Table 2.
Dietary intake of nitrate and nitrite (quintiles) and breast cancer risk
| Q1 (reference) | Q2 | Q3 | Q4 | Q5 | ptrend | |
|---|---|---|---|---|---|---|
| Nitrate | ||||||
| Median (mg/d) | 49.3 | 78.7 | 106.1 | 140.2 | 209.9 | |
| Range (mg/d) | 3.9 – 65.2 | 65.2 – 91.8 | 91.8 – 121.8 | 121.8 – 165.6 | 165.6 – 2,346.4 | |
| Cases | 604 | 541 | 575 | 601 | 554 | |
| Person-years | 123,277 | 125,273 | 124,907 | 125,466 | 124,333 | |
| HR (95%CI)a | 1.0 | 0.86 (0.76 – 0.98) | 0.90 (0.79 – 1.02) | 0.96 (0.84 – 1.10) | 0.86 (0.74 – 1.01) | 0.31 |
| Nitrite | ||||||
| Median (mg/d) | 0.6 | 0.9 | 1.1 | 1.4 | 1.8 | |
| Range (mg/d) | 0.1 – 0.8 | 0.8 – 1.0 | 1.0 – 1.2 | 1.2 – 1.5 | 1.5 – 7.1 | |
| Cases | 532 | 604 | 573 | 589 | 577 | |
| Person-years | 123,423 | 124,696 | 124,948 | 124,903 | 125,284 | |
| HR (95%CI)a | 1.0 | 1.12 (0.98 – 1.28) | 1.06 (0.92 – 1.22) | 1.10 (0.94 – 1.28) | 1.05 (0.86 – 1.29) | 0.28 |
| Nitrate-folate ratio | ||||||
| Median | 0.12 | 0.22 | 0.31 | 0.40 | 0.57 | |
| Range | 0.01 – 0.17 | 0.17 – 0.26 | 0.26 – 0.35 | 0.35 – 0.47 | 0.47 – 2.66 | |
| Cases | 569 | 575 | 608 | 560 | 563 | |
| Person-years | 122,949 | 124,816 | 124,405 | 126,670 | 124,415 | |
| HR (95%CI)a | 1.0 | 0.96 (0.84 – 1.10) | 0.98 (0.84 – 1.14) | 0.87 (0.75 – 1.02) | 0.87 (0.74 – 1.03) | 0.04 |
a
Adjusted for age (continuous), total energy intake (continuous), BMI (continuous), WHR (continuous), education (<high school, high school, >high school), smoking (never, previous, current), physical activity level (low, moderate, high), alcohol intake (yes, no), family history of breast cancer (yes/no), age at menopause (continuous), age at first live birth (<20, 20 – <30, ≥30, nulliparous), estrogen use (never, ever), total intake of folate (except for nitrate-folate ratio), vitamin C and E and flavonoids, intakes of cruciferae and red meat.