TABLE 5.
Percentage differences (95% CIs) in concentrations of plasma biomarkers of sex hormones according to decaffeinated coffee consumption among participants from the Nurses’ Health Study and the Health Professionals Follow-Up Study1
| Categories of decaffeinated coffee consumption | ||||||
|---|---|---|---|---|---|---|
| Variable | Nondrinker | ≤1 cup/d | 2 cups/d | ≥3 cups/d | Per cup increase | P-trend |
| Estrone | ||||||
| n | 1267 | 1414 | 468 | 511 | ||
| Model 1 | 0 (ref) | 1.4 (−2.5, 5.4) | 2.3 (−3.1, 8.0) | −5.4 (−10.3, −0.2) | −1.4 (−2.9, 0.2) | 0.08 |
| Model 2 | 0 (ref) | 1.0 (−2.6, 4.6) | 2.2 (−2.8, 7.4) | −5.5 (−10.1, −0.8) | −1.5 (−2.9, −0.1) | 0.04 |
| Total estradiol | ||||||
| n | 1499 | 1694 | 538 | 598 | ||
| Model 1 | 0 (ref) | 0.7 (−2.9, 4.5) | −5.1 (−9.9, 0.1) | −9.4 (−14.0, −4.6) | −3.3 (−4.8, −1.9) | <0.001 |
| Model 2 | 0 (ref) | 1.1 (−2.2, 4.6) | −3.6 (−8.1, 1.1) | −7.8 (−12.0, −3.4) | −2.8 (−4.1, −1.4) | <0.001 |
| Free estradiol | ||||||
| n | 1175 | 1339 | 413 | 462 | ||
| Model 1 | 0 (ref) | −2.1 (−6.6, 2.6) | −7.3 (−13.3, −0.8) | −12.5 (−18.1, −6.6) | −4.2 (−6.0, −2.3) | <0.001 |
| Model 2 | 0 (ref) | −1.1 (−5.2, 3.2) | −4.9 (−10.4, 1.0) | −11.0 (−16.1, −5.5) | −3.4 (−5.1, −1.7) | <0.001 |
| SHBG | ||||||
| n | 2009 | 2348 | 716 | 842 | ||
| Model 1 | 0 (ref) | 5.7 (2.3, 9.2) | 5.9 (1.1, 10.9) | 8.4 (3.7, 13.4) | 2.2 (0.9, 3.5) | 0.001 |
| Model 2 | 0 (ref) | 2.1 (−0.7, 5.0) | 3.3 (−0.7, 7.6) | 5.8 (1.8, 10.0) | 1.6 (0.4, 2.7) | 0.01 |
| Total testosterone (women) | ||||||
| n | 1659 | 2030 | 677 | 818 | ||
| Model 1 | 0 (ref) | −0.9 (−4.1, 2.4) | 1.4 (−3.1, 6.2) | −0.8 (−5.0, 3.7) | 0.1 (−1.1, 1.4) | 0.84 |
| Model 2 | 0 (ref) | 0.5 (−2.8, 3.9) | 2.3 (−2.3, 7.1) | −0.7 (−5.0, 3.7) | −0.1 (−1.4, 1.2) | 0.86 |
| Free testosterone (women) | ||||||
| n | 1208 | 1513 | 492 | 593 | ||
| Model 1 | 0 (ref) | −5.1 (−9.8, −0.2) | −0.04 (−6.8, 7.2) | −4.7 (−10.9, 2.0) | −0.6 (−2.5, 1.3) | 0.55 |
| Model 2 | 0 (ref) | 0.9 (−3.6, 5.7) | 3.7 (−2.7, 10.5) | −0.4 (−6.4, 5.9) | 0.1 (−1.6, 1.9) | 0.90 |
| Total testosterone (men) | ||||||
| n | 572 | 604 | 147 | 156 | ||
| Model 1 | 0 (ref) | 1.3 (−2.9, 5.7) | 6.0 (−0.9, 13.5) | 5.1 (−1.6, 12.4) | 1.4 (−0.5, 3.4) | 0.15 |
| Model 2 | 0 (ref) | 2.5 (−1.7, 6.8) | 6.0 (−0.6, 13.1) | 8.4 (1.6, 15.7) | 2.1 (0.2, 4.0) | 0.03 |
| Free testosterone (men) | ||||||
| n | 561 | 595 | 145 | 152 | ||
| Model 1 | 0 (ref) | 1.1 (−3.1, 5.5) | 5.2 (−1.6, 12.5) | 5.9 (−0.9, 13.2) | 1.2 (−0.7, 3.2) | 0.21 |
| Model 2 | 0 (ref) | 1.7 (−2.5, 6.1) | 4.7 (−1.9, 11.8) | 7.9 (1.0, 15.2) | 1.6 (−0.3, 3.6) | 0.10 |
Model 1 was adjusted for sex and age at blood draw (linear and quadratic terms). Model 2 was additionally adjusted for race (white, nonwhite), fasting status (yes or no), cumulative average levels of BMI (in kg/m2; <23.0, 23.0–24.9, 25.0–27.4, 27.5–29.9, or ≥30.0), physical activity (<3.0, 3.0–8.9, 9.0–17.9, 18.0–26.9, or ≥27.0 metabolic equivalent of task-h/wk), alcohol consumption (0, 0.1–4.9, 5.0–9.9, 10.0–14.9, or ≥15.0 g/d), smoking (never; past: <30; past: ≥30; current: <30; or current: ≥30 pack-years), Alternative Healthy Eating Index dietary score (quintiles), total energy intake (quintiles), caffeine intake (quintiles) calculated from dietary items except coffee (tea, cola beverage, and chocolate), regular multivitamin use (yes or no), regular aspirin or nonsteroidal anti-inflammatory drug use (yes or no), hypertension (yes or no), hypercholesterolemia (yes or no), and for women, menopausal status (premenopausal, postmenopausal, or unknown) and menopausal hormone therapy (never, past, or current use). For the analysis of caffeinated and decaffeinated coffee, mutual adjustment was performed. ref, reference; SHBG, sex hormone–binding globulin.