Abstract
Objectives
Diet is a source of exposure to pesticides. Organic food consumption may lower cancer risk, possibly due to decreased exposure to pesticides. Few studies have investigated the association between organic food consumption and cancer risk and evidence on the risk of breast cancer is limited.
Methods
We used data from 39,563 Sister Study participants aged 35 to 74 years who enrolled in 2003–2009 and had information available on frequency of organic food consumption. Participants reported their consumption of organic produce, meat, and dairy during the past 12 months as never, less than half the time, about half the time, and more than half the time. An organic diet score was calculated by assigning scores of 0, 1, 2 and 3 for increasing consumption proportions and summing across foods (maximum score 9). We used Cox proportional hazards models to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for breast cancer associated with ever consuming organic foods and organic diet scores, adjusting for potential confounders, including known risk factors for breast cancer.
Results
At baseline, 61.8% of women reported ever eating organic produce, meat, or dairy. We identified 2336 incident breast cancers diagnosed at least 1 year after enrollment (mean follow-up 9.0 years). Any organic food consumption was inversely associated with breast cancer (HR: 0.87 [95% CI, 0.80–0.95]), especially estrogen receptor negative cancer (HR: 0.77 [95% CI, 0.61–0.98]). There was no trend with increasing organic diet score based on all organic food types. Consumption of organic produce half or more than half the time was associated with reduced risk of breast cancer compared to no organic produce consumption (HR: 0.87 [95% CI, 0.77–0.99]). There was no trend for organic dairy or meat consumption. In stratified analyses, associations did not differ by demographics, obesity, menopausal status, lifestyle characteristics, cancer screening, or degree of family history.
Conclusions
Although unmeasured factors associated with consuming organic foods may explain these results, organic produce consumption was associated with reduced breast cancer risk.
Funding Sources
National Institute of Environmental Health Sciences.
Association of Frequency of Organic Food Consumption With Cancer Risk
