Testing for colon cancer is important, but prevention is the first and best defense.

by John R. Lee, M.D. and Virginia Hopkins

Some years ago, Katie Couric, then co-host of NBC’s Today show, elevated public awareness of colon cancer. Understandably upset by her husband’s death from colon cancer at age 42, she became a powerful advocate for early detection and prevention of the disease. She even had her own colonoscopy broadcast live on the Today show to emphasize the often-heard litany that early diagnosis and timely surgery can cure colon cancer and greatly reduce its death rate. From this, the following syllogism has emerged:

• Some 150,000 people per year are diagnosed with colon cancer and 55,000 per year die of it. Colon cancer rates are steadily rising.
• Early diagnosis (prior to symptoms) could save 90 percent of them.
• Therefore, everybody should undertake early diagnostic screening tests.

If one waits until suggestive symptoms occur (blood in the stool, irregular bowel movements, pain, weight loss), the colon tumor is likely to be advanced, and cure much less likely.

The problem is that the population at risk involves 200,000,000 people, and the best early diagnostic test is by flexible colonoscopy that costs $1,000 per test. Ideally, the test should be performed yearly for best results. The annual cost would be $200,000,000,000 ($200 billion per year). This is, to say the least, a bit unrealistic, which is why the various organizations that create medical standards recommend a colonoscopy at ages 50, 60 and 70.

Obviously what is needed is a better, less intrusive, less expensive screening test for colon cancer. The fecal occult blood test (FOBT) can detect hidden blood in the stool, one of the first symptoms of colon cancer, and they can be done at home once a year, more if you have colon cancer in your family. But by far our best option is prevention. Fortunately, we know a lot about prevention. Diet is probably most important. Let’s take a closer look.

Eating to Prevent Colon Cancer
Colorectal cancer is the third leading cause of cancer death and the third most common cancer in both sexes in the United States. This form of cancer doesn’t get the media attention that, for example, breast cancer does, but it’s more common and just as deadly. Even when it doesn’t kill, the consequences of bowel surgery can compromise quality of life. It’s worth it to make the simple lifestyle changes that can help prevent this cancer—and will help prevent other cancers, heart disease and diabetes in the process!

In a nutshell: to prevent colon cancer we need to increase our fiber intake, eat a variety of fresh vegetables, maintain good levels of antioxidants, avoid processed foods, drink plenty of good water, and get some exercise. All of these factors have shown up again and again as preventive in studies of colon cancer. Exercise has been shown to prevent colon cancer more than any other cancer.

Fiber Keeps the Colon Clean and Moving
The colon is also known as the large intestine, and it is the last area of the digestive tract that waste matter passes through before elimination. It’s where your body reabsorbs water and minerals for recycling, and where it absorbs vitamin B12, as well as the fat-soluble vitamins A and E. The bacteria in the colon manufacture vitamin K, which plays a role in blood clotting. Fiber is what keeps all of these processes moving along in the bowel.

Fiber refers to the indigestible residue of plants. It consists of complex carbohydrates that we are unable to digest. They encompass a wide variety of molecular structures that differ in their degree of solubility in water. They add to the bulk of bowel contents and stimulate the passage of waste matter through the colon. Shorter transit times (time of ingestion of food until its elimination via defecation) are related to decreased incidence of colon cancer. In other words, constipation increases your risk of colon cancer, and fiber prevents constipation. Drinking plenty of water also helps prevent constipation.

Until the past six or seven generations, humans ate a diet filled with vegetable and grain fiber. With industrialization our diets changed radically: the processing of foods for commercial sale resulted in the loss of much of the fiber, especially of grain foods. Comparing the illnesses occurring in industrialized and non-industrialized populations, it is apparent that many common illnesses rarely occur in less industrialized areas that eat high fiber diets. Such illnesses include diabetes, constipation, diverticulitis, colon cancer, heart disease, obesity, gall bladder disease and gallstones, pancreatitis, hiatus hernia, appendicitis, hemorrhoids, varicose veins, and even breast cancer. There is an unmistakable epidemiologic relationship between these diseases to low dietary fiber.

Fiber reduces the conversion of primary into secondary bile acids, which are potential cancer promoters; it absorbs more bile acids and dilutes them within a larger stool mass, thus protecting against colon cancer. With fiber, the bile itself is more soluble and less likely to form gallstones; similarly, fiber protects against pancreatitis by preventing biliary sludge.

