Table 1. Subgroup analyses of nut consumption and cancer risk.
| Number of studies | Results | Heterogeneity | ||||
| RR | 95%CI | P value | I2 (%) | P value | ||
| All | 38 | 0.90 | (0.86-0.94) | <0.001 | 77.9 | <0.001 |
| Subgroup | ||||||
| Study design | ||||||
| Cohort | 22 | 0.93 | (0.89-0.97) | 0.001 | 74.9 | <0.001 |
| Case-control | 16 | 0.84 | (0.74-0.96) | 0.012 | 77.5 | <0.001 |
| Gender | ||||||
| Female | 16 | 0.87 | (0.79-0.95) | 0.001 | 81.8 | <0.001 |
| Male | 11 | 0.92 | (0.84-1.01) | 0.08 | 73.1 | <0.001 |
| Socioeconomic status | ||||||
| Developed country | 28 | 0.90 | (0.86-0.94) | <0.001 | 80.5 | <0.001 |
| Developing country | 10 | 0.90 | (0.72-1.13) | 0.365 | 42 | 0.111 |
| Cancer type | ||||||
| Breast cancer | 6 | 0.90 | (0.80-1.01) | 0.067 | 85 | <0.001 |
| Esophagus cancer | 3 | 0.97 | (0.88-1.06) | 0.498 | 0 | 0.427 |
| Gastric cancer | 5 | 0.83 | (0.71-0.97) | 0.017 | 54.4 | 0.067 |
| Colorectal cancer | 5 | 0.77 | (0.63-0.94) | 0.011 | 88.2 | <0.001 |
| Prostate cancer | 6 | 1.03 | (0.99-1.07) | 0.139 | 2.2 | 0.402 |
| Pancreatic cancer | 3 | 0.89 | (0.81-0.98) | 0.015 | 31.3 | 0.231 |
| Lung cancer | 3 | 0.89 | (0.87-0.92) | <0.001 | 0 | 0.369 |
| Ovarian cancer | 3 | 0.94 | (0.73-1.21) | 0.61 | 75.5 | 0.017 |
| Endometrial cancer | 1 | 0.87 | (0.63-1.20) | 0.391 | - | - |
| Liver cancer | 3 | 0.93 | (0.50-1.71) | 0.808 | 57.3 | 0.096 |
| Nuts type | ||||||
| Peanut | 13 | 0.94 | (0.84-1.04) | 0.225 | 67.4 | <0.001 |
| Tree nut | 8 | 0.88 | (0.79-0.99) | 0.03 | 57.5 | 0.021 |
| Peanut butter | 7 | 1.06 | (0.99-1.13) | 0.081 | 0 | 0.499 |
Abbreviations: RR, relative risk; CI, confidence interval.