On the Prevention and Treatment of Colon Cancer

by David Bennett

This article is designed to present some basic research on preventing and treating colon cancer, one of the most common cancers facing westerners. This article is designed to help you research how to prevent colon cancer, but is not intended to diagnose or treat any condition. This is a work-in-progress. Please check back. Currently, all sources are listed at the end of each section. Later they will all be laid out as endnotes.

Symptoms of Colon &/or Rectal Cancer

Symptoms of colorectal cancer include: rectal bleeding, abdominal pain, changes in stool size and shape, and unexplained weight-loss. If you have any of these symptoms, see a doctor immediately and schedule a colonoscopy. Even though these symptoms often point to something less serious (like a benign polyp or hemorrhoids), early detection is the key to surviving colorectal cancer!


Calcium's ability to prevent colon cancer is demonstrated by a few studies, although other studies show little benefit. The benefit to Calcium supplementation may be that the mineral helps prevent precancerous changes in the colon, as is indicated below.

One study examined middle-aged white males for 19 years, and found that Calcium and Vitamin D levels were tied to colorectal cancer development. The lower the amounts of calcium and vitamin D, the greater incidence of cancer. Other epidemiological studies in Scandinavian countries showed similar results. Men with the lowest intake of Calcium were three times more likely to develop cancer than those (in the American study) consuming high levels of Calcium. Additionally, two cancer researchers with the Memorial Sloan-Kettering Cancer Center studied colon cells from people at high-risk for colorectal cancer, and found that the cells were dividing more rapidly than normal. Supplementation with 1250 mg of Calcium for three (3) months caused these cells to act more like normal cells, thus possibly reducing the risk of colorectal cancer.

While these studies are positive, others have shown no relation between calcium levels and colon cancer incidence. Nonetheless, consuming 1250 mg/day of calcium has other benefits, even if preventing cancer may not be one of them. Good sources of Calcium include dairy products, green leafy vegetables, and calcium carbonate antacids. However, some nutritionists and physicians view the carbonate source as inferior to other supplemental sources, including gluconate, citrate, and amino acid chelate, which may be absorbed more efficiently.

Baron JA, Beach M, Mandel JS, et al. Calcium supplements for the prevention of colorectal adenomas. N Engl J Med 1999;340:101-7.
Bostick RM, Fosdick L, Wood JR, et al. Calcium and colorectal epithelial cell proliferation in sporadic adenoma patients: a randomized, double-blinded, placebo-controlled clinical trial. J Natl Cancer Inst 1995;87:1307-15.
Heinerman, John, PhD. Dr. Heinerman's Encyclopedia of Nature's Vitamins and Minerals. Prentice Hall Press, 1998.

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Folic Acid

People with ulcerative colitis are at increased risk for colon cancer. In a preliminary report, patients with long-standing Ulcerative Colitis who took folic acid supplements of at least 400 mcg/day had a 62% lower incidence of colon cancer or precancerous changes in the colon, compared with those who did not supplement with folic acid. Although this difference was not statistically significant, the researchers recommended that people who take sulfasalazine (an ulcerative colitis drug that depletes Folic Acid) should supplement with folic acid to possibly reduce the risk of colon cancer.

As dietary folate increases, the risks of precancerous polyps in the colon and colon cancer itself decrease, according to some reports (although other reports suggest no link). In one study, women who had taken folic acid supplements had a statistically significant 75% reduction in the risk of colon cancer, compared with women not taking folic acid supplements, but only when they had been supplementing with folic acid for more than 15 years. In another study, the association between dietary folate and protection from precancerous polyps grew much stronger when use of folic acid supplements was considered (as opposed to studying only folate intake from food), a rare instance when supplements outperform food.

The protection from colon cancer associated with folic acid has been reported to occur more in alcohol drinkers than in nondrinkers. This may be because folate seems to reverse DNA damage caused by alcohol consumption.

Of note, cancer patients taking the chemotherapy drug methotrexate must not take folic acid supplements without the direction of their oncologist.

