Several case–control and prospective cohort studies have examined the association between the consumption of nuts and legumes and the risk of colorectal cancer. For the quantitative assessment of this association, we conducted a meta-analysis of observational studies. We searched PubMed and Web of Science databases along with hand searches for eligible studies published up to January 2022. A total of 13 studies (8 cohort studies and 5 case–control studies) on nuts consumption and 29 studies (16 cohort studies and 13 case–control studies) on legumes consumption were included in the meta-analysis. The pooled relative risks (RRs) of colorectal cancer for the highest versus lowest categories of nuts consumption and legumes consumption were 0.84 (95% CI: 0.71–0.99) and 0.90 (95% CI: 0.83–0.98), respectively. Based on the dose–response analysis, a 28 g/day (1 serving/day) increment of nut consumption was associated with a 33% lower risk of colorectal cancer, and 100 g/day (1 serving/day) increment of legumes consumption was associated with a 21% lower risk of colorectal cancer. By geographic region for nuts consumption, however, the inverse association for the highest versus lowest categories was only observed in Asia (RR = 0.44; 95% CI: 0.29–0.68) from 3 studies, and no association was found in America (RR = 1.01; 95% CI: 0.92–1.11) (P_difference = 0.003) or Europe (RR = 1.02; 95% CI: 0.84–1.25) (P_difference = 0.003). In addition, the associations tended to be weak when stratified by adjustment for confounders. Our findings suggest that the evidence for an association is currently weak, and thus further well-designed prospective studies are needed.

几项病例对照和前瞻性队列研究检查了坚果和豆类的食用与结直肠癌风险之间的关系。对于这种关联的定量评估，我们对观察性研究进行了荟萃分析。我们搜索了 PubMed 和 Web of Science 数据库，并手动搜索了截至 2022 年 1 月发表的符合条件的研究。共有 13 项关于坚果消费的研究（8 项队列研究和 5 项病例对照研究）和 29 项研究（16 项队列研究和 13 项案例研究） ——对照研究）豆类消费被纳入荟萃分析。最高和最低类别的坚果消费和豆类消费的结直肠癌汇总相对风险 (RR) 分别为 0.84 (95% CI: 0.71–0.99) 和 0.90 (95% CI: 0.83–0.98)。基于剂量反应分析，每天增加 28 克（1 份/天）的坚果摄入量与降低 33% 的结直肠癌风险相关，每天增加 100 克（1 份/天）的豆类摄入量与降低 21% 的风险相关结直肠癌。然而，从坚果消费的地理区域来看，仅在亚洲（RR = 0.44；95% CI：0.29-0.68）观察到最高与最低类别的负相关，来自 3 项研究，而在美国未发现相关性（RR = 1.01；95% CI：0.92–1.11) (P_差异 = 0.003）或欧洲（RR = 1.02；95% CI：0.84–1.25）（P_差异 = 0.003）。此外，通过调整混杂因素进行分层时，这些关联往往较弱。我们的研究结果表明，目前关联的证据很薄弱，因此需要进一步精心设计的前瞻性研究。