Table 2.
Intakes of vitamin D and sources of vitamin D during adolescence and relative risk (95% confidence interval) of proliferative BBD in NHSII
| Exposures | Quintile of vitamin D intake
|
P trend | ||||
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | ||
| Vitamin D (including supplements) | ||||||
| Intake (IU/day)* | 148 | 227 | 315 | 403 | 586 | |
| No. of BBD cases§/pys¶ | 148/51,664 | 145/52,181 | 128/51,734 | 145/52,003 | 116/52,245 | |
| Multivariate RR (95% CI)† | 1.00 (ref) | 0.98 (0.78, 1.24) | 0.88 (0.69, 1.12) | 1.00 (0.79, 1.26) | 0.79 (0.61, 1.01) | 0.07 |
| Additional adjustment for calcium† | 1.00 (ref) | 0.94 (0.73, 1.21) | 0.82 (0.62, 1.09) | 0.90 (0.67, 1.22) | 0.70 (0.51, 0.96) | 0.03 |
|
| ||||||
| Vitamin D (without supplements) | ||||||
| Intake (IU/day)* | 143 | 214 | 289 | 363 | 478 | |
| No. of BBD cases§/pys¶ | 150/51,758 | 126/52,006 | 146/51,861 | 135/51,858 | 125/52,345 | |
| Multivariate RR (95% CI)† | 1.00 (ref) | 0.86 (0.67, 1.09) | 0.98 (0.78, 1.24) | 0.92 (0.72, 1.17) | 0.84 (0.66, 1.07) | 0.28 |
| Additional adjustment for calcium† | 1.00 (ref) | 0.81 (0.62, 1.05) | 0.94 (0.71, 1.24) | 0.85 (0.62, 1.16) | 0.74 (0.52, 1.04) | 0.15 |
|
| ||||||
| Vitamin D from supplements | ||||||
| Intake (IU/day)* | 0 | 56 | 228 | 400 | ||
| No. of BBD cases§/pys¶ | 579/219,185 | 32/7,953 | 37/17,779 | 34/14,911 | ||
| Multivariate RR (95% CI)† | 1.00 (ref) | 1.61 (1.12, 2.31) | 0.78 (0.56, 1.09) | 0.88 (0.62, 1.25) | 0.23 | |
| Additional adjustment for calcium† | 1.00 (ref) | 1.61 (1.13, 2.31) | 0.78 (0.56, 1.09) | 0.88 (0.62, 1.25) | 0.23 | |
|
| ||||||
| Dairy vitamin D | ||||||
| Intake (IU/day)* | 57 | 117 | 175 | 255 | 361 | |
| No. of BBD cases§/pys¶ | 127/52,052 | 149/51,765 | 128/51,883 | 129/52,188 | 149/51,941 | |
| Multivariate RR (95% CI)† | 1.00 (ref) | 1.18 (0.93, 1.50) | 0.98 (0.76, 1.26) | 0.99 (0.77, 1.28) | 1.14 (0.90, 1.46) | 0.67 |
| Additional adjustment for non-dairy vitamin D† | 1.00 (ref) | 1.18 (0.93, 1.50) | 0.98 (0.76, 1.25) | 0.99 (0.76, 1.27) | 1.14 (0.89, 1.46) | 0.70 |
|
| ||||||
| Non-dairy vitamin D | ||||||
| Intake (IU/day)* | 48 | 62 | 76 | 107 | 209 | |
| No. of BBD cases§/pys¶ | 147/51,552 | 149/51,535 | 146/51,586 | 128/52,935 | 112/52,220 | |
| Multivariate RR (95% CI)† | 1.00 (ref) | 1.02 (0.81, 1.28) | 1.06 (0.84, 1.34) | 1.06 (0.82, 1.36) | 0.82 (0.64, 1.06) | 0.06 |
| Additional adjustment for dairy vitamin D† | 1.00 (ref) | 1.02 (0.81, 1.29) | 1.07 (0.84, 1.35) | 1.06 (0.82, 1.37) | 0.83 (0.64, 1.06) | 0.05 |
Values for vitamin D with and without supplements, and dairy vitamin D, are medians of nutrient intakes in each quintile, adjusted for total energy intake using the residual method. Values for vitamin D supplements and non-dairy vitamin D are medians of raw nutrient values in each quintile.
682 cases of proliferative BBD (with or without atypia) were diagnosed during the follow-up period 1991–2001.
The multivariate models are adjusted for age in months, time period (5 periods), total energy intake (quintiles), age at menarche (<12, 12, 13, or ≥ 14 years), menopausal status (premenopausal, postmenopausal, or uncertain), average body size between ages 5 and 10 years (somatotype pictogram 1, 1.5–2, 2.5–3, 3.5–4.5, or ≥ 5), family history of breast cancer in mother or sister (yes vs. no), alcohol intake between ages 18 and 22 years (0, <5, 5–14, or ≥ 15 grams/day), multivitamin use between ages 13 and 18 years (yes vs. no), recency and duration of OC use (never, past <4 years, past ≥ 4 years, current <4 years, or current ≥ 4 years), and parity and age at first birth (nulliparous; 1–2 pregnancies, age at first birth <25 years; 1–2 pregnancies, age at first birth 25–29 years; 1–2 pregnancies, age at first birth ≥ 30 years; ≥ 3 pregnancies, age at first birth <25 years; ≥ 3 pregnancies, age at first birth 25–29 years; or ≥ 3 pregnancies, age at first birth ≥ 30 years). The age-adjusted results are essentially the same, and only multivariate adjusted results are presented. Models with total vitamin D and vitamin D supplements as exposure variables are not adjusted for multivitamin use.