Table 1.
Relationships between soy isoflavone intake and some variables relevant to isoflavone intake and reproduction in the Adventist Health study-2
| Soy isoflavone intake (mg per day)
|
P for trend | ||||||
|---|---|---|---|---|---|---|---|
| 0–9 | 10–19 | 20–29 | 30–39 | 40–49 | ≥50 | ||
| Number of women | 6,089 | 1,968 | 1,376 | 812 | 529 | 914 | – |
| Isoflavone intake (mg/day) | 3.7 (2.9) | 14.7 (3.1) | 24.6 (2.9) | 34.5 (2.9) | 44.8 (2.9) | 79.3 (32.5) | – |
| Age at enrollment | 42.0 (5.3) | 42.1 (5.3) | 41.9 (5.4) | 42.0 (5.4) | 41.8 (5.3) | 41.6 (5.6) | 0.04 |
| % never married | 13.1 (798) | 10.9 (215) | 11.9 (164) | 10.3 (84) | 11.5 (61) | 14.2 (130) | 0.6 |
| % with college | 46.5 (2,833) | 54.5 (1,072) | 56.8 (781) | 55.4 (450) | 56.3 (298) | 59.2 (541) | <0.001 |
| % Black | 35.3 (2,134) | 32.8 (640) | 29.5 (402) | 28.0 (226) | 33.9 (178) | 37.4 (338) | 0.2 |
| Age at menarche | 12.41 (1.54) | 12.37 (1.49) | 12.39 (1.51) | 12.49 (1.52) | 12.46 (1.51) | 12.40 (1.53) | 0.6 |
| % used OCs | 77.3 (4,694) | 76.6 (1,502) | 74.8 (1,023) | 70.7 (571) | 69.8 (368) | 65.9 (599) | <0.001 |
| % extended OC use* | 3.4 (206) | 2.0 (39) | 1.5 (20) | 1.6 (13) | 1.1 (6) | 1.0 (9) | <0.001 |
| % never pregnant | 17.9 (1,089) | 19.6 (385) | 18.8 (258) | 20.3 (165) | 19.1 (101) | 22.3 (204) | 0.002 |
| % nulliparous | 24.7 (1,506) | 25.7 (506) | 25.9 (357) | 26.5 (215) | 26.1 (138) | 29.7 (271) | 0.003 |
| % problems becoming pregnant | 17.1 (1,032) | 16.1 (315) | 17.8 (243) | 16.4 (132) | 15.7 (82) | 15.6 (141) | 0.3 |
| Parity in all women | 1.69 (1.27) | 1.67 (1.29) | 1.60 (1.21) | 1.67 (1.31) | 1.61 (1.25) | 1.54 (1.27) | <0.001 |
| Parity in parous women | 2.24 (0.95) | 2.24 (0.97) | 2.17 (0.87) | 2.27 (0.97) | 2.18 (0.95) | 2.19 (0.93) | 0.09 |
| Age at first delivery | 25.7 (5.2) | 26.3 (4.9) | 26.5 (5.0) | 26.5 (5.0) | 26.8 (5.2) | 27.0 (5.3) | <0.001 |
| % ever smoked | 7.0 (426) | 4.6 (91) | 4.7 (65) | 3.7 (30) | 4.9 (26) | 4.3 (39) | <0.001 |
| % ever used alcohol | 38.4 (2,327) | 27.1 (533) | 27.6 (379) | 26.6 (216) | 28.0 (148) | 25.9 (235) | <0.001 |
| Physical activity (times/week) | 2.2 (1.9) | 2.4 (1.9) | 2.5 (1.9) | 2.7 (1.9) | 2.6 (1.9) | 2.6 (1.9) | <0.001 |
| BMI (kg/m2) at age 20 | 21.6 (3.8) | 21.3 (3.4) | 21.4 (3.6) | 21.3 (3.7) | 21.3 (3.7) | 21.4 (4.1) | 0.002 |
| % with monthly use of caffeinated drinks | 49.3 (2,956) | 32.8 (633) | 27.6 (375) | 21.7 (173) | 19.8 (102) | 17.5 (157) | <0.001 |
| % vegetarians | 37.6 (2,292) | 63.6 (1,252) | 71.6 (985) | 77.7 (631) | 76.6 (405) | 76.5 (699) | <0.001 |
| % vegans | 2.1 (125) | 7.0 (137) | 10.7 (147) | 15.4 (125) | 17.8 (94) | 18.7 (171) | <0.001 |
| Vegetarian meat analogs (g/day) | 37 (38) | 62 (56) | 66 (64) | 66 (58) | 69 (73) | 81 (81) | <0.001 |
| Tofu/soybean products (g/day) | 3 (4) | 12 (12) | 24 (19) | 38 (23) | 49 (30) | 91 (74) | <0.001 |
| Soy milk (g/day) | 9 (29) | 74 (79) | 120 (112) | 153 (139) | 210 (171) | 380 (333) | <0.001 |
| Energy intake (kcal per day) | 1,736 (702) | 1,890 (689) | 1,980 (687) | 2,090 (702) | 2,267 (721) | 2,506 (788) | <0.001 |
Notes:
*
Used OCs for 7 or more years both when aged 20–29 years and when aged 30–39 years. Data given as percentages (n) or mean (SD)Abbreviations: SD, standard deviation; OC, oral contraceptives; BMI, body mass index.