I hear about fiber, antioxidants, vitamin D, and fats in the news and their relation to colon cancer. What is your opinion of this information, and what are the steps that I can take to limit my risk of colon cancer?
This is an excellent question, as colon cancer is something that most adults over the age of 40 should be thinking about. Conventional medicine has done an excellent job of their watch and wait approach, recommending screening colonoscopies usually after the age of 50. If the disease is caught early by this approach, the cancer can be removed before it has spread.
From a naturopathic and preventative standpoint, watching and waiting is probably not good enough, especially for those patients who are at known risk (certain genetic conditions, family history, and a diagnosis of either Crohn’s disease or ulcerative colitis). For these patients at risk, using the watch-and-wait approach is akin to the following example: if I told you that a burglar was going to come into your house within the next 5 years, a watch-and-wait approach would be to onlycheck the front and back every day or so to make sure the burglar hasn’t arrived yet. It makes much more sense to definitely check for arrival, but to also do everything possible to make it less likely or more difficult for the burglar to enter. Thus getting the security system up (immune system), cleaning up the garbage so the house is not looking dilapidated (detoxification) are also important components.
In general, for all patients, an assessment of their immune system and their toxic burden can be important in cancer prevention. From the toxin standpoint, both heavy metals and pesticides are associated with increased rates of most cancers. Walter Blumer MD in Switzerland did a retrospective study (Journal of Advancement in Medicine, 1989) where he sent his “detoxification” patient records to the University of Zurich for analysis of cancer rates compared to a matched, “non-detoxified” group of patients. The analysis found an astonishing 90% reduction in cancer in the group treated with heavy metal detoxification. This number is so high likely because Blumer was practicing in an area with high traffic and known lead exposure, and lead is considered by the EPA to be a probable carcinogen.
While to most patients it would be obvious that cleaning up the system, and keeping the immune system optimized would go long ways to overall health, most of what we hear about in the news is related to single compounds, such as green tea preventing colon cancer, or fiber being useful in some studies and not in others. I’ve commented below on the most common misconceptions about colon cancer prevention, and what some actual useful steps are.
This is a very eloquent theory that all cancers, aging, and for the most part, any disease is caused by excess free radicals which cause oxidative damage. It is so encompassing of all diseases that it could be compared to the physicist’s Holy Grail of the Theory of Everything, which links quantum mechanics and relativity. This theory states that it is oxygen and its related free radicals that cause damage to tissue in inflammation, damage to genes that control growth (leading to cancer), and damage to tissues in chronic diseases. Thus, if humans overload their bodies with antioxidants, then we can protect ourselves from this damage and specifically, prevent damage to genetic tissues, preventing cancer. After all, most of the largest trials have shown that fruits and vegetables prevent cancer and age-related diseases, and fruits and vegetables are loaded with antioxidants.
Unfortunately, the weight of the evidence strongly indicates that this theory is NOT true.
The reasons why the idea that excess free radicals are a modifiable cause of cancer, and that taking plenty of antioxidants to prevent this onset of cancer (such as vitamin E, beta carotene, other carotenoids), is too complex to go over in this newsletter. Its relation to colon cancer, however, is as follows.
Colon cells which have lost their ability to control growth usually still have the ability to commit cell-suicide through a process called apoptosis. This process is heavily dependent on the generation of large amounts of oxygen free-radicals, including hydrogen peroxide, singlet oxygen, and superoxide anion. In short, the consumption of large amounts of single nutrient antioxidants, and the carotenes in particular, has the ability to block this cell-suicide. Thus, overconsumption of single antioxidants theoretically blocks the normal free radical mediated process of cell suicide.
What’s the reasoning specific for colon cancer?
In the International Journal of Cancer June 2006, the Alpha tocopherol, beta carotene cancer prevention study was analyzed with respect to iron. The findings were quite unexpected by most as many were expecting iron, with its pro-oxidant abilities, to be associated with increased cancer. In fact the opposite was found and higher levels of iron were associated with decreased risk of colon cancer.
This is very understandable because colon cancer cells need oxidants, or need to be susceptible tonormal amounts of oxidants in order to commit cell-suicide.
Iron makes the following reaction occur:
Hydrogen peroxide --> hydroxyl radical + hydroxide, or H202 --> OH* + OH-
The OH* is one oxidant responsible for cell-suicide in cancer cells.
Vitamin D, perhaps my most often recommended nutrient for colon cancer prevention (after testing the blood levels to find an optimal dosage), has the best evidence for colon cancer prevention. The evidence falls under epidemiological data (where populations with higher vitamin D have less colon cancer), treatment data (where vitamin D and its analogues are used in treating colon cancer), and mechanistic data.
