The researchers investigated the association between dietary intake of folic acid and colorectal cancer risk among a large cohort of women.
The findings of the study were reported in the International Journal of Cancer.
Folate is crucial for normal DNA methylation, synthesis and repair, and deficiency of this nutrient is hypothesized to lead to cancer through disruption of these processes.
There is some evidence to suggest that relatively high dietary folate intake might be associated with reduced colorectal cancer risk, especially among individuals with low methionine intake.
A cohort of 56,837 women, who were enrolled in the Canadian National Breast Screening Study, was studied.
Each completed a self-administered dietary questionnaire.
| Folate intake reduced colorectal cancer risk to 60% of that of the general population.
| International Journal of Cancer |
During follow-up to the end of 1993, a total of 389 women were diagnosed with colorectal cancer, identified by linkage to the Canadian Cancer Database.
For comparative purposes, a subcohort of 5681 women was randomly selected from the full dietary cohort at baseline.
After exclusions for various reasons, the analyses were based on 295 cases and 5334 non-cases.
The team found that folate intake was inversely associated with colorectal cancer risk (Relative risk = 0.6).
The inverse association was essentially similar among individuals with low and high methionine intake.
It was also similar for colon and rectal cancers when those endpoints were analyzed separately.
Among individuals with low methionine intake, folate intake did not appear to lower the risk of rectal cancer. This finding may be due, in part, to the low number of cases in the subgroup analysis.
Paul Terry, of the Albert Einstein College of Medicine, New York, USA, concluded on behalf of his colleagues, "Overall, our data lend some support to the hypothesis that high folate intake is associated with a reduced risk of colorectal cancer."