The use of sigmoidoscopy and colonoscopy is now gaining widespread acceptance among physicians, patients and even insurance companies. While these techniques are beneficial and important, I’d like to focus on whether nutrition may play a role in colon cancer prevention. Our goal as health care providers should be to intervene at the earliest possible step, by giving each person the best chance of preventing this disease.

It is important to briefly discuss some theories about colon cancer formation. It seems that many people with colon cancer have one, or a series, of genetic abnormalities that may predispose to the development of colon cancer. These genetic malfunctions may be inherited, as is the case of people with family histories of colon cancer, or induced by damage to the DNA of the colon cells.

The cause of the latter may be primarily due to oxidative stress from the environment or diet, with a complex relationship being the body’s response to what we eat. What we do know is that most colon cancer start as polyps, small growths of precancerous tissue, that if left in place will go on to develop cancer. Colon cancer screening with colonoscopy is used to remove polyps before they become cancers, thus preventing it.

But is there a way to prevent the change to cancer, or even the formation of polyps? Intuitively, we can surmise that this would need occur at the level of DNA, before any mutation. We know that DNA is damaged by oxidation, so this is certainly one possibility. Additionally, many of the body’s enzyme reactions that help repair DNA are dependent upon certain nutrients, including vitamins and minerals. Thus, if deficiencies or a relative lack occurs, one may be more susceptible to the various factors, which lead to the development of cancer. So it may very well be that what we put into our intestinal tracts holds the key to prevention of this dreaded disease.

With this background in mind, let’s now look at the available evidence:

1. Fiber. It was long thought that a high fiber diet diminished one’s risk of colon cancer. Most evidence was epidemiological, from population studies. The interaction with dietary fat was also thought to be important- a reduction in dietary fat with increased fiber.

The issue of whether colon cancer incidence can be decreased by dietary fiber is still being debated, with some recent literature shedding doubt on the subject. Still, the majority of the evidence favors a high fiber diet. Since fiber has so many other beneficial effects (bowel regularity, decreasing serum cholesterol etc) my recommendation is to use get plenty of dietary fiber, and if you are not close to 25 or 30 grams/day, use a psyllium based supplement. Why psyllium? It has beneficial properties that help promote stool bulk, absorption of bile salts (which may be a promoter in colon cancer formation) and possibly elimination of other toxins. Additional benefits include a feeling of fullness, which may promote weight loss, and a well-documented reduction in serum cholesterol.

2. Dietary fat intake. The evidence is pretty clear that increased colon cancer rates occur in populations with increased dietary fat intakes. This would be most strongly associated with saturated fat, and several studies have specifically pointed to red meat. However, the mechanism may actually be increased bile acid production (see above), so the exact mechanism is not known. While eating some red meat is likely safe, one should probably not consume a diet high in saturated fat or red meat, for this and other health reasons.

3. Calcium. Increased levels of dietary and supplemental calcium have been shown to decrease polyp formation in susceptible populations, and decrease the experimental markers of polyp formation. Since calcium intake is vital for the prevention of osteoporosis (in both men and women), one should make sure they have a daily total calcium intake of 1200 mg for men and 1500 mg for women. This includes both dietary and supplemental forms. The form of calcium is also important, and the most well studied and effective supplemental form is calcium citrate malate. Your supplement should contain this form, or you may not be getting what you are paying for. Vitamin D supplements will enhance absorption, and it is essential for osteoporosis prevention. In addition, there may be some additional effect of Vitamin D on colon cancer prevention, but this is not at all clear at the present time.

4. Folic Acid. This vital nutrient has come to light recently in a number of areas. Maternal deficiency leads to neural tube defects in infants, and supplementation prevents this complication. Folic acid also can decrease homocysteine levels and reduce the risk of coronary artery disease. Pertinent to our discussion is the recent report from the nurse’s health study that indicated that supplemental vitamins could decrease risk of colon cancer. Specifically, those women with folic acid consumption > 400 mcgm/day had the lowest incidence of colon cancer. Numerous scientific studies have shown that folic acid is a key part of the bodies enzymatic defense system to help prevent or repair damage to DNA. It is widely believed that damage to DNA in colon cells arises on both a genetic basis and through environmental triggers. It is believed that folic acid may stabilize the DNA, making it less susceptible to damage. The bottom line: for the prevention of heart disease and probable decrease in the risk of colon cancer, supplement your dietary intake of folic acid to the level of 800 mcgm/day.

5. Antioxidant vitamins. I’m going to lump together a broad category of vitamins that we call antioxidants. These include A, C and E. It is important to understand that this is a complex area, because there are a variety of different forms and preparations of each vitamin, and studies that have been done are really inconclusive. Additionally, my criticism of the currently available studies is that they may have tried to pull apart this whole group to find out which particular one is active, when in fact there are documented synergies between the antioxidant group that simply cannot be ignored. In my opinion, none of the studies available show a clearly detrimental effect, many are positive, and some are neutral. Again, taking this health concern into consideration with all others, a diet rich in antioxidant vitamins is beneficial, and I believe supplementation will enhance any possible benefits.

