Folic Acid and Calcium May Provide Protection Against Colon Cancer
Folic acid and calcium are believed to have protective effects against colorectal cancer. They are thought to decrease cell proliferation and angiogenesis. The two compounds have also been shown to have protective effects against adenoma formation. However, a recent study found that supplementation with these nutrients did not have a significant inverse association with CRC.
The Nurses' Health Study is a large population-based cohort study with over 88 thousand female participants. In the trial, no inverse association was observed between supplementation and CRC risk during the first five years. As time progressed, however, a substantial reduction in the incidence of colon cancer was found. This result was confirmed in a larger cohort study (Cancer Prevention Study II).
A recent study by Giovanucci et al investigated the effect of folic acid on colorectal adenoma risk. They found that moderate dietary increases in folic acid intake prior to the development of premalignant lesions were associated with a decreased risk.
Researchers have suggested that the folic acid-CRC relationship may be affected by functional polymorphisms within the folate metabolic pathway. Specifically, there is a thymidylate synthase promoter variant that confers reduced thymidylate synthase enzyme function.
Folic acid supplementation has been linked to neoplastic foci in animal studies. However, this is difficult to determine in the general population. Furthermore, it is impossible to establish whether the observed associations are causal.
Because of these issues, additional studies are needed to clarify the effects of folic acid supplementation. There are also questions about how folic acid supplements are influenced by genotypes.