The mechanistic data is particularly interesting. Vitamin D appears to have general anti-cancer actions through stimulating cells to differentiate and specialize, whereas aggressive cancer cells tend to revert to a non-specialized state. Vitamin D also has clear effects on the immune system, particular the aspects of the immune system that attack cancer. This part of the immune system is generally only effective against cancer in its early stages, when we are only talking about a few cells. This is where the real prevention happens.
The other interesting aspect about vitamin D and its relation to colon cancer is that there is data that indicates vitamin D actually stimulates colon cells to be more susceptible to free radical and oxidative damage. As we know, this is particularly important for cancer cells because it is one of the main mechanisms in which cancer cells die. Thus, sufficient vitamin D makes colon cancer cells more sensitive to suicide mechanisms that use hydrogen peroxide, iron, and free radicals. In other words, the nutrient that has some of the strongest evidence for colon cancer prevention is not an antioxidant, but a nutrient that has pro-oxidant action!
While the free radical theory of cancer genesis, and the corresponding theory that antioxidants, carotenes, and vitamin E would protect from cancer is a great idea, large studies have shown that this is not the case. One of my favorites is the Polyp Prevention Study Group, which was a 4 year clinical trial that studied the use of vitamin C, E, and beta carotene to see if there was a reduction in colon polyps (which can be precancerous). This trial was completed in 1994 and found no reduction in polyps with the use of the antioxidants. The Australian Polyp Prevention Study found 1.5 times more colon cancer in the group that used 20 mg beta carotene.
Thus, while antioxidants as a supplement probably do not help prevent colon cancer, high doses of vitamin D3 (blood levels must be checked to find the right dosage, as it can range from none necessary to 4000 IU daily) is a great measure to take. Furthermore, a diet rich in fruits and vegetables has repeatedly been found to be protective. It just probably isn’t from the antioxidant action or the antioxidant vitamins found in the fruits and vegetables. The protective effect is likely from the combination of the plant chemicals with known anticancer action, separate from their antioxidant action.
Folic acid seems to be useful in chemoprevention of colon cancer, but the largest study, the Nurses Health Study, indicates that the risk reduction is only statistically significant (and the risk reduction is quite large also!) after 15 years of continuous use. This study compared those who had >400 mcg folic acid to those who had <200 mcg, so the dosage is quite small. When I use folic acid as a supplement, the dosage is much larger, but it still likely has to be long term supplementation in order to get benefit. There are many other trials on folic acid on colon cancer prevention, and there is data going both ways. Over all, it is such a safe nutrient, and it has effects on lowering homocysteine for cardiovascular health, that I think it can be a good idea in patients at risk.
As mentioned above, iron is important in prevention of colon cancer. While some studies do not differentiate between iron loss in chronic bleeding from colon cancer and actual iron deficiency leading to increased diagnosis of colon cancer, other studies found that low iron correlated with increased incidences of non-bleeding, possibly precancerous polyps. Copper deficiency also has strong associations with colon cancer incidence, and copper participates in the generation of free radicals also. Neither of these should be supplemented though unless they are found to be deficient through testing.
Steps for those at risk of colon cancer
1. General blood chemistry screen and comprehensive metabolic profile to assess for iron deficiency, other problems. History and physical exam to assess for any significant immune system issues.
2. 25-OH vitamin D3 blood test: this is vital to seeing what an ideal dosage of vitamin D3 is needed, if any, to achieve blood levels that are not just protective against bone loss, but preventive against colon cancer.
3. Hair analysis and provoked metal detoxification challenge: in those over 40 to assess for significant increased body burden of toxic metals. This is much better than a simple blood mercury and blood lead, which are usually only indicative of acute exposure. Remember, heavy metal toxins are likely human carcinogens, and there is evidence that removal will lower cancer risk.
4. Consider folic acid, calcium, green tea, curcumin, diet rich in fruits and vegetables, diet low in red meat and preserved meats. The ideal plan is also based on the blood chemistry and metabolic profile, as this can give hints as to the ideal type of diet for a particular person’s metabolism.
5. Aerobic exercise.
6. Screen for food allergy through either blood ELISA/RAST test, and/or intradermal (skin) injection, or sublingual (under the tongue) allergen challenge. Groups with inflammatory bowel diseases, such as Crohn’s and ulcerative colitis, are at known elevated risk for colon cancer. It is a stretch to say that the same risk is present in patients with undiagnosed food allergies, but remember it is the inflammation in the diseases that gives the increased risk, so if a patient’s history and exam indicate either inflammation or allergies, then work up for food allergies can help.
7. And of course, the standard “watch-and-wait” colonoscopies and fecal occult blood tests.