Article

Folate intake and risk of colorectal cancer and adenoma: modification by time

Department of Food and Nutrition, Sookmyung Women's University, Seoul, Republic of Korea.
American Journal of Clinical Nutrition (Impact Factor: 6.92). 03/2011; 93(4):817-25. DOI: 10.3945/ajcn.110.007781
Source: PubMed

ABSTRACT Experimental and observational studies have suggested that folate may play dual roles in colorectal cancer risk depending on the timing and dose.
We examined the latency between folate intake and the incidence of colorectal cancer.
We prospectively examined associations between folate intake assessed every 2 to 4 y by using validated food-frequency questionnaires and risk of colorectal cancer and adenoma in the Nurses' Health Study and Health Professionals Follow-Up Study, which included 2299 incident colorectal cancers and 5655 colorectal adenomas from 1980 to 2004.
There was an association between total folate intake 12-16 y before diagnosis and lower risk of colorectal cancer (relative risk: 0.69; 95% CI: 0.51, 0.94; ≥800 compared with <250 μg folate/d), but there was no association between intake in the recent past and colorectal cancer risk. Long- and short-term intakes of total folate were associated with a lower risk of colorectal adenoma, with a strong association with intake 4-8 y before diagnosis (odds ratio: 0.68; 95% CI: 0.60, 0.78; ≥800 compared with <250 μg folate/d). The current use of multivitamins for >15 y, but not a shorter duration of use, was associated with lower risk of colorectal cancer; and a shorter duration of use was related to lower risk of adenoma. We did not observe an adverse effect of total folate or synthetic folic acid on risk of colorectal cancer or adenoma even during the folic acid fortification era.
Folate intake is inversely associated with risk of colorectal cancer only during early preadenoma stages.

