Previous studies regarding the association between carrot intake and prostate cancer risk have reported inconsistent results. We conducted a meta-analysis to summarize evidence on this association and to quantify the potential dose–response relationship.
A systematic literature search of papers published in August 2013 was conducted using PubMed, EMBASE, Scopus, Web of Science, the Cochrane register, and the Chinese National Knowledge Infrastructure databases, and the references of the retrieved articles were screened. The summary risk estimates with 95 % confidence intervals (CIs) for the highest versus the lowest intake of carrots were calculated. A dose–response meta-analysis was also conducted for the studies reporting categorical risk estimates for a series of exposure levels.
We found a significantly decreased risk of prostate cancer associated with the intake of carrots (odds ratio 0.82, 95 % CI 0.70–0.97). In addition, the dose–response meta-analysis indicated that for each serving per week, or 10 g per day increment of carrot intake, the risk estimate of prostate cancer was 0.95 (0.90–0.99) or 0.96 (0.94–0.99). There was no evidence of significant publication bias based on Begg’s funnel plot (P = 1.000) or Egger’s test (P = 0.804).
Carrot intake might be inversely associated with prostate cancer risk. Because of the limited number of cohort studies and substantial heterogeneity observed between studies in this meta-analysis, further well-designed prospective studies are warranted to confirm the findings from our study.
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This study was supported by grants from the National Key Clinical Specialty Construction Project of China, key medical disciplines of Zhejiang Province, combination of traditional Chinese and Western medicine key disciplines of Zhejiang Province (2012-XK-A23), health sector scientific research special project (201002010), National Natural Science Foundation of China (Grant No. 81101717), and Zhejiang Provincial Natural Science Foundation of China (Grant No. Y2110120).
Conflict of interest
The authors declare no conflict of interest.
Xin Xu and Yunjiu Cheng are equal contributors and co-first authors to this paper.
Electronic supplementary material
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Supplementary material 1 Figure S1 Galbraith plot analysis was used to evaluate heterogeneity. It indicated that two studies were the potential source of heterogeneity. (TIFF 757 kb)
Supplementary material 2 Figure S2 Results from cumulative meta-analysis of the association between carrot intake and risk of prostate cancer. The circles and horizontal lines show the accumulation of estimates as results from each study were added, rather than the estimate for each individual study (TIFF 813 kb)
Supplementary material 3 Figure S3 Trim-and-fill analysis identified two imputed study, which is represented by two red square. (TIFF 739 kb)
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Xu, X., Cheng, Y., Li, S. et al. Dietary carrot consumption and the risk of prostate cancer. Eur J Nutr 53, 1615–1623 (2014). https://doi.org/10.1007/s00394-014-0667-2
- Prostatic neoplasms