Dietary, supplement, and adipose tissue tocopherol levels in relation to prostate cancer aggressiveness among African and European Americans: The North Carolina-Louisiana Prostate Cancer Project (PCaP)

Abstract

Background Controversies remain over the safety and efficacy of vitamin E (i.e., α–tocopherol) supplementation use for the prevention of prostate cancer (CaP); however, associations of different tocopherol forms and CaP aggressiveness have yet to be examined. Methods This study examined whether food intake of tocopherols, vitamin E supplement use, and adipose tissue biomarkers of tocopherol were associated with CaP aggressiveness among African-American (AA, n=1,023) and European-American (EA, n=1,079) men diagnosed with incident CaP. Dietary tocopherols were estimated from a food frequency questionnaire, supplement use from questionnaire/inventory, and biomarkers from abdominal adipose samples measured using high-performance liquid chromatography. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated from logistic regression comparing high aggressive CaP to low/intermediate aggressive CaP, adjusting for covariates. Results Dietary intakes of α-and δ-tocopherol were related inversely to CaP aggressiveness among EAs [OR (95% CI), highest versus lowest quartile: α-tocopherol, 0.34 (0.17–0.69), Ptrend = 0.006; δ-tocopherol, 0.45 (0.21–0.95) Ptrend = 0.007]. Inverse associations between dietary and supplemental α-tocopherol and CaP aggressiveness were observed among AAs, though these did not reach statistical significance [OR (95% CI), highest versus lowest quartile: dietary α-tocopherol, 0.58 (0.28–1.19), Ptrend = 0.20; supplemental α-tocopherol, 0.64 (0.31–1.21) Ptrend = 0.15]. No significant association was observed between adipose tocopherol levels and CaP aggressiveness [OR (95% CI), highest versus lowest quartiles of α-tocopherol for EAs 1.43 (0.66–3.11) and AAs 0.66 (0.27–1.62)]. Conclusions The inverse associations observed between dietary sources of tocopherols and CaP aggressiveness suggests a beneficial role of food sources of these tocopherols in CaP aggressiveness.

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

“…The third National Health and Nutrition Examination Survey found that serum α‐T level was inversely associated with prostate cancer risk factors: testosterone, total estradiol, and sex hormone‐binding globulin 38 . An inverse correlation between serum levels of α‐T and prostate cancer risk was found among smokers in studies by Cheng et al 39 and Weinstein et al 40 Serum levels of γ‐T (highest vs lowest quartiles) were also shown to be inversely associated with the risk of aggressive or high‐grade prostate cancer in studies by Cheng et al 39 and Bauer et al 41 In the North Carolina‐Louisiana Prostate Cancer Project, a study involving 1023 African American and 1079 European American participants, however, dietary intake of both α‐T and δ‐T were inversely correlated with prostate cancer aggressiveness, but only in European Americans 42 …”

“…38 An inverse correlation between serum levels of α-T and prostate cancer risk was found among smokers in studies by Cheng et al 39 and Weinstein et al 40 Serum levels of γ-T (highest vs lowest quartiles) were also shown to be inversely associated with the risk of aggressive or high-grade prostate cancer in studies by Cheng et al 39 and Bauer et al 41 In the North Carolina-Louisiana Prostate Cancer Project, a study involving 1023 African American and 1079 European American participants, however, dietary intake of both α-T and δ-T were inversely correlated with prostate cancer aggressiveness, but only in European Americans. 42 The importance of nutritional levels of VE in influencing prostate cancer is also supported by a nested case-control study in the US, showing that three single-nucleotide polymorphism (SNP) variations (involving BUD13, ZNF259, and APOA5), which resulted in higher circulating α-T levels, were correlated with a lowered risk of prostate cancer. 43 More recently, three additional SNP variations (involving SEC14L2, we SOD1, and TTPA) were found to be associated with a lower risk of prostate cancer in subjects receiving VE in the SELECT.…”

Dietary Supplements Commonly Used by Cancer Survivors: Are There Any Benefits?

“…In an observational trial, Antwi et al investigated whether the use of vitamin E supplements was associated with prostate cancer risk in the North Carolina–Louisiana Prostate Cancer Project 115 . Study results showed no association with reported use of vitamin E supplements in the 12 months prior to study enrollment, with varying doses consumed.…”

Tocopherols in cancer: An update

“…These findings suggest that greater intake of food containing these micronutrients might be beneficial to men with PSA‐defined recurrent prostate cancer. The North Carolina‐Louisiana Prostate Cancer Project examined whether dietary intake of tocopherols, vitamin E supplement use, and adipose tissue biomarkers of tocopherols were associated with prostate cancer aggressiveness among African‐American and European‐American men . Dietary intake of α‐T and δ‐T were inversely related to prostate cancer aggressiveness in European‐Americans .…”