Written by Jessica Patella, ND. In a study including 438 women with breast cancer, there was a 64% risk reduction with vegetable fiber, 51% reduction with fruit fiber, but no benefit from soy or cereal fiber.
Breast cancer is the second most common form of cancer in women (1). Although death rates from breast cancer have been declining since 1990, there is still a 1 in 35 (3%) chance a woman will die from breast cancer (1). For this reason, many women are becoming more aware of preventative options. Recent research has shown diets high in fiber are protective against breast cancer (2).
A hospital-based study was conduced comparing 438 women with breast cancer to 438 control participants (women without any history of cancer, matched by age and residence – rural/urban) (2). Infiltrating duct carcinoma was the most common type of breast cancer (388 subjects, 88.6%), followed by ductal carcinoma in situ (27 subjects, 6.2%), mucoid carcinoma (8 subjects, 1.8%), lobular carcinoma (5 subjects, 1.1%), neuroendocrine carcinoma (4 subjects, 0.9%), medullary carcinoma of the breast (3 subjects, 0.7%), tubular carcinoma (2 subjects, 0.5%) and micropapillary carcinoma (1 subject, 0.2%) (2).
Fiber intake was determined from an 81-item questionnaire and broken into cereal, soy, vegetable and fruit fiber. Compared with the control participants’ fiber intake (10.6 g per day), consumption of total dietary fiber, soy fiber, vegetable fiber and fruit fiber was significantly lower in the participants with breast cancer (total fiber less than 5.57 g per day) (2). No significant difference was observed between the two groups with cereal fiber intake (2).
After the statistical analysis of the highest versus the lowest intake, a decreased risk of breast cancer was found only with higher intakes of vegetable fiber (Odds ratio= 0.36; 95% CI =0.24-0.56; p= 0.013) and fruit fiber (Odds ratio= 0.49; 95% CI =0.32-0.74; p= 0.001). Higher intakes of soy and cereal fiber were not found to reduce the risk of breast cancer (2). Since fruits and vegetables have many other substances that may be beneficial; for example, antioxidants, vitamins and minerals, it is possible it is not simply the fiber that makes them more protective. Refined grains contain very little fiber, which might explain why cereal fiber was not protective against breast cancer (2).
In conclusion, consumption of fiber and other components from fruits and vegetables was shown to reduce the risk of breast cancer (2). Consumption of fiber was determined by a food-recall questionnaire and recall bias could be an issue. Future research where participants record their foods daily would give a more accurate assessment of total fiber intake and posssible effect of antioxidants and other components.
Source: Zhang, C. X., et al. “Effect of dietary fiber intake on breast cancer risk according to estrogen and progesterone receptor status.” European journal of clinical nutrition 65.8 (2011): 929-936.
© 2011 Macmillan Publishers Limited,
Posted May 31, 2011.
References:
- Breast Cancer. American Cancer Society.
- Zhang CX, et al. Effect of dietary fiber intake on breast cancer risk according to estrogen and progesterone receptor status. 2011. Euro J of Clin Nutr doi:10.1038/ejcn.2011.57.
