This post is from the Top 10 list printed in the spring 2016 issue of Beyond Blue. Read below to get 3 bonus tips & references to the studies behind the information! To read Beyond Blue, go here.

Written by Sharyn Worrall with medical review by Tim Byers, M.D., MPH, University of Colorado

The news often reports on vitamins or specific foods as they relate to cancer, and studies are conducted yearly in an honest effort to understand the role nutrients play in cancer prevention, treatment and survivorship.

However, studies generally have inconsistent results, suggesting that adding or removing one single item to the diet has little effect on health.

What is recommended for cancer prevention and recurrence, based on consistent reliable research, is maintaining a healthy weight, exercising and eating a balanced diet.

Foods and supplements will continue to make headlines as “cure-alls” in the colorectal cancer community, but it’s important to take the news with a grain of salt.

Take a look at the list below to learn about some items that caused a stir over the past few years.


There may be a lower risk of CRC recurrence for stage III patients who drink 4+ cups of coffee per day compared to non-coffee drinkers. Limited studies and small samples suggest more research is needed to understand this relationship.

  • Tip:  If you’re not already a coffee drinker, best to not start guzzling espresso.

2.Red meat

bacon-colon-cancer-riskA 2015 meta-analysis reported a 17% increased risk for people eating 100g/day of red meat (about ¼ lb. burger), and an 18% increase for people eating 50g/day of processed meat (about 1 hot dog).

This increase seems alarming, however, the average lifetime risk of CRC only increases from 5% to 6%.

  • Tip: Eating meat on occasion is okay, but consider incorporating plenty of meat-free meals as well.


This root is filled with curcumin, an antioxidant known to reduce inflammation. Studies on curcumin indicate cancer prevention benefits, however, studies on curcumin and CRC treatment have mixed results. Some studies suggest curcumin negatively interferes with chemo and radiation therapies, whereas others have suggested more research on the combination of curcumin and 5-FU (Bhaumik, 2008).

4.Vitamin D

High levels of Vitamin D are associated with longer CRC survivorship, yet, results of CRC risk reduction as a result of Vitamin D are unclear. Large observational studies point to reduced risk of CRC in people with high levels of serum Vitamin D (Jenab M, et al, 2010).

  • Tip: If possible, get Vitamin D from natural food sources like wild salmon or egg yolks, or by spending a bit more time in the sun.


There’s little controversy around fiber and its benefits. Insoluble fiber is most commonly linked with cancer protection, while soluble fiber has a host of other health benefits. Ten grams of dietary fiber per day reduces CRC risk by 10%.

  • Tip: Get more fiber by eating whole foods like cooked oatmeal, broccoli, apples and kidney beans.
  • Tip: If you’re on a low-residue diet, best to avoid fiber.

VitaminC-colon-cancer6.Vitamin C

Most experts recommend getting this vitamin from whole fruits and vegetables rather than supplements or store bought juices (usually filled with added sugar). Intravenous vitamin C has been associated with improved quality of life. Vitamin C has shown some benefits in lab mice, it has not shown any reliability in affecting CRC in humans.


Many population-based studies have shown that people who eat more garlic have lower risk of CRC. Although the NCI recognizes garlic’s anti-cancer benefits, it doesn’t recommend the use of garlic for cancer prevention due to research method variation.

  • Tip: The World Health Organization suggests 1 clove/day for good health.


There are many types of antioxidants (commonly called free radical fighters!), and most have unclear evidence related to CRC prevention and survivorship. What researchers do know for certain is that fruits and vegetables have high levels of antioxidants, and fruits and vegetables are linked with good health, cancer prevention and recurrence.

  • Tip: Get your antioxidants from whole foods versus supplements.

9.Omega 3 Fatty Acids

Some studies have shown that Omega-3 Fatty Acids increase risk of CRC, while others have shown it to decrease risk (MacLean et al, 2006). Omegas are great for heart health, to treat colitis and to reduce inflammation, but it’s effects on CRC are mixed and unreliable.

10.Green Tea

This drink is filled with polyphenols – antioxidants that give green tea its healthful benefits. Three cups of green tea per day has been shown to lower cancer risk, and a few small studies suggest that green tea paired with chemo may improve patient outcomes (Yang, 2011; Toden, 2016). More randomized control trials are needed to understand these links before green tea can be recommended as an adjunct to treatment.

  • Tip:  Drinking green tea could be a great addition to overall wellness regimens, but avoid getting it from pills or extracts as these are linked to liver toxicity (Mazzanti, 2015).

11.Beer and Wine

There’s an association between heavy beer-drinking (> 2 beers per day) and CRC (Zhang, 2015). Red wine on the other hand, is seen to have some anticancer properties in human cells and lab animals due to the antioxidant, resveratrol found in the skin of grapes. No human clinical trials clearly support this link (Athar, 2007), so for now drink responsibly.

spinach-colon-cancer-risk12.Folic Acid and Folate

There’s good evidence that folate prevents colorectal cancer. Foods that include folate are dark green, leafy vegetables, citrus fruits and lentils. Interestingly enough, however, there’s strong evidence that folic acid, the synthetic form of folate, increases the risk of cancer (Fife et al 2011). If possible, get your folate from food, not supplements.


