Dietary intake of vitamins A, C, and E and the risk of colorectal adenoma

ArticleinEuropean journal of cancer prevention: the official journal of the European Cancer Prevention Organisation (ECP) 22(6):529-39 · November 2013with17 Reads
DOI: 10.1097/CEJ.0b013e328364f1eb · Source: PubMed
Abstract
To comprehensively summarize the association between dietary intake of vitamins A, C, and E and the risk of colorectal adenoma (CRA), the precursor of colorectal cancer, relevant studies were identified in MEDLINE and EMBASE up to 31 October 2012. Summary relative risks (SRRs) with 95% confidence intervals (CIs) were pooled with a random-effects model. Between-study heterogeneity was assessed using Cochran's Q and I statistics. A total of 13 studies with 3832 CRA cases were included in this meta-analysis. On the basis of the highest versus lowest analysis, dietary intake of vitamin C reduced the risk of CRA by 22% (SRRs 0.78, 95% CIs: 0.62-0.98). Subgroup analyses showed that this relation was not modified by BMI, smoking status, and dietary energy intake. Further, dietary intake of β-carotene was also inversely associated with the risk of CRA. However, dietary intake of vitamins A and E was not associated with the risk of CRA in overall and subgroup analyses (vitamin A: SRRs 0.87, 95% CIs: 0.67-1.14; vitamin E: SRRs 0.87, 95% CIs: 0.69-1.10). Our results indicate that dietary intake of vitamin C and β-carotene, but not vitamins A and E, could reduce the risk of CRA. However, these associations seem to be limited. Further investigation using large samples and a rigorous methodology is warranted.
    • "Colditz et al. [30] proposed that study design, quality of implementation , exposure, and covariates contribute to heterogeneity in SR. Since meta-analysis in nutritional epidemiology uses both cohort and case-control studies, there is heterogeneity by study design [31,32]. Therefore, while NOS evaluation within a group with the same study design would be meaningful , subgroup analysis only with the NOS while ignoring differences in study design may compromise the results. "
    [Show abstract] [Hide abstract] ABSTRACT: Objectives: It is important to control quality level of selected studies, when conducting meta-analysis of observational studies. The Newcastle-Ottawa Scale (NOS) is a representative tool. We investigated the relationship between high quality (HQ) decision made with NOS and results of subgroup analysis by study design. Methods: We selected systematic review studies with meta-analysis which performed a quality evaluation on observational studies of diet and cancer by NOS. The HQ decision results and the distribution of study design were examined. The results of subgroup analysis by the quality level defined by NOS were extracted. Equivalence was evaluated on the summary effect size (sES) and the 95% confidence intervals computed in the subgroup analysis. Results: The meta-analysis results of the HQ group and the cohort group were identical. Overall sES, which was obtained by combining the sES when equivalence was observed between the cohort group and the case-control group, also showed equivalence. Conclusions: It is more reasonable to control quality level by performing subgroup analysis by study design rather than by HQ categorized by NOS quality assessment tool.
    Full-text · Article · Apr 2016
    • "Studies carried out to assess the association between carotenoid intake from natural sources and CRC reported inconsistent findings (Slattery et al., 2000; Malila et al., 2002; Terry et al., 2002; Chiu et al., 2003; McCullough et al., 2003; Satia-Abouta et al., 2003; Murtaugh et al., 2004; Nkondjock and Ghadirian, 2004; Paiva et al., 2004; Ravasco et al., 2005; Kune and Watson, 2006; Levy et al., 2006; Shin et al., 2006; Wakai et al., 2007; Chaiter et al., 2009; Park et al., 2009; Roswall et al., 2010; Williams et al., 2010; Banque et al., 2012; Wang et al., 2012; Leenders et al., 2014; Lu et al., 2015). A recently published meta-analysis of observational studies (12 case–control studies and one nested case–control study) reported dietary intake of β-carotene to be associated inversely with the risk for development of colorectal adenomas (CRAs) (Xu et al., 2013). As CRAs are recognized to be a precursor lesion for CRC, it could be the case that β-carotene could prevent CRC occurrence by preventing the development of CRAs. "
    [Show abstract] [Hide abstract] ABSTRACT: Carotenoid intake from natural sources has been hypothesized to reduce the risk of colorectal cancer (CRC). The aim of this study was to systematically review the epidemiological evidence for the association between carotenoid intake from natural sources and CRC development. We carried out a systematic review and meta-analysis of epidemiological studies to investigate whether the intake of specific carotenoids from natural sources, as well as combined carotenoids, is associated with the risk of CRC overall and by anatomic subsite. A comprehensive literature search of MEDLINE and Scopus databases was performed. Twenty-two articles were identified from the literature search, of which 16 were case-control studies and 6 were cohort studies. In the random-effects meta-analysis of case-control and cohort studies, we found no association between the intake of individual and total carotenoids and the risk of CRC overall and by anatomic subsite. Overall, our findings do not support a significant association between intake of specific carotenoids from dietary sources, as well as combined carotenoids, and the risk of CRC overall and by anatomic subsite. Copyright
    Full-text · Article · Mar 2016
    • "In addition to their anti-tumor effects it is possible that some carotenoids might exert procarcinogenic effects. Vitamin A and β-carotene had been reported associated with some cancers39404142. A recent study had reported that highest category of dietary vegetables and fruits intake could reduce lung cancer risk [43]. "
    [Show abstract] [Hide abstract] ABSTRACT: Whether dietary β-carotene and vitamin A intake protect against lung cancer risk is not clear. Therefore, we performed this meta-analysis to investigate the association between them. The related articles were searched using the databases PubMed and the Web of Knowledge up to May 2015. We used the random-effect model to estimate the relative risk (RR) and their 95% CI. Small-study effect was assessed using Egger's test. In total, 19 studies comprising 10,261 lung cancer cases met the inclusion criteria. The pooled RR and their 95% CI was 0.855 (0.739-0.989) for higher category of dietary vitamin A intake and lung cancer risk, especially among Asian populations and in the cohort studies. Evidence from 18 studies suggested that higher category of dietary β-carotene intake could reduce lung cancer risk (0.768 (0.675-0.874)).The associations were also significant in American and Asian populations. In conclusions, higher category of dietary β-carotene and vitamin A intakes could reduce the risk of lung cancer. However, the dose-response analysis was not performed due to the limited data in each individual study. Due to this limitation, further studies with detailed dose, cases and person-years for β-carotene and vitamin A of each category are wanted to assess this dose-response association.
    Full-text · Article · Nov 2015
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