Healthy Choices Protect Against Colorectal CancerAugust 2016
By Caroline Meyers
The American Cancer Society estimates that the majority of colorectal cancers, and subsequent deaths, could be prevented if we applied existing knowledge about this prevalent malignancy.1
Simply making healthy diet and lifestyle choices can reduce the risk for developing colorectal cancer.
With a wealth of research available, too many people continue to needlessly die from this preventable disease.
This article describes strategies available for reducing one’s risk of contracting colorectal cancer, which translates into living a longer, healthier life.
The Most Preventable Cancer
Colorectal cancer (cancer that occurs in the colon or rectum) represents the second leading cause of cancer death in men and women combined in the United States.2,3 According to the American Cancer Society, an approximate 135,000 new cases will be discovered and close to 50,000 deaths will occur in this year alone.4
Despite these statistics, colorectal cancer is one of the most preventable of all cancers. Lifestyle factors play a predominant role in the development of the disease, which means we have a tremendous amount of control over this second-leading cause of cancer deaths.
Cancers in general do not thrive when the body is operating at peak health. This includes active biological systems that work to stop cancer before it even starts by preventing and repairing DNA damage, identifying and destroying abnormal cells, and regulating normal cell growth. The best way to keep these systems in peak condition is through healthy diet and lifestyle choices, as well as incorporating a supplement regimen that includes powerful chemopreventive agents.
The authors of a study published in Clinical Colorectal Cancer said, “Improving the awareness of the population with regard to the benefits of a healthy lifestyle, including a balanced diet associated with exercise, could globally reduce CRC (colorectal cancer) risk.”5
A “healthy lifestyle” can include something as simple as regular brisk walking, which has been shown to reduce colorectal cancer risk by 18%-24%.6,7
The reason why exercise is always near the top of any health-optimization regimen is because increased physical activity significantly improves insulin resistance, and also improves levels of inflammatory mediators and inappropriate growth factors. All of these factors, if left untreated, tend to promote cancer development.5,8
Importance of Diet on Colorectal Cancer Incidence
Even more vital than exercise, diet is known to be one of the most important aspects of reducing colon cancer risk. 9-11 While dietary factors can impact all cancer types, they are especially critical in colorectal cancer because of the function and location of the large intestine (which includes the colon and rectum).
All food and drink that enters the body and has to be eliminated must pass through the large intestine. This exposes cells that line the large intestine to carcinogens that either directly damage DNA, or that increase inflammation, which causes free radicals that also damage DNA.
Eating foods cooked at very high temperatures, as Life Extension Magazine® has warned readers about for decades, can cause the formation of cancer-causing chemicals that damage cells of the large intestine.
Studies show that there are numerous foods (or components of foods) that are associated with increased colorectal cancer risk.6,9,11 These include red and processed meats, preserved foods, saturated fats, high-sugar foods, and refined carbohydrates (“white” starches).
Numerous dietary factors have been shown to have a protective effect against colorectal cancer. These include regular consumption of calcium, vitamin D, fruits, vegetables (especially cruciferous vegetables such as broccoli, cauliflower, and Brussels sprouts), fiber, and fish.6,9
More specifically, regular fish consumption reduces the risk of colorectal cancer by 12%, and eating fish while ingesting more than 20 grams per day of fiber can reduce risk by 25%.6
A glance at the protective dietary factors above reveals that plants and fish products play an especially large role in colorectal cancer prevention. This is due in large part to the abundance of protective molecules that these organisms produce, including vitamins and a host of other biologically active compounds.
While healthy diet is critical, nutrient supplements also provide many compounds shown to help guard against cancer. The use of supplements to reduce the risk of cancer (known as chemoprevention) shows promise for preventing, slowing, and even reversing colon cancer development.
