Table 3.
Total Intake of Selected Minerals 2–4 Years Before Reference Year and Risk of Premenstrual Syndrome, Nurses' Health Study II Premenstrual Syndrome Substudy, 1991–2001
| Mineral and Quintile | Median, mg/day | No. of Cases | No. of Controls | Age-adjusted RR | Model 1a |
Model 2b |
||
|---|---|---|---|---|---|---|---|---|
| RR | 95% CI | RR | 95% CI | |||||
| Iron | ||||||||
| 1 (Low) | 10.4 | 192 | 346 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 12.4 | 202 | 396 | 0.93 | 0.88 | 0.66, 1.15 | 0.82 | 0.61, 1.09 |
| 3 | 14.8 | 229 | 396 | 1.04 | 0.91 | 0.69, 1.21 | 0.83 | 0.61, 1.13 |
| 4 | 21.7 | 220 | 409 | 0.97 | 0.78 | 0.58, 1.05 | 0.67 | 0.48, 0.94 |
| 5 (High) | 49.2 | 212 | 417 | 0.89 | 0.69 | 0.50, 0.95 | 0.60 | 0.41, 0.86 |
| P for trend | 0.28 | 0.03 | 0.02 | |||||
| Heme iron | ||||||||
| 1 | 0.6 | 183 | 400 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 0.9 | 220 | 391 | 1.22 | 1.08 | 0.82, 1.41 | 1.12 | 0.85, 1.48 |
| 3 | 1.0 | 205 | 418 | 1.09 | 0.90 | 0.69, 1.18 | 0.93 | 0.70, 1.24 |
| 4 | 1.3 | 244 | 435 | 1.24 | 0.97 | 0.74, 1.27 | 1.00 | 0.75, 1.35 |
| 5 | 1.6 | 203 | 320 | 1.39 | 1.07 | 0.80, 1.43 | 1.14 | 0.81, 1.61 |
| P for trend | 0.01 | 0.75 | 0.56 | |||||
| Nonheme iron | ||||||||
| 1 | 9.4 | 218 | 385 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 11.4 | 205 | 399 | 0.91 | 0.90 | 0.69, 1.18 | 0.85 | 0.64, 1.13 |
| 3 | 14.1 | 220 | 384 | 1.00 | 0.95 | 0.72, 1.25 | 0.88 | 0.65, 1.20 |
| 4 | 21.4 | 206 | 397 | 0.91 | 0.81 | 0.60, 1.09 | 0.71 | 0.51, 1.00 |
| 5 | 49.2 | 206 | 399 | 0.88 | 0.71 | 0.52, 0.98 | 0.64 | 0.44, 0.92 |
| P for trend | 0.32 | 0.04 | 0.04 | |||||
| Magnesium | ||||||||
| 1 | 237 | 191 | 370 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 280 | 223 | 418 | 1.04 | 1.09 | 0.83, 1.44 | 1.06 | 0.77, 1.46 |
| 3 | 311 | 216 | 435 | 0.98 | 1.13 | 0.84, 1.51 | 1.05 | 0.72, 1.52 |
| 4 | 350 | 213 | 397 | 1.07 | 1.08 | 0.80, 1.47 | 0.89 | 0.58, 1.37 |
| 5 | 415 | 212 | 344 | 1.23 | 1.30 | 0.93, 1.80 | 0.91 | 0.56, 1.50 |
| P for trend | 0.09 | 0.16 | 0.51 | |||||
| Manganese | ||||||||
| 1 | 2.3 | 193 | 383 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 2.8 | 204 | 376 | 1.11 | 1.07 | 0.81, 1.41 | 1.07 | 0.80, 1.43 |
| 3 | 3.4 | 216 | 446 | 0.99 | 0.96 | 0.73, 1.25 | 0.96 | 0.70, 1.30 |
| 4 | 4.2 | 219 | 407 | 1.09 | 1.05 | 0.80, 1.38 | 1.06 | 0.76, 1.47 |
| 5 | 5.8 | 223 | 352 | 1.32 | 1.30 | 0.97, 1.73 | 1.30 | 0.90, 1.88 |
| P for trend | 0.03 | 0.06 | 0.13 | |||||
| Potassium | ||||||||
| 1 | 2,319 | 203 | 391 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 2,684 | 221 | 430 | 0.98 | 1.07 | 0.82, 1.39 | 1.02 | 0.76, 1.36 |
| 3 | 2,952 | 212 | 437 | 0.96 | 1.07 | 0.81, 1.40 | 1.03 | 0.75, 1.42 |
| 4 | 3,248 | 209 | 393 | 1.06 | 1.14 | 0.86, 1.52 | 1.11 | 0.78, 1.58 |
| 5 | 3,717 | 210 | 313 | 1.37 | 1.50 | 1.11, 2.03 | 1.46 | 0.99, 2.15 |
| P for trend | 0.01 | 0.01 | 0.04 | |||||
| Sodium | ||||||||
