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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    • "As expected, serum vitamin A (5.6%, 0.03 mg/L) and vitamin E (8.2%, 0.88 mg/L) levels also were significantly increased after nutrition intervention. Higher dietary intakes and blood concentrations of carotenoids (precursor of vitamin A), including β-carotene, have been shown to reduce breast cancer risk although not entirely consistent [29,30]. According to results by performing a meta-analysis of 11 studies, intake of 7,000 µg per day or more of β-carotene was associated with 18% reduction of breast cancer risk compared with intake of 1,000 µg per day or less [31]. "
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    01/2014; 3(1):39-47. DOI:10.7762/cnr.2014.3.1.39
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    • "Individual constituents in whole foods may be factors that contribute to a reduction in cancer risk (1–3). While the experimental data supporting the role of individual phytochemicals in cancer prevention are convincing (4–6), epidemiological studies that have attempted to identify the association between dietary ingredients and cancer have yielded less convincing results (7–10). "
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    • "Lycopene (LYP) has been shown to be one of the most efficient singlet oxygen quencher and peroxyl radical scavengers among all the carotenoids and is more effective than 毩 -tocopherol [6] . A number of studies have shown that LYP can protect native low density lipoprotein from oxidation and can suppress cholesterol synthesis. "
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