Updated: May 30
Breast cancer is one of the most common cancers among American women. It is estimated by the American Cancer Society that in 2021 alone, around 281,550 new cases of breast cancer will be diagnosed and around 43,600 women will die from breast cancer. That's 43,600 too many. These numbers are profound and illustrate the importance, as a woman, to do everything in your power to mitigate your risks. In addition to getting annual mammograms and doing regular self breast exams, research studies provide convincing evidence that lifestyle factors, such as diet and exercise, can influence breast cancer risk. The American Cancer Society offers dietary guidelines that emphasize the importance of consuming fruits, vegetables, beans, and whole grains to prevent breast cancer. These foods have something in common — fiber.
It may be the fiber in these plants or it may be the more than 25,000 phytonutrients (plant nutrients) that accompany eating whole plant-based foods. There are many proposed mechanisms in which plant-based or plant-centric diets can help to reduce the risk of breast cancer. For today, we'll focus on four proposed mechanisms of how dietary fiber may help to reduce the risk of breast cancer. And, stay tuned as we have two upcoming articles in queue: soy's role in breast cancer prevention and phytonutrients' role in breast cancer prevention.
How does fiber reduce the risk of breast cancer?
Improves insulin sensitivity
One proposed mechanism that’s been studied is fiber’s role in improving insulin sensitivity. Insulin sensitivity refers to how sensitive the body's cells are in response to insulin. High insulin sensitivity means that the cells of the body use blood glucose more effectively, reducing blood sugar. Some lifestyle and dietary changes may help improve insulin sensitivity like getting adequate sleep, exercising regularly, and eating a diet high in fiber. Evidence shows that high levels of insulin and insulin-like growth factor 1 (another hormone similar to insulin) play roles as independent breast cancer risk factors. More fiber in the diet equates to increased insulin sensitivity and decreased levels of insulin and insulin-like growth factor, therefore reducing the risk of breast cancer.
Mitigates estrogen dominance
Another mechanism that has been studied is dietary fiber’s role in decreasing the amount of estrogen in blood circulation. Dietary fiber can help to manage excess estrogen by excreting it through digestion, which decreases the plasma concentration of estrogen. Decreased plasma concentration of estrogen has been shown to reduce breast cancer risk. Wondering about where excess estrogen comes from? Diet may play a role. A diet high in saturated fats and processed food, much like the standard American diet, may lead to estrogen dominance. Whole plant-based foods not only have plenty of fiber, but they also have healthier fats that may help to mitigate estrogen dominance.