Antioxidants and breast cancer risk- a population-based case-control study in Canada

Centre for Chronic Disease Prevention and Control, Public Health Agency of Canada, Ottawa, Ontario, Canada.
BMC Cancer (Impact Factor: 3.36). 08/2011; 11(1):372. DOI: 10.1186/1471-2407-11-372
Source: PubMed


The effect of antioxidants on breast cancer is still controversial. Our objective was to assess the association between antioxidants and breast cancer risk in a large population-based case-control study.
The study population included 2,362 cases with pathologically confirmed incident breast cancer (866 premenopausal and 1,496 postmenopausal) and 2,462 controls in Canada. Intakes of antioxidants from diet and from supplementation as well as other potential risk factors for breast cancer were collected by a self-reported questionnaire.
Compared with subjects with no supplementation, 10 years or longer supplementation of zinc had multivariable-adjusted odds ratios (OR) and 95% confidence intervals (CI) of 0.46 (0.25-0.85) for premenopausal women, while supplementation of 10 years or longer of multiple vitamin, beta-carotene, vitamin C, vitamin E and zinc had multivariable-adjusted ORs (95% CIs) of 0.74 (0.59, 0.92), 0.58 (0.36, 0.95), 0.79 (0.63-0.99), 0.75 (0.58, 0.97), and 0.47 (0.28-0.78), respectively, for postmenopausal women. No significant effect of antioxidants from dietary sources (including beta-carotene, alpha-carotene, lycopene, lutein and zeaxanthin, vitamin C, vitamin E, selenium and zinc) or from supplementation less than 10 years was observed.
This study suggests that supplementation of zinc in premenopausal women, and supplementation of multiple vitamin, beta-carotene, vitamin C, vitamin E and zinc in postmenopausal women for 10 or more years may protect women from developing breast cancer. However, we were unable to determine the overall effect of total dose or intake from both diet and supplement.

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    • "It should be given in the esterified formulation as zinc picolinate that is best taken up by the intestinal tract (Barrie et al., 1987). In association with multivitamins, long-term supplementation with zinc was found also to protect from developing certain cancers (Pan et al., 2011). When given together with vitamin B6 (Cunnane et al., 1984; Bordoni et al., 1998), zinc promotes the conversion of short-chain omega-3 poly-unsaturated fatty acids (such as alpha linolenic acid: 18 : 3 x3) into their long-chain derivatives by acting as co-factors of the elongase and desaturase enzymes (Ayala & Brenner, 1987). "
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