Eat to Beat Cancer
Diet may help prevent colorectal cancer
March 2007 | by Elisabeth Hsu-Leblanc
Reprinted with permission from Taste For Life

The second leading cause of cancer mortality in the United States, colorectal cancer may be one form of this disease that’s closely related to diet. While it does not cancel out family history or environmental and lifestyle factors, a plant-based diet can help protect us, especially with regular cancer screenings.

anti-cancer diet
The Western diet (high in white and refined foods like cakes, pies, and other sweets, cheese, potatoes, pizzas, and sandwiches) appears to increase the risk for colorectal cancer. Limiting the intake of red and proc-essed meat is high on the American Cancer Society’s list of nutritional advice for fighting this cancer, along with moderating alcohol use: no more than one drink a day for women; two for men.

Research links lower colorectal cancer risk with diets high in fruits and vegetables. The Nurses’ Health Study suggests that frequent consumption of fruit may cut the risk of colorectal adenomas (precancerous polyps). In a recent British Journal of Nutrition, investigators say eating more vegetables “probably reduces the risk of colorectal and stomach cancer.”

Fiber may explain some of the benefits from plant foods. Our ancestors consistently ate a diverse range of plants that may have contributed up to 100 grams of dietary fiber daily; most Americans today don’t get the recommended 20 to 35 grams a day.

Dried legumes contain complex carbohydrates that raise blood sugar slowly, another factor that may help protect against colorectal cancer. The recent Polyp Prevention Trial “suggests that adding a significant amount of dry beans to one’s existing diet has a strong protective effect against recurrence of precancerous polyps,” says Elaine Lanza, PhD, at the National Cancer Institute.

Onion and garlic also appear useful in fighting colorectal cancer, as do members of the cabbage family. One small clinical trial finds the consumption of broccoli and Brussels sprouts increases urinary excretion of potentially cancer-causing substances in well-done meat, for example. Several case-control studies have associated lower intake of cabbage family, or cruciferous, vegetables to diagnoses of colorectal cancer.

don’t forget supplements
A multivitamin containing folate, selenium, and vitamin C is useful. In addition, “calcium may be protective against colorectal cancer development,” finds the Shanghai Women’s Health Study. “An insufficient vitamin D supply might act as a cofactor in colorectal carcinogenesis,” say German investigators.

Experimental research suggests that diallylsulfide (from garlic), lycopene (from cooked tomatoes), and theaflavin (from black tea) may protect against colorectal cancer. Several studies with aged garlic extract (AGE) show particular promise. One clinical study of people with adenomas finds that AGE supplement decreased the size of these growths with minimal side effects. Garlic appears to support DNA repair, inhibiting both cancer growth and inflammation—in addition to many other beneficial activities in the body.

Approved by Germany’s Commission E for liver toxicity, milk thistle contains silibinin, which has chemopreventive responses against colorectal cancer. In addition, “various probiotic species have demonstrated immune-enhancing and antitumor effects,” says Michael Murray, ND, who recommends supplementing the diet with beneficial bacteria Lactobacillus acidophilus and Bifidobacterium bifidum to help reduce the risk of colon cancer. }

A Healthy Lifestyle
Overweight is a risk factor for colon cancer in men, and the EPIC trial strongly links larger waist circumference, an indicator of abdominal obesity, with colorectal cancer in both sexes. High glycemic foods, which tend to be high in calories and low in fiber and nutrients, appear to increase colorectal risk among obese women. Maintain a healthy body weight with exercise, which also helps lower the risk of this cancer.

selected sources

• “Aged Garlic Extract Inhibits Angiogenesis and Proliferation of Colorectal Carcinoma Cells” by N. Matsuura et al.
• “Aged Garlic Extract Has Potential Suppressive Effect on Colorectal Adenomas in Humans” by Shinji Tanaka et al., Journal of Nutrition, 3/06
• “American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention” by Lawrence H. Kushi, ScD, et al., CA Cancer J Clin, 2006
• “Body Size and Risk of Colon and Rectal Cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC)” by T. Pischon et al., Journal of the National Cancer Inst, 7/5/06
• “Dietary Intake of Calcium, Fiber, and Other Micronutrients in Relation to Colorectal Cancer Risk: Results from the Shanghai Women’s Health Study” by A. Shin et al., International Journal of Cancer, 12/15/06
• An Evidence-Based Approach to Dietary Phytochemicals by Jane Higdon, PhD ($59.95, Thieme, 2006)
• “Evolutionary Perspective on Dietary Intake of Fiber and Colorectal Cancer” by J. D. Leach, European Journal of Clinical Nutrition, 1/07
• “Fruit and Vegetable Consumption and Colorectal Adenomas in the Nurses’ Health Study” by K. B. Michels et al., Cancer Research, 4/1/06
• How to Prevent and Treat Cancer with Natural Medicine by Dr. Michael Murray, Dr. Tim Birdsall, Dr. Joseph E. Pizzorno, and Dr. Paul Reilly ($16, Riverhead, 2002)
• “Onion and Garlic Use and Human Cancer” by C. Galeone et al., American Journal of Clinical Nutrition, 11/06
• “Physical Activity, Obesity, and Risk of Colon and Rectal Cancer. . .” by S. C. Larsson et al., European Journal of Cancer, 10/06