Prevent Colorectal Cancer


How can you reduce the risk of colorectal cancer?

The word cancer frightens many of us, and colorectal cancer has the double-whammy of being both common and deadly. It’s the fourth most common cancer and the second leading cause of death from cancer, according to the National Cancer Institute.

Approximately 4.5 percent of the population will be diagnosed with colorectal cancer, with a five-year survival rate of 65 percent. Genetics only account for 5 to 10 percent of colorectal cases (and family history up to 25 percent), which means you can tremendously reduce your risk through diet and lifestyle as well as herbs and supplements. There are two primary themes to remember when it comes to reducing colorectal cancer risk: reducing inflammation and oxidative stress and encouraging healthy gut function, including microbiota.

  1. Healthy Lifestyle & Regular Screening

    One of the best ways to reduce your risk of colon cancer is to exercise regularly, at least 30 minutes on most days. For optimal protection, researchers suggest 3.5 to 4 hours per week of vigorous activity.

    Inactivity has a greater impact on colorectal cancer risk than genetics. While it may not seem connected, exercise improves gut motility, enhances the immune system, decreases inflammatory insulin and insulin-like growth factors, decreases obesity, and improves antioxidant status.

    It’s also crucial to be screened and to remove polyps larger than the size of a pea, which are more likely to turn into cancer. Fortunately, they grow slowly over 10 to 20 years. Other healthy lifestyle changes include not smoking, avoiding obesity, controlling blood sugar, and keeping alcohol intake below three glasses daily.

  2. Colon-Friendly Diet

    One of the primary reasons colorectal cancer is so common in the United States is the standard American diet. Studies link colorectal cancer risk to excessive red meat, fat, protein, and calories. A whole-foods diet emphasizing vegetables, fiber, fatty fish like salmon and halibut, plant protein, and good hydration significantly protects you because it feeds healthy gut flora (also called microbiota or microbiome), encourages healthy elimination, decreases inflammation and oxidation, balances blood sugar, and nourishes the body.

    Quick Tip: Embrace Fiber

    One meta-analysis found that people who consumed more than 27 grams of fiber daily had 50 percent less chance of developing colorectal cancer compared to people who consumed less than 11 grams of fiber daily.

  3. Herbs & Supplements

    You may also boost your resistance to colorectal cancer—and cancer in general—with the following supplements.

    The most human studies have been performed on turkey tail mushrooms, usually as an adjunct in cancer treatment to improve outcome and remission rates. In these studies, turkey tail extract kept colorectal cancer progression in check, decreased the voracity of cancer’s progression (how deep it went, how far it spread), and increased survival rate in colorectal cancer patients also receiving conventional care. A handful of studies also show that reishi, shiitake, and chaga extracts also inhibit colorectal cancer.

    • Calcium and Vitamin D

      In population studies, the better the intake of these nutrients, the lower the risk. Although not all studies agree, some note a reduced risk on par with exercise: 10 to 15 percent. In a four-year, well-designed study, the combination of 1,400-1,500 milligrams (mg) calcium citrate or carbonate and 1,000 IU vitamin D3 together reduced cancer risk for healthy postmenopausal women. Other studies have found that vitamin D supplementation reduces risk by 50 percent.

    • Probiotics & Prebiotics

      Gut flora have a tremendous impact on colorectal health and cancer risk. Preliminary studies suggest that probiotics (healthy bacterial flora including Lactobacillus acidophilus and Bifidobacterium from supplements and lactic acid-forming fermented foods) and prebiotics (food for the good bacteria including fiber, mucilage, FOS, and inulin) improve gut health and motility, make the colon less hospitable to cancer cells, fight and prevent cancer cells and tumor formation, and reduce the damage from carcinogenic foods like grilled red meat, cured meat, and bacon.

    • Medicinal Mushrooms

      Mushrooms have long been used in Asia for cancer treatment and prevention. They contain complex polysaccharide starches called glucans as well as other beneficial compounds that improve immune system health to better fight and prevent cancer.

    • Omega-3 Fatty Acids

      People who consume more omega-3 fatty acids from wild, coldwater fatty fish have a reduced risk of colon, breast, and prostate cancers. Taking 2.5 grams of fish oil daily reduces cancer’s growth rate. Higher doses of fish oil (4.1 grams EPA, 3.6 grams DHA daily) for 12 weeks rapidly reduced cancer markers in colon polyps in a small group of high-risk cancer patients.

    • Turmeric

      This potent anti-inflammatory spice and its constituents slow the promotion and progression of colon cancer and encourage cancer cell cycle arrest. Cancer patients who consumed turmeric powder (as well as garlic, onion, tomato, shiitake, rice bran, kale, blueberry, and pineapple) in addition to their regular diet improved antioxidant status and other clinical measures of improved treatment outcomes versus those who did not. One study suggested a dose of 3.6 grams of curcumin for colon care.

    • Green Tea

      Five or more cups of green tea daily or 250 to 500 mg of the standardized extract daily provides antioxidants and can improve the immune system’s response to cancer, particularly in nonsmokers. In colorectal cancer, EGCG in green tea inhibits cancer growth, induces cancer cell death, and inhibits the inflammation that fuels cancer. In one study, green tea supplementation reduced colorectal tumor incidence in post-surgery cancer patients by 50 percent.


Anticancer: A New Way of Life by David Servan-Schreiber ($18, Penguin Books, 2017) 

“Antioxidant and Anticoagulant Status Were Improved by Personalized Dietary Intervention ... in Cancer Patients” by G.Y. Lee et al., Nutr Cancer, 9/2/15

“Antitumor Activity of Water Extract of a Mushroom, Inonotus obliquus, Against HT-29 Human Colon Cancer Cells” by S.H. Lee et al., Phytotherapy Research, 4/15/09 

The Cancer-Fighting Kitchen by Rebecca Katz ($32.50, Ten Speed Press, 2017) 

“Colorectal Cancer,” National Cancer Institute, 

“Curcumol Induces Cell Cycle Arrest in Colon Cancer Cells ...” by J. Wang et al., J Ethnopharmacol, 1/10/18 

“Green Tea Catechin, Epigallocatechin-3-Gallate (EGCG) ...” by B.N. Singh et al., Biochem Pharmacol, 12/15/11 

“Green Tea Selectively Targets Initial Stage of Intestinal Carcinogenesis ...” by A.Y. Issa et al., Carcinogenesis, 9/1/07 

“Inherited Risk for Colorectal Cancer,” Memorial Sloan Kettering Cancer Center, 

“Inhibitory Effects of Culinary Herbs and Spices on the Growth of HCA-7 Colorectal Cancer Cells ...” by A. Jaksevicius et al., Nutrients, 9/21/17 

“The Intestinal Microbiota, Gastrointestinal Environment and Colorectal Cancer: A Putative Role for Probiotics in Prevention of Colorectal Cancer?” by M.A. Azcarate-Peril et al., Am J Physiol Gastrointest Liver Physiol, 6/23/11


Maria Noël Groves, RH (AHG)

Maria Noël Groves, RH (AHG), is a registered clinical herbalist and freelance health journalist nestled in the pine forests of New Hampshire. Her herb book, Body into Balance, hits bookstores in March. Learn about herbs, distance health consults, online classes, and more at