Here is a list of some of the best-studied nutrients in this area:
Higher vitamin D levels are associated with reduced colorectal cancer incidence and deaths. This is likely because vitamin D has immune-supportive functions that can boost the activity of cells that seek and destroy early cancer cells. Vitamin D also reduces the chronic inflammation that can promote colorectal cancer development.12
Studies show that vitamin E, especially in the form of gamma-tocotrienol, reduces colorectal cancer cell growth and even induces tumor cell death.13,14 In addition, vitamin E has strong free radical scavenging properties that may prevent DNA mutations from occurring to begin with.15
Folic acid is important in protecting DNA strands from damage, and has been shown to reduce colorectal cancer risk by 42% in people with inflammatory bowel disease, a group at high risk for this type of cancer.16
Minerals, particularly calcium and selenium, also appear to factor heavily in colon cancer prevention.12 In a large Korean study, people in the highest 25% of calcium intake had an impressive 84% reduction in colon cancer risk, compared with those in the lowest 25% of intake.17 Lab studies reveal that selenium compounds can induce autophagy, a form of cancer cell death in which cells simply destroy themselves. This powerful mechanism is currently being targeted by drug developers.18
Fish oil, rich in omega-3, is a potent inhibitor of inflammation throughout the body, making it a natural fit for colon cancer prevention.19,20 Human studies demonstrate that supplementation with the omega-3 EPA (eicosapentaenoic acid, 2 grams daily for 30 days prior to surgery for colorectal cancer) can reduce the formation of new blood vessels essential for tumor growth, and appeared to produce some increases in overall survival for the first 18 months post-operatively.21
N-acetyl cysteine (NAC) is a strong, natural, free radical scavenger compound, making it appealing for use in cancer prevention of the colon.22 Studies have shown that people at risk for colorectal cancer who took NAC supplements, 600 mg per day, had a 40% reduction in the recurrence of colonic polyps.22 Biochemical and microscopic studies reveal that NAC augments the function of mitochondria (powerhouse of our cells), and produces microscopically detectable changes in early colon cancer in animals.23
As beneficial as they are when taken separately, taking certain nutrients in combination has been shown to have additional value in colorectal cancer prevention. In a large clinical study, the combination of vitamins A, C, and E, along with the element selenium (200 micrograms), reduced the recurrence rate of precancerous polyps by 39%.24 Daily multivitamin use was associated with an 8% reduction in colorectal cancer risk compared with nonusers.25
The Protective Power of Plant-Based Nutrients
Phytonutrients are components of plants thought to promote human health. They help protect plants from dangers such as UV radiation and insect attacks. They also confer protection to those who consume the plants.
Not surprisingly, plant-based nutrients have multiple protective effects against colon cancer. We’ve included a summary of some of the best-studied phytonutrients.
Garlic, especially aged garlic, suppresses the excessive cell proliferation that occurs in the earliest stages of colon cancer. One animal study showed that supplementation with aged garlic extract significantly reduced the development of aberrant crypt foci (precursors of cancer).26 It also reduced the total number of polyps and cancers that formed, a finding that was replicated in humans with a dose of 2.4 mL (approximately half a teaspoon of liquid aged garlic extract) per day for one year.27 Human studies show a 37% reduction in colorectal cancer risk in people with the highest garlic consumption.28
Ginger has effects similar to those of garlic, especially by blocking cell replication and boosting cancer cell self-destruction.29-32 Doses of ginger at 2 grams per day have produced significant favorable changes in the intestinal lining cells of people at increased risk for colorectal cancer.29
Milk thistle extracts, particularly silibinin and silymarin, have numerous mechanisms that help prevent cancers from forming. These include triggering cancer cell suicide (apoptosis), reducing inflammatory changes, and blocking cell replication. Importantly, they also help prevent the spread of existing cancers by reducing the production of protein-melting enzymes that cancer cells use to invade and metastasize.33-35
Cruciferous vegetable extracts are those derived from broccoli, cabbage, Brussels sprouts, and related plants. These extracts are rich in molecules called isothiocyanates, which have been shown to promote cancer cell suicide and inhibit colorectal cancer development in animal and lab models.36,37 Indole-3-carbinol (I3C) is another component of these plants that has been shown to reduce inflammation and attenuate colorectal tumor development in animal models. Human studies show that those with higher levels of indole-3-carbinol have significantly lower colorectal cancer risk.38-41
Modified citrus pectin is a gel-like compound extracted from citrus peels that has direct tumor-killing effects on cancer cells. More importantly, animal studies show that it significantly prevents the spread of colorectal cancers to other parts of the body.42,43 This effect arises from pectin’s ability to bind to and block adhesion molecules that metastatic tumor cells use to stick to, and invade, distant tissues.42,43 (Modified citrus pectin is usually taken by those already stricken with cancer. It is not considered a preventive.)
