Dietary Canola Oil and Reduction of Breast Cancer Risk.

Increasing evidence indicates that it is not the quantity of lipid but the type of lipid intake that influences breast cancer risk. Canola oil has received considerable attention in recent years, due to its low level of saturated fat (7%), relatively high level of monounsaturated fatty acids (62 %, particularly oleic acid), and an omega-6 to omega-3 fatty acid ratio of 2:1, which falls within the recommended range of dietary strategies in cancer prevention. The health beneficial effects of canola oil are widely accepted in humans, including cardiovascular disease; however, little or no data is available regarding the effect of canola oil on breast cancer risk. The first objective was to determine if dietary canola oil reduces susceptibility to chemically-induced mammary carcinogenesis in vivo. Female Sprague-Dawley rats were randomly assigned to corn oil or canola oil supplemented diets. Mammary tumors were chemically-induced by N-nitroso-N-methylurea. Canola oil reduced tumor volumes and showed increased survival rate compared to corn oil. The second objective was to determine if canola oil treatment affects the proliferation and apoptosis in human breast cancer cells in vitro. Estrogen receptor positive human breast cancer T47D and MCF-7 cells were cultured and treated with canola oil and chemotherapeutic drugs, tamoxifen or cerulenin. Cell proliferation as well as caspase-3 and p53 activities were measured. Canola oil significantly inhibited cancer cell growth and resulted in increased expression of caspase-3 and p53 in both T47D and MCF-7 cells. Moreover, canola oil showed growth inhibitory synergistic effects with tamoxifen and cerulenin in both T47D and MCF-7 cancer cells. The results suggest that canola oil may have inhibitory effects on breast cancer cell growth, and warrants further investigation of synergistic effects of canola oil with anti-cancer drugs.