| 1 | 1,684 | 201 | 402 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 1,932 | 192 | 412 | 0.93 | 0.90 | 0.69, 1.18 | 0.90 | 0.69, 1.18 |
| 3 | 2,116 | 213 | 392 | 1.10 | 0.99 | 0.75, 1.29 | 1.00 | 0.76, 1.31 |
| 4 | 2,308 | 226 | 375 | 1.23 | 1.14 | 0.88, 1.50 | 1.13 | 0.86, 1.49 |
| 5 | 2,586 | 223 | 383 | 1.18 | 1.05 | 0.81, 1.38 | 1.04 | 0.79, 1.38 |
| P for trend | 0.04 | 0.28 | 0.37 | |||||
| Zinc | ||||||||
| 1 | 9.2 | 206 | 405 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 10.8 | 182 | 389 | 0.92 | 0.96 | 0.73, 1.26 | 0.94 | 0.71, 1.24 |
| 3 | 12.2 | 227 | 417 | 1.07 | 0.99 | 0.75, 1.29 | 0.97 | 0.74, 1.28 |
| 4 | 14.9 | 203 | 352 | 1.13 | 0.98 | 0.74, 1.31 | 1.03 | 0.76, 1.38 |
| 5 | 27.9 | 237 | 401 | 1.11 | 0.94 | 0.69, 1.29 | 0.96 | 0.65, 1.41 |
| P for trend | 0.24 | 0.75 | 0.92 | |||||
| Copper | ||||||||
| 1 | 1.0 | 182 | 395 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 1.2 | 268 | 515 | 1.17 | 1.19 | 0.92, 1.54 | 1.18 | 0.89, 1.57 |
| 3 | 1.3 | 138 | 321 | 0.98 | 1.01 | 0.74, 1.37 | 0.98 | 0.69, 1.39 |
| 4 | 1.5 | 245 | 397 | 1.39 | 1.30 | 0.98, 1.72 | 1.20 | 0.85, 1.69 |
| 5 | 2.9 | 222 | 336 | 1.43 | 1.33 | 0.97, 1.81 | 1.39 | 0.93, 2.08 |
| P for trend | 0.004 | 0.12 | 0.13 | |||||
| Zinc to copper ratioc | ||||||||
| 1 | 6.8 | 220 | 384 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 8.0 | 217 | 386 | 0.98 | 0.81 | 0.62, 1.06 | 0.85 | 0.63, 1.14 |
| 3 | 9.0 | 219 | 382 | 0.99 | 0.89 | 0.67, 1.17 | 0.97 | 0.70, 1.34 |
| 4 | 10.3 | 191 | 418 | 0.78 | 0.66 | 0.49, 0.88 | 0.72 | 0.49, 1.06 |
| 5 | 13.9 | 208 | 394 | 0.88 | 0.69 | 0.51, 0.95 | 0.82 | 0.51, 1.33 |
| P for trend | 0.15 | 0.03 | 0.59 | |||||
| Calcium to magnesium ratioc | ||||||||
| 1 | 1.2 | 211 | 392 | 1.00 | 1.00 | Referent | 1.00 | Referent |
| 2 | 1.6 | 236 | 368 | 1.18 | 1.39 | 1.04, 1.85 | 1.47 | 1.08, 2.01 |
| 3 | 1.9 | 202 | 402 | 0.91 | 1.96 | 0.69, 1.34 | 1.09 | 0.74, 1.60 |
| 4 | 2.2 | 216 | 388 | 0.99 | 0.98 | 0.67, 1.41 | 1.16 | 0.73, 1.85 |
| 5 | 2.9 | 190 | 414 | 0.83 | 0.85 | 0.55, 1.30 | 1.10 | 0.61, 1.98 |
| P for trend | 0.03 | 0.18 | 0.81 | |||||
Abbreviations: CI, confidence interval; RR, relative risk.
a Adjusted for age (<30, 30–34, 35–39 or ≥40 years), year of diagnosis (1993, 1994–1995, 1996–1996, 1998–1999, or 2000–2001), number of full-term pregnancies (0, 1–2, 3–4, or ≥5 pregnancies lasting ≥6 months), body mass index (weight (kg)/height (m)2) (<20.0, 20.0–22.4, 22.5–24.9, 25.0–27.4, 27.5–29.9, or ≥30.0), pack-years of smoking (quintiles), tubal ligation (no vs. yes), duration of oral contraceptive use (0, 1–23, 24–71, 72–119, or ≥120 months), antidepressant use (never vs. ever), history of childhood trauma score (5, 6–10, 11–15,or ≥16), and intakes of alcohol, vitamin B6, calcium, and vitamin D (quintiles). Heme iron was adjusted for nonheme iron and vice versa. Zinc to copper molar ratio was additionally adjusted for total zinc intake.
b Additionally adjusted for total intake of the other minerals in the table.
c Median values for ratios do not have units of measure.