Table 2.
RRs and 95% CI for vitamin D and dairy intake during adolescence and MS, NHS (1976–2004) and NHSII (1989–2005)
| NHS | NHSII | Multivariateb Pooled | |||||
|---|---|---|---|---|---|---|---|
| Median (IU/day) |
Incidenta cases/py |
Median (IU/day) |
Incidenta cases/py |
Prevalenta cases/py |
Incident RR (95% CI) |
Incident and prevalent RR (95% CI) |
|
| Total vitamin D | |||||||
| Quintile 1 | 143 | 28/396,481 | 148 | 41/142,419 | 15/70,091 | 1 | 1 |
| Quintile 2 | 230 | 36/399,926 | 227 | 32/142,750 | 20/70,046 | 0.97 (0.60, 1.57) | 1.04 (0.73, 1.48) |
| Quintile 3 | 304 | 35/402,704 | 316 | 43/142,190 | 12/70,542 | 1.08 (0.78, 1.50) | 1.03 (0.76, 1.39) |
| Quintile 4 | 386 | 43/400,735 | 404 | 47/142,520 | 10/70,545 | 1.22 (0.89, 1.68) | 1.12 (0.80, 1.56) |
| Quintile 5 | 695 | 35/397,520 | 586 | 39/142,381 | 10/69,328 | 0.99 (0.71, 1.38) | 0.94 (0.69, 1.28) |
| Total | 177/1,997,367 | 202/712,260 | 67/350,552 | ||||
| P trendc | 0.93 | 0.66 | |||||
| P hetd | 0.71 | 0.31 | |||||
| Vitamin D supplements only | |||||||
| 0 | 0 | 144/1,649,117 | 0 | 174/598,924 | 58/296,409 | 1 | 1 |
| <400 | 70 | 11/105,999 | 228 | 22/71,727 | 7/33,974 | 1.03 (0.72, 1.48) | 1.04 (0.75, 1.44) |
| ≥400 | 500 | 22/242,250 | 400 | 6/41,609 | 2/20,169 | 0.72 (0.43, 1.21) | 0.73 (0.50, 1.07) |
| Total | 177/1,997,367 | 202/712,260 | 67/350,552 | ||||
| P trend | 0.23 | 0.18 | |||||
| P het | 0.51 | 0.78 | |||||
| Non-dairy vitamin D | |||||||
| Quintile 1 | 39 | 30/395,878 | 34 | 48/142,205 | 11/74,971 | 1 | 1 |
| Quintile 2 | 67 | 35/403,269 | 45 | 33/142,463 | 21/74,322 | 0.83 (0.58,1.18) | 1.03 (0.62, 1.72) |
| Quintile 3 | 97 | 44/402,256 | 58 | 48/142,458 | 11/67,653 | 1.15 (0.84, 1.56) | 1.14 (0.85, 1.52) |
| Quintile 4 | 146 | 32/396,419 | 110 | 42/142,514 | 16/64,913 | 0.91 (0.66, 1.27) | 1.00 (0.74, 1.36) |
| Quintile 5 | 541 | 36/399,546 | 236 | 31/142,619 | 8/68,693 | 0.78 (0.55, 1.08) | 0.78 (0.57, 1.07) |
| Total | 177/1,997,367 | 202/712,260 | 67/350,552 | ||||
| P trend | 0.27 | 0.16 | |||||
| P het | 0.27 | 0.37 | |||||
| Dairy vitamin D | |||||||
| Quintile 1 | 52 | 28/396,904 | 57 | 45/142,595 | 13/68,490 | 1 | 1 |
| Quintile 2 | 128 | 41/398,965 | 117 | 26/142,571 | 19/69,073 | 0.88 (0.37, 2.08) | 1.01 (0.54, 1.88) |
| Quintile 3 | 190 | 39/402,127 | 176 | 38/142,347 | 15/70,548 | 1.02 (0.64, 1.63) | 1.02 (0.75, 1.39) |
| Quintile 4 | 255 | 37/404,259 | 256 | 45/142,468 | 9/70,964 | 1.06 (0.77, 1.46) | 1.00 (0.74, 1.34) |
| Quintile 5 | 359 | 32/395,112 | 362 | 48/142,278 | 11/71,477 | 1.07 (0.77, 1.48) | 1.03 (0.76, 1.39) |
| Total | 177/1,997,367 | 202/712,260 | 67/350,552 | ||||
| P trend | 0.35 | 0.90 | |||||
| P het | 0.47 | 0.23 | |||||
