Effect of vitamin E supplementation on uterine cervical neoplasm: A meta-analysis of case-control studies

Abstract

Several epidemiological studies have suggested that vitamin E could reduce the risk of uterine cervical neoplasm. However, controversial data were presented by different reports. Hence, we conducted a meta-analysis to assess the relationship between vitamin E and the risk of cervical neoplasia. We performed a comprehensive search of the PubMed, Embase and Cochrane databases through December 31, 2016. Based on a fixed-effects or random-effects model, the odds ratio (OR) and 95% confidence intervals (CIs) were calculated to assess the combined risk. Subgroup analyses and meta-regression were done to assess the source of heterogeneity. Subgroup analyses were performed according to survey ways, types of cervical neoplasia, study populations. A protocol was registered with PROSPERO (No. CRD42016036672). In total, 15 case-control studies were included, involving 3741 cases and 6328 controls. Our study suggested that higher category of vitamin E could reduce the cervical neoplasia risk (OR = 0.58, 95% CIs = 0.47–0.72, I2 = 83%). In subgroup-analysis, both vitamin E intake and blood levels of vitamin E had a significant inverse association with the risk of cervical neoplasm. Additionally, we found the same relationship between vitamin E and cervical neoplasia among different populations and types of cervical neoplasia. Meta-regression showed that none of the including covariates were significantly related to the outcomes. No evidence of publication bias was observed. In conclusion, vitamin E intake and blood vitamin E levels were inversely associated with the risk of cervical neoplasia.

Vitamin E and cancer prevention: Studies with different forms of tocopherols and tocotrienols

“…Higher VE intake was found to be associated with a lower risk of invasive cervical cancer in a case‐control study in China 59 . This finding was corroborated in a meta‐analysis that involved 15 case‐control studies and found an inverse relationship between VE intake and cervical cancer 79 . Also, in meta‐analyses, inverse associations were observed between serum levels of α‐T and breast cancer risk by Hu et al 80 as well as renal cancer by Shang et al 81 and Shen et al 82 In the combined Shanghai Women's and Men's Health Studies, dietary VE intake (including supplements) was inversely associated with liver cancer risk 60 .…”

“…In a meta‐analysis of 69 prospective studies by Aune et al, 84 even though there was no relevant link between dietary VE intake and cancer incidence or total mortality, an increase of 5 µg/mL in serum α‐T level was linked to a 9% or 6% decrease in total cancer rate or total mortality rate, respectively. Meta‐analysis that focused on serum VE levels were more likely to find an inverse association 75,76,79,80 . Genetic SNP's that resulted in an increase of serum α‐T levels were shown to be associated with a decrease in cancer risk 43,44 .…”

“…59 This finding was corroborated in a meta-analysis that involved 15 case-control studies and found an inverse relationship between VE intake and cervical cancer. 79 Also, in meta-analyses, inverse associations were observed between serum levels of α-T and breast cancer risk by…”

“…Meta-analysis that focused on serum VE levels were more likely to find an inverse association. 75,76,79,80 Genetic SNP's that resulted in an increase of serum α-T levels were shown to be associated with a decrease in cancer risk. 43,44 All these results support the concept that insufficiency in VE nutrition increases cancer risk.…”

The Relationship between the Serum Level of Selenium and Cervical Intraepithelial Neoplasia: A Comparative Study in a Population of Nigerian Women

“…Ehiozogie Obhielo 1 , Michael Ezeanochie 2 *, Oghenefegor Olokor O 2 , Anthony Okonkwo 2 , Etedafe Gharoro 2 component of the intracellular antioxidant glutathione peroxidise enzyme has been shown from several lines of evidence to have a protective effect against cancer development (Cunzhi et al, 2003;Kim et al, 2003). Recent studies suggest that risk of premalignant disease of the cervix increases with decreasing serum antioxidant system activity and reduced serum levels of micronutrients such as selenium and Vitamin E (Kim et al, 2003;Hu et al, 2017).…”