Colorectal cancer (CRC) is the third most common cancer in both sexes and the second in terms of mortality. Apart from genetic predisposition, dietary and lifestyle factors have been implicated in the development of CRC. Several studies suggested that vitamin D (VitD) might be a promising strategy in CRC prevention, while other studies did not confirm this finding. The aim of our study was to examine the role of Vit-D supplementation in the prevention of colorectal neoplasms (CRC and polyps). We conducted a systematic search in Pubmed, Embase and Web of Science databases for Randomized Controlled Trials (RCTs) examining the incidence of colorectal neoplasms in patients taking Vit-D supplementation compared to placebo. We synthetized results using Risk Ratio along with 95% Confidence Intervals (CIs). Nine RCTs (N = 71,386) were included. Non-significant correlations were observed between Vit-D supplementation and CRC incidence (RR:1.06, p = 0.52). Similarly, non-significant associations were observed between the use of Vit-D supplements and colorectal adenoma incidence (RR:1.00, p = 0.91). Advanced adenomas (OR:1.05, p = 0.63) and serrated polyps (RR:1.03, p = 0.63) were also not significantly inversely associated with Vit-D supplementation. Our study shows that Vit-D does not seem to have a role in the chemoprevention of colorectal neoplasms. However, additional well-designed studies are needed in order to draw safe conclusions. A potentially beneficial role of Vit-D supplementation in CRC primary prevention in individuals with severe vitamin D deficiency as well in the primary prevention of early-onset CRC, requires further investigation.

结直肠癌 (CRC) 在男女中是第三大最常见的癌症，在死亡率方面排名第二。除了遗传易感性外，饮食和生活方式因素也与 CRC 的发展有关。几项研究表明，维生素 D (Vit D) 可能是预防 CRC 的一种有前途的策略，而其他研究并未证实这一发现。我们研究的目的是检查 Vit-D 补充剂在预防结直肠肿瘤（CRC 和息肉）中的作用。我们在 Pubmed、Embase 和 Web of Science 数据库中对随机对照试验 (RCT) 进行了系统搜索，以检查与安慰剂相比服用 Vit-D 补充剂的患者结直肠肿瘤的发病率。我们使用风险比和 95% 置信区间 (CI) 综合结果。九项随机对照试验（N  = 71,386) 被包括在内。在补充 Vit-D 和 CRC 发病率之间观察到非显着相关性（RR：1.06，p  = 0.52）。同样，在使用 Vit-D 补充剂和结直肠腺瘤发病率之间观察到非显着关联（RR：1.00，p  = 0.91）。晚期腺瘤（OR：1.05，p = 0.63) 和锯齿状息肉 (RR:1.03, p = 0.63) 也与 Vit-D 补充没有显着负相关。我们的研究表明，Vit-D 似乎在结直肠肿瘤的化学预防中没有作用。然而，为了得出安全的结论，还需要额外的精心设计的研究。Vit-D 补充剂在严重维生素 D 缺乏症患者的 CRC 一级预防以及早发性 CRC 一级预防中的潜在有益作用需要进一步研究。