Coffee is rich in numerous bioactive molecules that appear to have anti-cancer properties, such as inducing cancer cell suicide.44,45 Studies show that people with the highest coffee consumption (more than 3 cups per day) have a 33%-79% reduction in their risk for colorectal cancers compared to the lowest consumers.46,47
Polyphenols Reduce Cancer Risk
Among the largest group of plant-based nutrients with demonstrated cancer-fighting potential is the polyphenol family.48 Numerous epidemiological studies offer solid evidence that diets rich in polyphenols result in significantly lower incidence for many kinds of cancer—including colon cancer.49,50
Three of the most potent polyphenols with colon cancer-preventive effects are resveratrol, quercetin, and curcumin.
Resveratrol is found in grape skins and other red-pigmented foods. It is one of the best-known polyphenols—and for good reason. It has actions against multiple stages of the cancer-development process that make it a potent chemopreventive agent. Resveratrol is a gene-modifying agent that enhances cells’ resistance to oxidant- and inflammation-promoting stresses.51 It has multiple, complementary effects on colon cancer development, including switching “on” a tumor suppressor gene that gets switched “off” early in carcinogenesis and inhibiting genes for invasion-promoting proteins.52 Preliminary human studies show that oral doses of resveratrol, ranging from 500 to 5,000 mg per day, achieve levels in the intestine consistent with anti-carcinogenic effects.53,54 For people ingesting a wide variety of polyphenols from their healthy diet and supplements, lower doses (100 to 250 mg per day) of resveratrol may be all that is needed.
Quercetin is found in apples and onions. It has been shown to stop the cancer cell replicative cycle and is strongly associated with a reduction in inflammatory molecules that promote cancer development.55,56
Curcumin is what gives the Indian spice turmeric its yellow color. This phenolic compound has an impressive suite of anti-cancer properties that prevent or fight cancer at multiple stages of the development process.57 It blocks inflammation that promotes cancer progression, it stops the cancer cell replication cycle in its tracks, it increases the rate of cancer cell self-destruction, and it prevents tumor cells from developing invasive and metastatic potentials.58-60 In addition, lab studies reveal its ability to inhibit the recently-discovered cancer stem cells, which hide in tissues and are a major cause of cancer recurrence after treatment.61 And a human clinical trial showed that curcumin, 4 grams per day for 30 days, significantly reduced the number of precancerous lesions found on colonoscopy, compared with controls. 62 (Those obtaining nutrients from healthy diets and supplements usually need only 400 mg per day of highly absorbable curcumin.)
Drugs that Prevent Colorectal Cancer
Several pharmaceutical agents are showing signs of effectiveness in preventing colorectal cancers. Aspirin has been associated with a reduction in colorectal cancer incidence and deaths, even at the low doses used for cardiovascular disease protection (75 to 100 mg per day).63 One very large, long-term study has shown that regular aspirin use is associated with as much as a 19% reduction in colorectal cancer rates.64 Unfortunately, most doctors overlook aspirin’s cancer-preventive properties.
Metformin is an antidiabetic drug with a longstanding safety record and a suite of actions more similar to natural supplements with multiple targets than to most single-targeted drugs (indeed, it is derived from the French Lilac tree). Because diabetes is a major risk factor for colorectal cancer, there has been great interest in metformin for cancer prevention, both in diabetes patients and in others.65 A study demonstrated that metformin use is associated with a 10% reduction in the incidence of colorectal cancers and a 32% increase in survival, compared with nonusers.66 In another study, metformin at a dose of 250 mg daily showed a 40% reduction in the prevalence of precancerous adenomas.67
Colorectal cancer remains the second leading cause of cancer deaths.
Colorectal cancer risk may be greatly reduced through a combination of lifestyle and diet interventions.
A number of nutritional supplements have demonstrated colorectal cancer-preventive properties. These supplements are well-tolerated and widely available, and can form the backbone of a thoughtful, long-term, overall disease prevention strategy.
If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.
- Available at: http://www.cancer.org/acs/groups/content/documents/document/acspc-042280.pdf. Accessed May 2, 2016.
- Available at: http://www.ccalliance.org/get-information/what-is-colon-cancer/statistics/. Accessed May 2, 2016.
- Available at: http://www.cancer.gov/types/colorectal/patient/colorectal-prevention-pdq#section/all. Accessed May 2, 2016.
- Available at: http://www.cancer.org/cancer/colonandrectumcancer/detailedguide/colorectal-cancer-key-statistics. Accessed May 11, 2016.
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