6. Green Tea. Although not a vitamin, this agent has been getting a lot of press also, and some of the studies are most compelling. There are several epidemiological studies indicating that one of the reasons for a lower colon cancer incidence in certain countries may be related to consumption of green tea. Additionally, experimental models using human colon cancer cell lines have indicated a reduction in growth and an inhibition of colon cancer cells in some cases. The active ingredient in green tea appears to be epigallocatechin. While this topic clearly needs more study, the body of literature that is developing around the benefits of green tea is growing, and is very compelling.

7. Exercise. Exercise promotes bowel regularity, generally makes one more vigilant about what they are eating, and may have some direct effects on the incidence of colon cancer. It is so intertwined with other parts of a healthy lifestyle, that it may be difficult to determine if it has beneficial effects on it’s own. Nonetheless, it’s an important part of maintaining vigorous health.

8. Aspirin and NSAIDS. Aspirin has been shown in some studies to decrease the risk of developing colon cancer. It is not clear if this was a direct effect, or if it is related to the earlier detection because aspirin caused tumors or polyps to bleed, which allowed detection. Some theoretical effects on aspirin’s effect on the cyclooxygenase system may also contribute, but nothing has been clearly established. Clinical trials are going on with the use of celebrex, a Cyclooxygenase-2 (COX-2) inhibitor to prevent colon adenomas in at risk populations.

9. Omega 3 fatty acids. These dietary constituents are most commonly found in fish oils, and have been widely studied in a variety of diseases. Some epidemiologic data have shown reduced colorectal cancer rates in those individuals with high consumption of fish oils. Additionally, there is some experimental data showing decreased proliferation of colonic cells (i.e. slower growth), which may have a beneficial effect. No prospective studies are yet available.

10. Curcumin (Turmeric) is a traditional spice which contains a phenolic compound called curcumin. Curcumin has been shown to have significant potential as a chemopreventive agent for cancer, especially colon. It has been shown to prevent colon adenoma formation in mice by modulating lymphocyte-mediated immune functions. In one study, rats fed a diet containing curcumin showed a dose-dependent decrease in colon cancer. Studies using human colon cancer cell lines have also demonstrated an inhibition in the progression of the colon cancer sequence, via inhibition of cyclo-oxygenase as well as cyclo-oxygenase independent mechanisms.Studies on basal cell cancer as well as metastatic melanoma have also yielded promising results.

11. Selenium. I’ve actually saved the best for last. Selenium is a necessary cofactor for an enzymatic reaction in the body that is vital for proper immune system function. There are many areas of the US that have soil that is selenium deficient; hence the crops grown there are also deficient. Numerous studies have documented that people with low selenium levels have a higher incidence of cancer. Additionally, one large study of 1300 patients found that supplementing the diet with 200 mcgm/day in the form of selenomethionine decreased the risk of not only colon cancer, but lung and prostate cancer, by upwards of 40%! This was a well-done study published in the Journal of the American Medical Association (JAMA) in 1997. I believe there is ample evidence to recommend selenium as a dietary supplement.

In summary, there is a growing body of literature supporting the fact that nutrition plays a major role in colon cancer formation, and that supplementation of the diet with certain nutrients may diminish this risk.

While all the evidence is not clear-cut, what I’ve presented above is at the very least compelling. Additionally, dietary supplementation as I will outline below may have additional benefits in general health, specifically for coronary artery disease and other vascular disease. Our food supply has changed, so please don’t think that eating a healthy diet alone will provide you with the OPTIMAL level of nutrients.

Also, there is a difference between the Recommended Daily Allowance (RDA) and the optimal dosage. The RDA is the level necessary to prevent deficiency, and makes no effort to determine the level of nutrients needed to maintain optimal health (a perfect example is folic acid).

What I have presented is the optimal dosages and forms that have been used in scientific studies. I hope that one day we will be able to present absolute data on this topic, but until then we have to use the weight of the evidence. And don’t forget to ask your doctor about appropriate colon cancer screening.

Dietary supplement recommendations
1. Psyllium based fiber supplement and high fiber diet
2. Low fat diet
3. Calcium 1200 to 1500 mg/day (calcium citrate malate is best form)
4. General antioxidants Vitamin A as beta carotene 12,000 units/day, Vitamin C (as Ester-C) 1000 mg/day, Vitamin E (as natural mixed tocopherols) 500 units/day.
5. Folic Acid 800 mcgm/day
6. Selenium (as selenomethionine) 200 mcgm/day
7. Curcumin 400 to 600 mg two to three times each day.
Optional, may also be beneficial:
8.Green Tea: 5 cups day or supplemental extract standardized for epigallocatechin

Where to find great prices on vitamins
Based on my Internet shopping, I’ve identified a few websites where you can get some of the products you may need:

vitacost.com : absolutely the lowest prices on the Internet, and many top quality brands are available. Selection is somewhat limited, but growing. They have the best line of nutriceuticals available for specific diseases (ex. Arthripower for arthritis, Occupower for macular degeneration and Cardiolift for heart disease) from a company called Nutraceutical Sciences Institute (NSI). NSI also has the best all around antioxidant supplement (Synergy 2000) and one designed just for women (Synergy 3000). Great encyclopedia of medical problems

vitaminshoppe.com : large selection, just about every brand and product, mediocre prices. They occasionally run specials from a particular company, so you can check monthly for the best price, but still rarely lower cost than vitacost.

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