Fiber and breast cancer prevention

fiber and breast cancer prevention

Research shows fiber is the most important nutrient for breast cancer prevention.

Researchers have long linked certain diets to lower rates of breast cancer, but why? For estrogen/progesterone positive breast cancers, one of the most powerful tools for prevention is diet. It's true that there are genetic and environmental factors at play, but many of those risks are out of your hands. However, a few simple modifications to your diet can go a long way in preventing hormone-related cancer risk.

What the research says

The research is steeped in conflict due to the inherently challenging nature of nutrition science, but one dietary factor shines through time and time again; FIBER.

A 2016 meta-analysis clearly states "Dose-response analysis showed that every 10g/d increment in dietary fibre intake was associated with a 4% reduction in breast cancer risk, and little evidence of publication bias was found. Thus, dietary fibre consumption is significantly associated with a reduced risk of breast cancer, particularly in postmenopausal women."

What they didn't factor in is the difference between intake of soluble vs. insoluble fiber. Our perspective at Florasophy is that both forms are important, but when it comes to binding and excreting hormones, soluble fiber reigns supreme. We recommend 20g insoluble fiber and 20g soluble fiber each and every day.

Why soluble fiber is so critical for estrogen excretion

Most women don't know that their bodies are constantly working to remove excess hormones from the body. This is how: after hormones "do their job", they are converted to a different molecule that signals the liver that the hormone needs to go. The liver does some fancy biochemical magic (which requires very specific micronutrients) and attaches the hormone waste to bile which is shuttled into the gallbladder.

From there, the bile-hormone compound is secreted into the small intestine where bile has two potential routes:

  1. Bile will help you emulsify and absorb dietary fat, in which case the toxic hormone that your liver was trying to get rid of is reabsorbed into your bloodstream where it increases your hormone levels and increases risk of hormone imbalance.
  2. or
  3. The bile/hormone molecule is trapped by soluble fiber in your diet, preventing reabsorption and the new bile-hormone-fiber compound is shuttled into the colon and into your toilet as waste.

If route # 2 happens consistently, the risk of hormone imbalance and excess circulating estrogen is significantly reduced. It is this process that helps to prevent breast cancer.

How to boost soluble and insoluble fiber

Most plants contain a combination, but as a rule increasing vegetable and fruit intake will largely boost insoluble fiber, while consuming plenty of beans, lentils, oat bran, avocado, chia, and flax is an effective way to increase soluble fiber. (Learn more here about how to eat more soluble fiber).

Many people find it hard to reach the target of 20g soluble fiber with diet alone, and that is why Florasophy is such a valuable addition to your fiber routine. Every tablespoon of Florasophy contains 4g soluble fiber, so you can match your dose to your fiber needs.


About Megan Barnett, MS, CNS

Megan Barnett, MSMegan Barnett is a functional medicine practitioner in Portland, Oregon. In her clinical practice, she helps patients identify the root cause of their health problems, then designs individualized and evidence-based approaches to alleviate symptoms and help their bodies heal. She has a Bachelor of Science in Dietetics from Kansas State University and a Master of Science in Nutrition and Functional Medicine from University of Western States.