TABLE 1.
Baseline characteristics of Women's Health Initiative (WHI) observational and clinical trial participants by quartile (Q) of total n−3 fatty acid (FA) intake1
| Total n−3 FA intake |
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| Characteristics | WHI cohort | Q1(<0.581% of energy) | Q2(0.581–0.736% of energy) | Q3(0.737–0.932% of energy) | Q4(>0.932% of energy) | P value |
| No. of subjects | 137,486 | 34,345 | 34,492 | 34,213 | 34,436 | |
| Age at screening (y) | 63 ± 72 | 63 ± 7 | 63 ± 7 | 63 ± 7 | 63 ± 7 | 0.0026 |
| Race-ethnicity [n (%)] | ||||||
| White | 114,808 (83.5) | 30,583 (89.0) | 29,623 (85.9) | 28,182 (82.4) | 26,420 (76.7) | <0.0001 |
| Black | 11,398 (8.3) | 1580 (4.6) | 2462 (7.1) | 3200 (9.4) | 4156 (12.1) | |
| Hispanic | 5250 (3.8) | 1248 (3.6) | 1222 (3.5) | 1297 (3.8) | 1483 (4.3) | |
| American Indian | 575 (0.4) | 141 (0.4) | 131 (0.4) | 158 (0.5) | 145 (0.4) | |
| Asian/Pacific Islander | 3558 (2.6) | 359 (1.0) | 624 (1.8) | 918 (2.7) | 1657 (4.8) | |
| Unknown | 1897 (1.4) | 434 (1.3) | 430 (1.2) | 458 (1.3) | 575 (1.7) | |
| Education, college degree, or higher [n (%)]3–5 | 54,807 (40.2) | 14,172 (41.6) | 13,706 (40.0) | 13,456 (39.6) | 13,473 (39.4) | <0.0001 |
| Parental fracture [n (%)]4–7 | 50,649 (36.8) | 13,058 (38.0) | 12,958 (37.6) | 12,514 (36.6) | 12,119 (35.2) | <0.0001 |
| Fracture on or after age 55 y [n (%)] | 17,614 (12.8) | 4472 (13.0) | 4498 (13.0) | 4359 (12.7) | 4285 (12.4) | 0.0109 |
| ≥Two falls in the past 12 mo [n (%)]5–7 | 16,626 (12.1) | 4306 (12.5) | 4324 (12.5) | 4149 (12.1) | 3847 (11.2) | <0.0001 |
| Treated diabetes [n (%)]3–7 | 5958 (4.3) | 1083 (3.2) | 1476 (4.3) | 1603 (4.7) | 1796 (5.2) | <0.0001 |
| Current HT user [n (%)]5–7 | 54,716 (39.8) | 13,768 (40.1) | 13,920 (40.4) | 13,655 (39.9) | 13,373 (38.8) | 0.0004 |
| Current smoker [n (%)] | 9425 (6.9) | 1928 (5.6) | 2197 (6.4) | 2439 (7.1) | 2861 (8.3) | <0.0001 |
| Arthritis [n (%)] | 65,168 (47.4) | 16,342 (47.6) | 16,477 (47.8) | 16,177 (47.3) | 16,172 (47.0) | 0.0953 |
| Very good to excellent general health [n (%)]3–68 | 79,730 (58.0) | 21,198 (61.7) | 20,025 (58.1) | 19,370 (56.6) | 19,137 (55.6) | <0.0001 |
| Depression (CES-D score) | 0.04 ± 0.13 | 0.04 ± 0.13 | 0.04 ± 0.13 | 0.04 ± 0.13 | 0.04 ± 0.13 | 0.3397 |
| BMI (kg/m2)3–68 | 27.8 ± 5.90 | 27.2 ± 5.62 | 27.9 ± 5.90 | 28.1 ± 6.03 | 28 ± 6.09 | <0.0001 |
| Physical activity (METs/wk)3–68 | 12.8 ± 13.93 | 14.3 ± 14.78 | 12.7 ± 13.59 | 12.1 ± 13.44 | 12.1 ± 13.75 | <0.0001 |
| Energy intake (kcal/d) | 1622 ± 633 | 1580 ± 587 | 1645 ± 629 | 1660 ± 657 | 1603 ± 653 | <0.0001 |
| Protein intake (g/d)3–578 | 68 ± 28.47 | 67 ± 27.76 | 70 ± 28.73 | 69 ± 29.09 | 65 ± 28.02 | <0.0001 |
| Fat intake (g/d) | 59 ± 32.13 | 47 ± 25.14 | 58 ± 29.53 | 64 ± 32.89 | 68 ± 35.85 | <0.0001 |
| Saturated fat | 20 ± 11.59 | 17 ± 9.92 | 20 ± 11.31 | 21 ± 12.18 | 21 ± 12.2 | <0.0001 |
| Monounsaturated fat | 22 ± 12.46 | 18 ± 9.84 | 22 ± 11.51 | 24 ± 12.75 | 26 ± 13.83 | <0.0001 |
| Polyunsaturated fat | 12 ± 6.89 | 9 ± 4.327 | 11 ± 5.333 | 13 ± 6.392 | 16 ± 8.51 | <0.0001 |
| n−6 FAs | 10.7 ± 6.16 | 7.6 ± 3.991 | 9.8 ± 4.86 | 11.5 ± 5.774 | 13.9 ± 7.624 | <0.0001 |
| n−3 FAs | 1.4 ± 0.764 | 0.8 ± 0.350 | 1.2 ± 0.47 | 1.5 ± 0.614 | 2.1 ± 0.901 | <0.0001 |
| ALA | 1.27 ± 0.72 | 0.75 ± 0.33 | 1.07 ± 0.45 | 1.37 ± 0.59 | 1.87 ± 0.87 | < 0.0001 |
| EPA + DHA | 0.13 ± 0.12 | 0.08 ± 0.07 | 0.12 ± 0.09 | 0.14 ± 0.12 | 0.17 ± 0.17 | <0.0001 |
| Calcium intake (mg/d)9 | 1199 ± 739.36 | 1358 ± 807.17 | 1235 ± 702.76 | 1155 ± 673.6 | 1048 ± 732.23 | <0.0001 |
| Vitamin D intake (IU/d)9 | 375 ± 280.55 | 407 ± 292.05 | 381 ± 281.72 | 368 ± 274.99 | 345 ± 269.32 | <0.0001 |
All variables were assessed at the baseline screening visit. Dietary variables were assessed with a food-frequency questionnaire. CES-D, Center for Epidemiologic Studies–Depression Scale; HT, hormone therapy; METs, metabolic equivalents; ALA, α-linolenic acid; EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid. P values for categorical variables, except race-ethnicity, were obtained by using chi-square tests for linear trend. The P value for race was obtained by using a chi-square test for association. P values for continuous variables were obtained by using general linear model t tests for slope. Differences between all quartiles were found for race-ethnicity, current smoker, general health, energy, fat, saturated fat, monounsaturated fat, polyunsaturated fat, n−6 fatty acid, n−3 fatty acid, ALA, EPA + DHA, calcium, and vitamin D intakes (P < 0.0001).
Mean ± SD (all such values).
Significant differences between Q1 and Q2, P < 0.0083.
Significant differences between Q1 and Q3, P < 0.0083.
Significant differences between Q1 and Q4, P < 0.0083.
Significant differences between Q2 and Q4, P < 0.0083.
Significant differences between Q3 and Q4, P < 0.0083.
Significant differences between Q2 and Q3, P < 0.0083.
Calcium and vitamin D values include the combined intake from food and supplements.