| Total dairye | |||||||
| <1 servings/day | 15/205,228 | 12/45,437 | 2/23,701 | 1 | 1 | ||
| 1 to <2 | 39/407,293 | 35/137,041 | 14/67,045 | 1.10 (0.70, 1.71) | 1.16 (0.76, 1.78) | ||
| 2 to <3 | 29/354,834 | 27/140,772 | 20/67,925 | 0.85 (0.53, 1.36) | 0.99 (0.56, 1.76) | ||
| 3 to <4 | 31/404,657 | 49/154,106 | 14/76,097 | 1.02 (0.64, 1.62) | 1.07 (0.68, 1.66) | ||
| 4 to <5 | 23/184,227 | 30/107,698 | 8/52,852 | 1.24 (0.75, 2.05) | 1.25 (0.78, 2.02) | ||
| 5 to <6 | 20/228,900 | 23/58,667 | 2/29,012 | 1.26 (0.75, 2.14) | 1.21 (0.73, 2.01) | ||
| ≥6 | 20/212,227 | 26/68,540 | 7/34,514 | 1.25 (0.72, 2.18) | 1.29 (0.76, 2.18) | ||
| Total | 177/1,997,367 | 202/712,260 | 67/350,552 | ||||
| P trend | 0.10 | 0.29 | |||||
| P het | 0.43 | 0.31 | |||||
| Total milk | |||||||
| <1 servings/day | 57/692,596 | 68/250,359 | 25/123,016 | 1 | 1 | ||
| 1 to <2 | 39/380,460 | 34/156,801 | 20/76,301 | 0.97 (0.63, 1.49) | 1.03 (0.76, 1.39) | ||
| 2 to <3 | 62/785,972 | 75/237,315 | 15/118,111 | 1.00 (0.76, 1.32) | 0.90 (0.66, 1.25) | ||
| ≥3 | 19/138,339 | 25/67,785 | 7/33,124 | 1.38 (0.94, 2.02) | 1.30 (0.92, 1.84) | ||
| Total | 177/1,997,367 | 202/712,260 | 67/350,552 | ||||
| P trend | 0.29 | 0.84 | |||||
| P het | 0.46 | 0.16 | |||||
| Total whole milk | |||||||
| <1 servings/day | 67/789,381 | 110/407,655 | 37/191,340 | 1 | 1 | ||
| 1 to <2 | 34/358,314 | 21/104,276 | 16/53,694 | 0.90 (0.57, 1.42) | 1.03 (0.69, 1.53) | ||
| 2 to <3 | 61/730,412 | 51/154,238 | 7/81,826 | 1.05 (0.81, 1.36) | 0.88 (0.57, 1.35) | ||
| ≥3 | 15/119,260 | 20/46,091 | 7/23,692 | 1.49 (1.00, 2.22) | 1.47 (1.03, 2.11) | ||
| Total | 177/1,997,367 | 202/712,260 | 67/350,552 | ||||
| P trend | 0.17 | 0.45 | |||||
| P het | 0.46 | 0.32 | |||||
NHS Nurses’ Health Study; NHSII Nurses’ Health Study II; RR relative risk; CI confidence interval; MS multiple sclerosis; IU International Units; py person–years
Incident cases diagnosed between 1976–June 2004 (NHS) and between 1989–June 2005 (NHSII); prevalent cases diagnosed before 1989 (NHSII)
Adjusted for age (months), 2-year time periods, total caloric intake (kcal/day) (except supplemental vitamin D), latitude of residence age 15 (north, middle, south), ethnicity (Scandinavian, Southern European, other Caucasian, other), pack-years smoking (never,<10, 10–24, >24)
P value for linear trend calculated from Cox proportional hazards models
P value for heterogeneity of the pooled effect estimate from Chi-squared test
Total dairy: non/low-fat milk, whole milk, milkshake/frappe, ice cream, cheese, butter; NHSII only also included: chocolate milk, sherbet, yogurt, cottage/ricotta cheese, instant breakfast drink, cream cheese, pudding