Table 1.
Meta-analysis of pooled ORs (95% CI) of the highest versus lowest category and all combined higher versus the lowest category of dietary nitrate and nitrite consumption for selected, site-specific cancers.
| Type of Cancer | Highest versus the Lowest (Reference) Category | All Combined Highest versus the Lowest (Reference) Category | Publication Bias | |||
|---|---|---|---|---|---|---|
| Pooled OR (95% CI) | I-Squared (I2) and p-Value | Pooled OR (95% CI) | I-Squared (I2) and p-Value | Egger’s Test p-Value |
Begg’s Test p-Value |
|
| (a) Ovarian and uterine corpus (nitrate) | 1.03, (0.84, 1.22) | 28.7%, p = 0.240 | 0.97, (0.75, 1.19) | 80.6%, p = 0.001 | 0.067 | 0.090 |
| (b) Breast (nitrate) | 0.91, (0.81, 1.00) | 0.0%, p = 0.526 | 0.92, (0.87, 0.96) | 42.7%, p = 0.175 | 0.310 | 0.144 |
| (c) Thyroid (nitrate) | 1.40, (1.02, 1.77) | 0.0%, p = 0.706 | 1.27, (0.85, 1.69) | 62.0%, p = 0.072 | 0.064 | 0.325 |
| (d) Glioma (nitrate) | 1.11, (0.91, 1.31) | 0.0%, p = 0.546 | 1.11, (0.94, 1.29) | 66.9%, p = 0.049 | 0.132 | 0.040 |
| (e) Glioma (nitrite) | 1.17, (0.98, 1.37) | 0.0%, p = 0.646 | 1.12, (1.03, 1.22) | 0.0%, p = 0.661 | 0.442 | 0.060 |
| (f) Non-Hodgkin’s Lymphoma (nitrate) | 0.82, (0.69, 0.94) | 27.1%, p = 0.195 | 0.83, (0.75, 0.91) | 35.6%, p = 0.124 | 0.163 | 0.728 |
| (g) Non-Hodgkin’s Lymphoma (nitrite) | 1.21, (0.78, 1.64) | 63%, p = 0.019 | 1.11, (0.85, 1.38) | 71.4%, p = 0.004 | 0.496 | 0.702 |
| (h) Pancreatic (nitrate) | 0.96, (0.84, 1.09) | 35.9%, p = 0.167 | 0.95, (0.89, 1.00) | 48.0%, p = 0.087 | 0.722 | 0.399 |
| (i) Pancreatic (nitrite) | 0.87, (0.76, 0.97) | 44.3%, p = 0.095 | 1.04, (0.85, 1.24) | 76.1%, p = 0.000 | 0.000 | 0.000 |
| (j) Bladder (nitrate) | 0.94, (0.84, 1.04) | 0.0%, p = 0.615 | 0.94, (0.84, 1.03) | 70.7%, p = 0.001 | 0.089 | 0.322 |
| (k) Bladder (nitrite) | 1.07, (0.94, 1.19) | 0.0%, p = 0.574 | 1.05, (0.92, 1.18) | 79.2%, p = 0.000 | 0.045 | 0.338 |
| (l) Kidney (nitrate) | 0.79, (0.17, 1.41) | 64.7%, p = 0.059 | 0.84, (0.52, 1.16) | 73.1%, p = 0.024 | 0.019 | 0.016 |
| (m) Kidney (nitrite) | 0.92, (0.62, 1.23) | 0.0%, p = 0.586 | 1.10, (0.78, 1.48) | 76.7%, p = 0.014 | 0.322 | 0.245 |
| (n) Colon (nitrate) | 0.99, (0.91, 1.08) | 40.1%, p = 0.100 | 1.00, (0.96, 1.04) | 0.0%, p = 0.593 | 0.332 | 0.284 |
| (o) Colon (nitrite) | 1.02, (0.92, 1.11) | 44.8%, p = 0.093 | 1.02, (0.93, 1.11) | 67.2%, p = 0.006 | 0.027 | 0.141 |
| (p) Rectal (nitrate) | 1.01, (0.88, 1.14) | 33.4%, p = 0.161 | 1.10, (0.96, 1.24) | 68.8%, p = 0.002 | 0.367 | 0.930 |
| (q) Rectal (nitrite) | 1.09, (0.79, 1.39) | 68.2%, p = 0.008 | 1.06, (0.87, 1.26) | 82.3%, p = 0.000 | 0.841 | 0.952 |
| (r) Esophageal (nitrate) | 0.75, (0.57, 0.94) | 46.1%, p = 0.073 | 0.83, (0.72, 0.94) | 33.7%, p = 0.159 | 0.983 | 0.446 |
| (s) Esophageal (nitrite) | 1.01, (0.78, 1.23) | 0.0%, p = 0.689 | 0.93, (0.81, 1.05) | 0.0%, p = 0.881 | 0.197 | 0.714 |
| (t) Stomach (nitrate) | 0.81, (0.70, 0.92) | 0.0%, p = 0.776 | 0.81, (0.75, 0.87) | 22.0%, p = 0.234 | 0.000 | 0.006 |
| (u) Stomach (nitrite) | 1.06, (0.92, 1.20) | 32.9%, p = 0.127 | 1.04, (0.91, 1.11) | 54.7%, p = 0.012 | 0.308 | 0.382 |
I-squared (I2), a statistic representing the amount of total variation attributed to heterogeneity; p-value of Cochran’s Q test for heterogeneity.