Sadly, the link between colorectal cancer and chocolate is not as simple as we hoped. Studies that have shown benefits were done on rats, who, for 8 weeks, consumed 12% of their diet in the form of cocoa, not Hershey’s. Over the 8-week period, the rats had a reduced risk of developing polyps and potentially CRC – however, this was at a very early stage, and the study concluded at that time.

No Single Food

Research has shown us that no supplement or single food item has the power to prevent, reverse or cause cancer, but that doesn’t mean eating a healthy diet shouldn’t be a top priority alongside physical activity since obesity is very clearly a CRC risk factor.

Eating a variety of fruits, vegetables and whole grains to to ensure proper vitamin and nutrient intake is needed for good health and wellness management.

Always talk to your medical team before adding any dietary supplements or making drastic changes to your diet.

More Information About Nutrition

Pearl Point

American Cancer Society

National Cancer Institute


Athar, Back, Tang, et al. Resveratrol: a review of preclinical studies for human cancer prevention. Toxicology and Applied Pharmacology 2007; 224(3):274-283.

Bhaumik, et al. Curcumin enhances the effects of 5-fluorouracil and oxaliplatin in mediating growth inhibition of colon cancer cells by modulating EGFR and IGF-1R. Internation Journal of Cancer. Jan 2008. Vol 122, Issue 2, p 267-273.

Fedirko V et al. Prediagnostic 25-hydroxyvitamin D, VDR and CASR polymorphisms, and survival in patients with colorectal cancer in western European populations. Cancer Epidemiol Biomarkers Prev. 2012 Apr;21(4):582-93. PMID: 22278364

Fife, Raniga, Hider, Frizella. Folic acid supplementation and colorectal cancer risk: a meta-analysis. Colorectal Disease. 2011; 13(2):132-7.

Fleischauer AT, Arab L. Garlic and Cancer: A critical review of the epidemiologic literature. Journal of Nutrition, 2001. 131(3s):1032S-1040S.

Fujiki, Imai, Nakachi, Shimizu, Moriwaki, Suganuma. Challenging the effectiveness of green tea in primary and tertiary cancer prevention. Journal of Cancer Research and Clinical Oncology. 2012. 138(8): 1259-70.

Gorham, Edward, et al. Optimal vitamin D status for colorectal cancer prevention: a quantitative meta analysis. American Journal of Preventive Medicine, 2007. 32(3) 210-216.

Guercio BJ et al. Coffee intake, recurrence, and mortality in stage III colon cancer: results from CALGB 89803 (alliance). Journal of Clinical Oncology, 2015; 33(31):3598-607.

Grant, William. A critical review of Vitamin D and Cancer. Dermatoendocrinol. 2009. Jan-Feb; 1(1):25-33.

International Agency for Research on Cancer (IARC). Carcinogenicity of consumption of red and processed meat. Lancet Oncology, 2015.

Jenab M et al. Association between pre-diagnostic circulating vitamin D concentration and risk of colorectal cancer in European populations: a nested case-control study. BMJ. 2010 Jan 21;340:b5500. PMID: 20093284

Mazzanti, DiSotto, Vitalone. Hepatotoxicity of green tea: an update. Arch Toxicology. 2015. Aug 89(8):1175-91.

MacLean, et al. Effects of omega-3 fatty acids on cancer risk: a systematic review. The Journal of the American Medical Association. 2006. 295(4)403-15.

Memorial Sloan Kettering Cancer Center (MSKCC). Turmeric, 2016.

Mingyang, et al. Plasma 25-hydroxyvitamin D and colorectal cancer risk according to tumor immunity status. Gut. 2015

National Cancer Institute. High-dose vitamin C-patient version (PDQ).

National Cancer Institute. Garlic and cancer prevention.

Toden, Tran, Tovar-Camargo, Okugawa, Goel. Epigallocatechin-3gallate targets cancer stem-like cells and enhances 5-fluorouracil chemosensitivity in colorectal cancer. Oncootarget, 2016.

Y-I Kim. Folate: a magic bullet or double edged sword for colorectal cancer prevention.

Yang, zheng, Xiang, Gao, Li, Zhang, Gao, Shu. Green tea consumption and colorectal cancer risk: a report from the Shanghai Men’s Health Study. Carcinogenesis. 2011. 32(11):1684-8.

Yun et al. Vitamin C selectively kills KRAS and BRAF mutant colorectal cancer cells by targeting GAPDH. Science 2015. 11;350(6266): 1391-16

Zhang and Zhong. Consumption of beer and colorectal cancer incidence: a meta-analysis of observational studies. Cancer Causes Control. 2015. 26(4):549-60.

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