.48 ± 0.37 | 0.40 ± 0.18 | 0.48 |
n = 40, except where indicated. P < 0.01 was considered significant (multiple post hoc comparisons; t tests or chi-square tests were used to compare groups). FFQ, food-frequency questionnaire; OC, oral contraceptive; RAE, retinol activity equivalents [where 1 RAE = 1 μg all-trans-retinol, 2 μg supplemental all-trans-β-carotene, 12 μg dietary all-trans-β-carotene, or 24 μg of all other provitamin A carotenoids (ie, α-carotene and β-cryptoxanthin)]; 3DDR, 3-d diet record.
Mean ± SD; range in parentheses (all such values).
Baseline dietary intake evaluated by using the Harvard FFQ.
Baseline dietary intake evaluated by using the 3DDR, n = 33. Includes supplements/vitamin pills.
n = 33.
Calculated by using Equations 1 and 2 (see Subjects and Methods for details), n = 39.
Calculated by assuming that 80% total-body vitamin A is stored in the liver and a liver weight of 2.4% body weight (see Subjects and Methods for additional details), n = 39.