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Available from: Jing Ma, Aug 30, 2015
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    • "However, this finding might also suggest that the latency time between methionine intake and the clinical detection of CRC might serve as an effect modification of the association. Recent evidence from large prospective studies documents that total folate intake in the remote past (12-16 years before diagnosis), rather than close to diagnosis (0-8 years) was associated with reduced risk of CRC; furthermore, the investigators also found that intake close to diagnosis (0-8 years) was most strongly associated with lower risk of colorectal adenoma, indicating that folate intake may be beneficial only during early preadenoma stages [33]. Both methionine and folate are the key components of one carbon metabolism. "
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    ABSTRACT: Methionine is one of the key components of one carbon metabolism. Experimental studies indicate that methionine may reduce inflammation-induced colon cancer. However, epidemiologic findings as to whether dietary methionine intake influences colorectal cancer incidence in humans are inconsistent. To investigate the relationship between dietary methionine intake and risk of colorectal cancer by performing a meta-analysis of prospective studies. Eligible studies were identified by searching PubMed and Embase and by reviewing the bibliographies of the retrieved publications. The summary risk estimates were computed using both a random- effects and a fixed-effects model. Eight eligible prospective cohort studies involving 431,029 participants and 6,331 colorectal cancer cases were identified. According to the random-effects model, the summary relative risks (RRs) for the highest compared with the lowest intake of methionine were 0.89 (95% confidence interval [CI] = 0.77-1.03) for colorectal cancer, 0.77 (95% CI = 0.64 - 0.92) for colon cancer, and 0.88 (95% CI = 0.55-1.42) for rectal cancer. In the stratified analysis, a significant inverse association between dietary methionine intake and risk of colorectal cancer was observed in studies with longer follow-up time (RR=0.81, 95% CI= 0.70- 0.95), in Western studies (RR= 0.83, 95% CI = 0.73 - 0.95) and in men (RR = 0.75, 95% CI= 0.57-0.99). We found no indication of publication bias. This meta-analysis indicates that dietary methionine intake may be associated with decreased risk of colorectal cancer, especially colon cancer. More prospective studies with long follow-up time are needed to confirm these findings.
    PLoS ONE 12/2013; 8(12):e83588. DOI:10.1371/journal.pone.0083588 · 3.23 Impact Factor
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    • "Recently, a study that investigated 2299 incidents and 5655 CRA in Nurses' Health Study and Health Professionals Follow-Up Study showed that folic acid intake 12-16 y before diagnosis was inversely associated with CRC and identified the latency that folic acid should be provided. However, the study didn't analyze the results that folic acid was provided after diagnosis [22]. With the same kind of chemical in a rat model of CRC, folate deficiency was found to enhance the development of neoplasia compared to the diets containing 8 mg/kg folic acid [21] but the study had no related mechanisms. "
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    ABSTRACT: Whether Folic acid is a potential drug that may prevent the progression of colorectal carcinoma and when to use are important healthy issues we focus on. Our study is to examine the effect of folic acid on the development of the CRC and the optimal time folic acid should be provided in a mouse-ICR model induced by 1, 2-Dimethylhydrazine. Also, we investigated the gene expression profile of this model related to folic acid. Female ICR mouse (n=130) were divided into 7 groups either with the treatment of 1, 2-Dimethylhydrazine (20 mg/kg bodyweight) weekly or folic acid (8 mg/kg bodyweight) twice a week for 12 or 24 weeks. Using a 4 x 44 K Agilent whole genome oligo microarray assay, different gene expression among groups (NS, DMH, FA2, FA3) were identified and selected genes were validated by real-time polymerase chain reaction. Animals with a supplementary of folic acid showed a significant decrease in the incidence, the maximum diameter and multiplicity of adenocarcinomas (P<0.05). Furthermore, there were fewer adenomas or adenocarcinomas developed in the group of folic acid supplementation in pre-adenoma stage compared to group of post-adenoma stage. Meanwhile, about 1070 genes that were changed by 1, 2-Dimethylhydrazine can be reversed by folic acid and 172 differentially genes were identified between the groups of pre- and post- adenoma stage using microarray gene expression analysis. Our study demonstrated that folic acid supplementary was significantly associated with the decrease risk of CRC. And the subgroup of providing folic acid without precancerous lesions was more effective than that with precancerous lesions.
    Journal of Experimental & Clinical Cancer Research 12/2011; 30(1):116. DOI:10.1186/1756-9966-30-116 · 4.23 Impact Factor
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    • "Insufficient folate or vitamin B12 intake, genetic variation [1], or drug interference [2] can disrupt normal OCM function. OCM dysfunction is linked to severe health complications such as cancer [3], [4], anemia [5] and neural tube defects [6]. Folate-mediated OCM also influences levels of the non-protein amino acid, homocysteine. "
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    ABSTRACT: One-carbon metabolism (OCM) is linked to DNA synthesis and methylation, amino acid metabolism and cell proliferation. OCM dysfunction has been associated with increased risk for various diseases, including cancer and neural tube defects. MicroRNAs (miRNAs) are ∼ 22 nt RNA regulators that have been implicated in a wide array of basic cellular processes, such as differentiation and metabolism. Accordingly, mis-regulation of miRNA expression and/or activity can underlie complex disease etiology. We examined the possibility of OCM regulation by miRNAs. Using computational miRNA target prediction methods and Monte-Carlo based statistical analyses, we identified two candidate miRNA "master regulators" (miR-22 and miR-125) and one candidate pair of "master co-regulators" (miR-344-5p/484 and miR-488) that may influence the expression of a significant number of genes involved in OCM. Interestingly, miR-22 and miR-125 are significantly up-regulated in cells grown under low-folate conditions. In a complementary analysis, we identified 15 single nucleotide polymorphisms (SNPs) that are located within predicted miRNA target sites in OCM genes. We genotyped these 15 SNPs in a population of healthy individuals (age 18-28, n =  2,506) that was previously phenotyped for various serum metabolites related to OCM. Prior to correction for multiple testing, we detected significant associations between TCblR rs9426 and methylmalonic acid (p  =  0.045), total homocysteine levels (tHcy) (p  =  0.033), serum B12 (p < 0.0001), holo transcobalamin (p < 0.0001) and total transcobalamin (p < 0.0001); and between MTHFR rs1537514 and red blood cell folate (p < 0.0001). However, upon further genetic analysis, we determined that in each case, a linked missense SNP is the more likely causative variant. Nonetheless, our Monte-Carlo based in silico simulations suggest that miRNAs could play an important role in the regulation of OCM.
    PLoS ONE 07/2011; 6(7):e21851. DOI:10.1371/journal.pone.0021851 · 3.23 Impact Factor
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