| NHS subjects in 1990 (ages 44–69) | NHSII subjects in 1991 (ages 27–44) | |||||||||
| Quintiles of vitamin D intake* | Quintiles of vitamin D intake† | |||||||||
| 1 | 2 | 3 | 4 | 5 | 1 | 2 | 3 | 4 | 5 | |
| Age in years, mean | 56 | 56 | 57 | 57 | 58 | 37 | 37 | 37 | 36 | 36 |
| White race, % | 98 | 98 | 98 | 98 | 98 | 96 | 97 | 98 | 98 | 97 |
| Smoking status | ||||||||||
| Past smoker, % | 34 | 37 | 37 | 38 | 39 | 20 | 22 | 23 | 23 | 24 |
| Current smoker, % | 21 | 17 | 16 | 15 | 14 | 17 | 13 | 11 | 11 | 10 |
| Age at menarche ⩽10 years, % | 6 | 6 | 6 | 6 | 7 | 8 | 8 | 8 | 8 | 8 |
| Oral contraceptive ever use, % | 48 | 47 | 49 | 50 | 51 | 85 | 85 | 85 | 84 | 84 |
| Parous, % | 91 | 92 | 92 | 92 | 91 | 74 | 75 | 75 | 74 | 69 |
| Lifetime breast-feeding ⩾12 months, among parous women, % | 15 | 18 | 20 | 21 | 20 | 33 | 39 | 44 | 45 | 45 |
| Postmenopausal, % | 68 | 69 | 69 | 70 | 69 | 4 | 3 | 3 | 3 | 4 |
| Current use of postmenopausal hormones, among postmenopausal, % | 17 | 19 | 21 | 24 | 25 | 82 | 83 | 81 | 85 | 83 |
| Physical exercise, >3 h/week | 22 | 27 | 30 | 31 | 32 | 66 | 71 | 74 | 75 | 76 |
| Body mass index (kg/m2) | 23 | 23 | 24 | 24 | 23 | 25 | 25 | 25 | 24 | 24 |
| Lived in south‡ at age 15 (%) | 28 | 32 | 34 | 34 | 31 | 25 | 29 | 32 | 32 | 32 |
| Ultraviolet index ⩾7§ in state age 15 (%) | 10 | 10 | 10 | 11 | 11 | 22 | 21 | 19 | 20 | 21 |
| Natural dark brown/black hair colour (%) | 42 | 42 | 42 | 41 | 40 | 43 | 43 | 41 | 41 | 41 |
| Usually no sunburn (%) | 56 | 57 | 58 | 56 | 56 | 54 | 53 | 52 | 52 | 51 |
| Husband >college education (%) | 15 | 17 | 18 | 18 | 17 | 21 | 23 | 25 | 25 | 26 |
| Daily multivitamin use (%) | 4 | 11 | 24 | 45 | 62 | 8 | 16 | 30 | 70 | 96 |
| Mean daily intake: | ||||||||||
| Alcohol (g) | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 |
| Caffeine (mg) | 301 | 279 | 260 | 248 | 228 | 268 | 259 | 243 | 227 | 196 |
| Calcium (mg) | 698 | 839 | 967 | 1095 | 1301 | 687 | 846 | 1028 | 1162 | 1373 |
| Protein¶ (g) | 71 | 75 | 77 | 78 | 79 | 80 | 85 | 88 | 89 | 90 |
| Vitamin A¶ (μg) | 956 | 1179 | 1435 | 1956 | 2989 | 810 | 1011 | 1245 | 1874 | 3192 |
*NHS quintile cut-offs: 1 = 2–160.25; 2 = >160.25–234.4; 3 = >234.4–333.6; 4 = >333.6–489.1; 5 = >489.1–3964.8.
†NHSII quintile cut-offs: 1 = 3–187.9; 2 = >187.9–280.9; 3 = >280.9–392.0; 4 = >392.0–558.7; 5 = >558.7–5203.0.
‡Southern states and territories: Alabama, Arizona, Arkansas, Southern California, Florida, Georgia, Hawaii, Louisiana, Mississippi, New Mexico, North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas.
§Ultraviolet index based on the mean for the month of August for state of residence.
¶Nutrients include intakes from food plus supplements, adjusted for total energy intake.
NHS, Nurses' Health Study; NHSII, Nurses' Health Study II.