Fiber reduces fat absorption and lowers cholesterol levels. It even helps lower excess estrogen by speeding up transit time, thus reducing the likelihood that estrogen will be recirculated back into the body.

What’s Your Transit Time?
A good way to test your need for more fiber is the bowel transit time test. Bowel transit time is the time it takes for food to travel from ingestion to exit. All you need to do is eat some food that can serve as a marker when it appears in the stool.

Fresh corn on the cob is one such food; we digest the starch within the kernels but not the kernels themselves, which will be visible in the bowel movement when they are passed. Simply eat some corn and watch your bowel movements until you see the kernels. That is your bowel transit time. A healthy transit time is 18 to 24 hours. In the U.S., common bowel transit times are found to be two to three days, a good indicator of the need for more fiber and water in the diet.

Nutrients and Colon Cancer
Fiber isn’t the only thing you eat that affects your colon cancer risk. A deficiency of some nutrients can also predispose one to colon cancer.

Antioxidants protect against all types of cancer and all of the chronic degenerative diseases that plague Western cultures, such as heart disease, arthritis and diabetes. Your first source of antioxidants should be fresh fruits and vegetables. A good multivitamin can give you added protection. The most important antioxidants are vitamin C (take 1,000 mg daily), vitamin E (400 IU daily), and vitamin A (take 5,000 to 10,000 IU daily).

Other types of antioxidants can be found in the bioflavonoids found in fruit, especially berries, and supplements made from grape seed extract, quercetin, and green tea extracts. Again, these types of supplements, as powerful as they can be, are no substitute for eating fresh fruits and vegetables.

The trace minerals zinc (10 to 15 mg daily) and selenium (200 micrograms) daily, are also powerful antioxidants, and are essential to the health of the colon. Studies have repeatedly linked selenium deficiencies to colon cancer. One study showed a 40 percent reduction in new colon cancer cases in populations who took selenium supplements. Onions and garlic are a great source of selenium.

Calcium is another mineral that has been repeatedly shown to have a beneficial effect on the colon. It is thought to help prevent colon cancer by binding with bile salts and fatty acids that can damage the colonic epithelium and enhance cell proliferation. I’m not a big fan of mega-doses of calcium, but 300 mg daily combined with at least 150 mg of magnesium should confer protection for colon cancer. Milk, while it is a good source of calcium, should be avoided by adults since it often causes a chronic inflammation of the gut that potentially increases the risk of cancer.

Vitamin D is essential to good colon health, and sunshine is the best place to get your daily dose. Vitamin D is so essential to preventing colon cancer, that the risk of getting it is doubled in those who have the lowest levels. People who can’t get outside much or who live in northern latitudes can take up to 2,000 mg daily, although if you take that much get a vitamin D test after a few months.

Folate (folic acid) is a B vitamin that is well known for preventing birth defects, and I recommend it for preventing and treating cervical dysplasia. The Harvard Nurses’ Study showed that women who supplemented with folate long-term have a significantly reduced risk of colon cancer. A good multivitamin will contain 400 mcg (micrograms) of folic acid.

Probiotics are the beneficial bacteria found in the colon. There are at least 400 species of these “good” bacteria, and hundreds of billions of them live in your large intestine. They keep “bad” bacteria in check, and help process waste as it moves through the large intestine. A lack of probiotics, usually caused by taking antibiotics that indiscriminately kill off good and bad bacteria, can lead to inflammation in the bowels, gas, constipation, and generally poor digestion.
If you take an antibiotic, follow it up with a week of eating yogurt or kefir daily, which contain live cultures of the probiotics (it should say on the container that it contains live cultures), or you can take a probiotic supplement, easily found at your local health food store.

It is difficult to imagine a more cost-effective way of reducing the risk of colon cancer (and degenerative diseases in general) than to return to a high fiber diet and eat plenty of fresh fruits and vegetables. I can think of no better example of the axiom that prevention is far better than treatment.

Garland C, Barrett Connor E, Rossoff A et al, “Dietary vitamin D and calcium and risk of colorectal cancer: 19-year prospective study in men,” Lancet, Feb 9,1985. v.1 (8424) p. 307-309.