CRC is one of the most threatening tumors, comprising 10.2% of all diagnosed tumors and 9.2% of cancer-related mortality worldwide [1]. In 2018, it was ranked the third malignancy in incidence, and the second malignancy in mortality related to cancer [2]. The CRC rates are expected to increase [2] despite the screening programs [3]. Vit-B9 (folic acid; FA) is a water-soluble vitamin that plays a significant role in de novo synthesis of purines and thymidine as well as its essential role in preventing several disorders such as megaloblastic anemia, atherosclerosis, neural tube defects and cancer [4]. Herein, we aim to clarify the relationship between folic acid and CRC.