Vitamin A intake and risk of melanoma: a meta-analysis

Abstract

Background: Mounting evidence from experimental and animal studies suggests that vitamin A may have a protective effect on melanoma, but the findings on the association of vitamin A intake with risk of melanoma have been inconsistently reported in epidemiologic studies. We attempted to elucidate the association by performing a meta-analysis.

Methods: Eligible studies were identified by searching PubMed and EMBASE databases, as well as by reviewing the references of retrieved publications. Summary odds ratios (OR) with corresponding 95% confidence interval (CI) were computed with a random-effects model. Study-specific ORs and 95% CIs for the highest vs. lowest categories of vitamin A intake were pooled.

Results: A total of 8 case-control studies and 2 prospective studies comprising 3,328 melanoma cases and 233,295 non-case subjects were included. The summary OR for the highest compared with the lowest intake of total vitamin A, retinol and beta-carotene was 0.86 (95% CI = 0.59-1.25), 0.80 (95% CI = 0.69-0.92) and 0.87 (95%CI = 0.62-1.20), respectively. Significant heterogeneity was observed among studies on vitamin A and beta-carotene intake, but not among studies on retinol intake. Subgroup and sensitivity analyses confirmed these findings. There was no indication of publication bias.

Conclusion: Findings from this meta-analysis suggest that intake of retinol, rather than of total vitamin A or beta-carotene, is significantly associated with reduced risk of melanoma.

Figure 1. Flow diagram of systematic literature search.

Figure 2. Odds ratios and 95% confidence interval of melanoma for the highest vs. lowest intake of vitamin A for individual studies and all studies combined.

Figure 3. Odds ratios and 95% confidence interval of melanoma for the highest vs. lowest intake of retinol for individual studies and all studies combined.

Figure 4. Odds ratios and 95% confidence interval of melanoma for the highest vs. lowest intake of beta-carotene for individual studies and all studies combined.