Chemopreventive Activity of Vitamin E in Breast Cancer: A Focus on γ- and δ-Tocopherol

Abstract

Vitamin E consists of eight different variants: α-, β-, γ-, and δ-tocopherols (saturated phytyl tail) and α-, β-, γ-, and δ-tocotrienols (unsaturated phytyl tail). Cancer prevention studies with vitamin E have primarily utilized the variant α-tocopherol. To no avail, a majority of these studies focused on variant α-tocopherol with inconsistent results. However, γ-tocopherol, and more recently δ-tocopherol, have shown greater ability to reduce inflammation, cell proliferation, and tumor burden. Recent results have shown that γ-enriched mixed tocopherols inhibit the development of mammary hyperplasia and tumorigenesis in animal models. In this review, we discuss the possible differences between the variant forms, molecular targets, and cancer-preventive effects of tocopherols. We recommend that a γ-enriched mixture, γ- and δ-tocopherol, but not α-tocopherol, are promising agents for breast cancer prevention and warrant further investigation.

Alpha-tocopherol and gamma-tocopherol concentration in vegetable oils

“…This information regarding the sunflower oil is in accordance with the statement that this compound is found in higher concentrations in wheat germ oils, olive oil and sunflower oil (Traber, 2006;Gliszczyńska-Świgło et al, 2007;Smolarek & Suh, 2011;Velasco et al, 2010).…”

Specific siRNA Targeting Receptor for Advanced Glycation End Products (RAGE) Decreases Proliferation in Human Breast Cancer Cell Lines

“…Breast cancer is the most common malignancy and the second leading cause of death in women [1,2]. The causes and pathogenesis of breast cancer are poorly understood [2].…”

Role of dietary bioactive natural products in estrogen receptor-positive breast cancer

“…Vitamin E consists of eight different forms which include four tocopherols (α-, β-, γ-, and δ-forms) and four tocotrienols (α-, β-, γ-, and δ-forms) [297]. The major dietary sources of tocopherols are vegetable oils, such as corn, soybean, sesame and canola oils [297].…”

“…The major dietary sources of tocopherols are vegetable oils, such as corn, soybean, sesame and canola oils [297]. α-Tocopherol has a higher bioavailability than other forms of vitamin E. Because the acetate form is less susceptible to oxidative destruction, α-tocopherol acetate is widely used as source of vitamin E [298].…”