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Meta-Analysis
, 14, 1326

Folate Intake, Serum Folate Levels, and Prostate Cancer Risk: A Meta-Analysis of Prospective Studies

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Meta-Analysis

Folate Intake, Serum Folate Levels, and Prostate Cancer Risk: A Meta-Analysis of Prospective Studies

Rong Wang et al. BMC Public Health.

Abstract

Background: Studies have reported inconsistent results concerning the existence of associations of folate intake and serum folate levels with prostate cancer risk. This study sought to summarise the evidence regarding these relationships using a dose-response meta-analysis approach.

Methods: In January 2014, we performed electronic searches of PubMed, Embase, and the Cochrane Library to identify studies examining the effect of folate on the incidence of prostate cancer. Only prospective studies that reported effect estimates with 95% confidence intervals (CIs) of the incidence of prostate cancer for more than 2 categories of folate were included.

Results: Overall, we included 10 prospective studies reporting data on 202,517 individuals. High dietary folate intake had little or no effect on prostate cancer risk (risk ratio [RR] = 1.02; 95% CI = 0.95-1.09; P = 0.598). The dose-response meta-analysis suggested that a 100 μg per day increase in dietary folate intake has no significant effect on the risk of prostate cancer (RR = 1.01; 95% CI = 0.99-1.02; P = 0.433). However, high serum folate levels were associated with an increased risk of prostate cancer (RR = 1.21; 95% CI = 1.05-1.39; P = 0.008). The dose-response meta-analysis indicated that a 5 nmol/L increment of serum folate levels was also associated with an increased risk of prostate cancer (RR = 1.04; 95% CI = 1.00-1.07; P = 0.042).

Conclusions: Our study indicated that dietary folate intake had little or no effect on prostate cancer risk. However, increased serum folate levels have potentially harmful effects on the risk of prostate cancer.

Figures

Figure 1
Figure 1
Flow diagram of the literature search and studies selection process.
Figure 2
Figure 2
Relative risk estimates of prostate cancer for high versus low dietary folate intake (A) and per 100 ug/day increment in folate intake for prostate cancer (B).
Figure 3
Figure 3
Dose-response relations for dietary folate intake (A) and serum folate levels (B).
Figure 4
Figure 4
Relative risk estimates of prostate cancer for high versus low serum folate levels (A) and per 5 nmol/L increment in serum folate levels for prostate cancer (B).
Figure 5
Figure 5
Funnel plot for per 100 ug/day increment in dietary folate intake (A) and per 5 nmol/L increment in serum folate levels for prostate cancer (B).

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Pre-publication history
    1. The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2458/14/1326/prepub

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