Good Sources of Folate include (mcg/100g serving):
Garbanzo Beans (Chickpeas): 557 mcg
Lentils: 433 mcg
Sunflower Seeds: 238 mcg
Instant Coffee: 327 mcg
Peanuts: 240 mcg
Spinach, raw: 194 mcg
Orange Juice, from concentrate: 155 mcg

Longstretch GF, Green R. Folate status in patients receiving maintenance doses of sulfasalazine. Arch Intern Med 1983;143:902-4.
Lashner BA, Heidenreich PA, Su GL, et al. Effect of folate supplementation on the incidence of dysplasia and cancer in chronic ulcerative colitis. Gastroenterology 1989;97:255-9.
Giovannucci E, Stampfer MJ, Colditz GA, et al. Folate, methionine, and alcohol intake and risk of colorectal adenoma. J Natl Cancer Inst 1993;85:875-84.
Benito E, Stiggelbout A, Bosch FX, et al. Nutritional factors in colorectal cancer risk: a case-control study in Majorca. Int J Cancer 1991;49:161-7.
Baron JA, Sandler RS, Haile RW, et al. Folate intake, alcohol consumption, cigarette smoking, and risk of colorectal adenomas. J Natl Cancer Inst 1998;90:57-62.
Giovannucci E, Stampfer MJ, Colditz GA, et al. Multivitamin use, folate, and colon cancer in women in the Nurses' Health Study. Ann Intern Med 1998;129:517-24.
Giovannucci E, Stampfer MJ, Colditz GA, et al. Folate, methionine, and alcohol intake and risk of colorectal adenoma. J Natl Cancer Inst 1993;85:875-84.
Boutron-Ruault M-C, Senesse P, Faivre J, et al. Folate and alcohol intakes: related or independent roles in the adenoma-carcinoma sequence? Nutr Cancer 1996;26:337-46.
Cravo ML, Pinto AG, Chaves P, et al. Effect of folate supplementation on DNA methylation of rectal mucosa in patients with colonic adenomas: correlation with nutrient intake. Clin Nutr 1998;17:45-9.


In a study published in the Journal of the American Medical Association, the risk of colorectal cancer was directly related to magnesium intake. The higher the magnesium intake, the lower the risk of colorectal cancer. Those women with the highest magnesium intake (255 mg/day and above, which is well below the US RDA) were only 60% as likely to develop colorectal cancer as those in the lowest magnesium intake category. The findings were similar for both colon cancers and rectal cancers.

Good Sources of Magnesium include (mg/100g serving):
Brazil Nuts: 376 mg
Sunflower Seeds: 354 mg
Almonds: 286 mg
Instant Coffee: 327 mg
Dry-Roasted Peanuts: 176 mg

Magnesium intake in relation to risk of colorectal cancer in women. SC. Larsson, L. Bergkvist, A. Wolk, JAMA, 2005, vol. 293, pp. 86--89


Selenium is a powerful mineral in the prevention of most every cancer, not just colon. It is believed that many Americans are deficient in this mineral, because soil levels of the mineral vary significantly. The strongest evidence showing the anticancer effects of selenium comes from a double-blind trial of 1,312 Americans with a history of skin cancer who were treated with 200 mcg of yeast-based selenium per day or placebo for 4.5 years, then followed for an additional two years. Although no decrease in skin cancers occurred, a dramatic 50% reduction in overall cancer deaths, and a 37% reduction in total cancer incidence were observed. A statistically significant 58% decrease in cancers of the colon and rectum was reported.

Good Sources of Selenium include (mcg/100g serving):
Brazil Nuts: 1917 mcg
Tuna, light, in water: 80 mcg
Sunflower Seeds: 79 mcg
Halibut: 47 mcg
Salmon: 47 mcg
Dark-Meat Turkey: 41 mcg

Clark LC, Combs GF Jr, Turnbull BW, et al. Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. JAMA 1996;276:1957-63.

Vitamin D

Vitamin D has been in the news recently as a way to prevent many diseases, including cancer. Many studies indicate that consuming an adequate amount of Vitamin D prevents colon cancer. Another study found that consuming 1100 IU of Vitamin D lowered the risk of getting cancer by 60%. One way to get Vitamin D is from sun exposure, although some experts are cautious to recommend this for fear of increasing the risk of skin cancer (see my article Do Sunlight and Vitamin D Increase Cancer Surivial Time?). Vitamin D is not widely distributed in foods, so supplements may be the safest and cheapest way to get adequate levels of Vitamin D.

Good Sources of Vitamin D include (IU/100g serving):
Atlantic Herring: 1628 IU
Sockeye Salmon, canned, with bones: 763 IU
Milk 1%: 52 IU
Egg, whole, cooked omlet: 29 IU


This article is in development and is posted online while it is being written for the benefit of those needing the information. This is a work in progress.

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