How does fiber reduce cancer risk?

by Megan Barnett
Woman holding blue, red, green, pink, black and yellow ribbons for cancer prevention

Fiber reduces the risk of cancer, this is just a fact. But do we know how? A 2023 review looking at 11 meta-analysis (statistical analysis of multiple studies ), found that those that ate more fiber had a reduced risk of esophageal, gastric, colon, rectal, colorectal adenoma, breast, endometrial, ovarian, renal cell, prostate, and pancreatic cancers. One review showed a 14% decrease in mortality from cancer between those eating the most fiber and those eating the least!

If this isn’t blowing your mind, consider this reality - we don’t have one singular medical or pharmaceutical intervention that can reduce risk of cancer, short of taking body parts out surgically. If you can grow cancer prevention in your backyard and serve it on a plate, this tool is unmatched. But, if eating soluble fiber reduces cancer risk and drops mortality, let's dive in and find out how it works. 

Reduced risk of colon cancer

  • Soluble fiber increases stool volume and decreases stool transit time, reducing concentration of carcinogens in the colon and exposure time of intestines to carcinogens.
  • Soluble fiber binds bile acids which reduces cholesterol levels linked to colon cancer.
  • Soluble fiber boosts short-chain fatty acids (SCFA), which provide energy to healthy colon cells, but help to kill cancerous colon cell.

Reduced risk of gastric & esophageal cancer

  • Soluble fiber removes nitrate from stomach that increases stomach cancer risk.
  • Soluble fiber improves acid reflux and GERD.
  • Soluble fiber prevents absorption of carcinogens in food.

Reduced risk of breast, ovarian & endometrial cancer

  • Soluble fiber inhibits estrogen reabsorption in the colon, helping to drop circulating estrogen associated with breast cancer risk.
  • Soluble fiber reduces circulation of cholesterol (a precursor of estrogen).
  • Soluble fiber reduces blood sugar imbalances and boosts insulin sensitivity.
  • Soluble fiber lowers blood pressure levels.
  • Soluble fiber reduces the risk of diabetes.
  • Soluble fiber modifies gut microbes that are involved in hormone balance.
  • Soluble fiber reduces insulin-like growth factor (IGF), which is considered a risk factor for ovarian cancer.

Reduced risk of prostate cancer

  • Soluble fiber decreases carbohydrate absorption, improving insulin sensitivity.

The big picture

The large 2023 overview that we've referenced in this article went beyond the more accepted research around fiber and cancers of the digestive tract (colorectal, gastric, and esophageal cancers) and really put the spotlight on the preventive effects of dietary fiber for malignant female tumors such as breast, ovarian and endometrial.

Beyond that, they established the strong relationship between reduced risk of pancreatic and prostate cancer and dietary fiber. But, it’s not magic. Soluble fiber has potent mechanisms in the body to remove toxins and excess hormones, balance blood sugar, boost healthy gut microbes, maintain a strong gut barrier, drop cholesterol and even remove nitrates from the gut.

But as we know, getting enough every day can be tough.

How to get 20 grams of soluble fiber every single day (and aim for 40 grams of total fiber!)

Choose 5 of the following EVERYDAY and ensure adequate soluble fiber.

  • 1 medium size avocado
  • ½ cup black beans
  • ½ cup lima beans
  • 1 cup kidney beans
  • 1 cup Brussels sprouts
  • 1 cup mashed sweet potatoes
  • 1 ½ cup broccoli
  • 1 ½ cup turnips
  • 2 cups cooked carrots
  • 2 tbsp. flax meal
  • 1 tbsp. Florasophy

Remember, 3 teaspoons a day of Florasophy can make a world of difference in your well-being.

About Megan Barnett, MS, CNS

Megan Barnett, MS

Megan Barnett, MS, CNS is a clinical nutritionist, research writer, public speaker and educator with over ten years in the field of nutrition science and functional medicine. She co-owns BioLounge, a functional medicine clinic in Portland, Oregon, and she is the co-founder and product developer of Florasophy organic soluble fiber blends. She sits on the board of directors for the American Nutrition Association where she supports the credentialing and professional development of her colleagues while providing leadership in the treatment and prevention of disease using evidence-based nutrition science.

Back to Articles