Written by Chrystal Moulton, Staff Writer. In a review including 712,195 participants, the risk of breast cancer decreased by an average 7% for every 10 grams of fiber consumed daily.  

Breast cancer is the second leading cause of death in women diagnosed with cancer. Since its discovery to the present, a number of associations have been made between the amount of new cases or incidences of breast cancer and a variety of ethnic, socioeconomic, environmental, and genetic factors. There is no certain test that would tell an individual they will develop breast cancer. Nonetheless, the associations found to date have identified risk factors that contribute to development of the disease. This includes gender, age, presence of certain chronic diseases or cancers, food, and lifestyle factors.(1) Food, especially dietary fiber, has long been thought to prevent the development of breast cancer. Results from studies assessing breast cancer risk in relation to consumption of dietary fiber have yielded varying results, until now. Three recent studies have shown a significant decrease in breast cancer occurrence with an increase in dietary intake of fiber.(2) Researchers were still curious, nevertheless, whether studies done thus far truly agree with this relationship.

In order to confirm the relationship between fiber intake and breast cancer (2), researchers performed a literature search through Pubmed (a scientific database). They wanted to review and summarize current evidence on the association of breast cancer and dietary fiber, examine the relationship based on study design, and determine whether high or low doses of fiber affect the occurrence of breast cancer (called a dose-dependant relationship). The search identified 10 relevant studies accounting for a total of 16,848 cases and 712,195 participants.

In order to determine the relationship between fiber intake and the occurrence breast cancer, researchers calculated what is called the relative risk. When comparing groups of people, relative risk is the ratio or likelihood that an event or disease (in this case, breast cancer) might occur in one group as opposed to another. If the relative risk is greater than 1, then there is an increased risk of developing the specified disease. However, if the relative risk is less than 1 this means that the individuals have a low risk of developing the disease.(3)

In this analysis, researchers assessed studies with women aged 40-70 years old from around the world who were observed for as long as 16 years to see if breast cancer was related at all to their consumption of fiber. Within each study, the women were broken down into five groups based on their consumption of fiber. The highest level of fiber consumption was noted as quintile 5 (Q5) and the lowest quintile 1 (Q1). Researchers analyzed the data and calculated the relative risk (RR) based on the 10 relevant studies they identified. They found that the relative risk between each group was RR=0.89. Therefore, as fiber intake increased from the lowest quintile to the highest quintile, the risk of developing breast cancer was reduced by 11% at each step.. Furthermore, researchers discovered that the risk of breast cancer decreased significantly by an average 7% for every 10 grams of fiber consumed daily.(2) Thus, researchers found that increased intake of dietary fiber was significantly associated with lower rates of breast cancer in women aged 40-70 years old.

With all the commercials for “natural and tasteless” fiber products that exist, and considering the data on the benefits of fiber, we might pitch the ad agencies a new idea: Breast Cancer—the 2nd leading cause of death to women in the US.  Fiber—nature’s way of preventing it.

Source: Dong, Jia-Yi, et al. “Dietary fiber intake and risk of breast cancer: a meta-analysis of prospective cohort studies.” The American journal of clinical nutrition 94.3 (2011): 900-905.

© 2011 American Society for Nutrition

Posted August 9, 2011.

Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.

References:

    1. Breast Cancer Statistics. Susan G. Komen for the Cure®
    2. Accessed July 28, 2011.
    3. Dong JY, He K, Wang P, Qin LQ. Dietary fiber intake and risk of breast cancer: a meta-analysis of prospective cohort studies. Am J Clin Nutr. 2011 Jul 20. [Epub ahead of print]
    4. What is the Difference Between Absolute and Relative Risk? Available at: STATs website. Accessed August 2, 2011.    mk/r