The Anti-Cancer Diet

Here is a paper I wrote for my oncology class. Cancer is so prevalent these days. Its highly likely that you or someone you know has been diagnosed with cancer. Or maybe you want to do everything you can to prevent cancer. Diet plays a significant role in both the prevention of cancer and the treatment of cancer. Here ya go.

Cancer is a disease that is commonly believed to be preventable. All cancers are a result of multiple mutations. These mutations are due to interaction with the environment. Genes, on the other hand, have very little impact on the development of chronic disease and life outcomes. Only 5-10% of all cancers can be attributed to genetic defects. The remaining 90-95% of cancer cases are caused by environmental and lifestyle factors. As Craig Venter, pioneer genomic researcher stated, “Most biology will come from the complex interaction of all the proteins and cells working with environmental factors, not driven directly by genetic code.”¹

These environmental and lifestyle factors include cigarette smoking, diet, alcohol,

environmental toxins and pollutants, sun exposure, infections, stress, physical inactivity, and obesity. According to a study published in the Journal of National Cancer Institute, 30-35% of all cancer deaths in the US are linked to diet.² This is exemplified by the variation of cancer incidence in different countries and by the changes of cancer rates upon migration. For instance, Asians have a 25 times lower incidence of prostate cancer and a ten times lower incidence of breast cancer as compared to their Western counterparts. However, the rates for these cancers increase significantly after Asians migrate to Western countries.¹

This paper highlights the role of diet in the prevention and treatment of cancer. There are additional modifiable risk factors, such as smoking, alcohol consumption, obesity, stress, and physical inactivity that should not be overlooked in the prevention and treatment of cancer. Diet, however, makes up the greatest impact of all these lifestyle factors in the prevention of cancer deaths. Therefore, it should be a primary focus in the integrative cancer treatment plan.

Reducing Carcinogens in the Diet

Carcinogens are defined as agents known to directly cause cancer. Most ingested carcinogens come from food itself, food additives or from the cooking process. Colorectal cancer has a high correlation with ingestion of carcinogens, such as nitrates, nitrosamines, pesticides, and dioxins. Diet is linked to cancer deaths in 70% of colorectal cancer cases.¹

Red meat consumption is a risk factor for not only gastrointestinal cancers but also for prostate, bladder, breast, and pancreatic cancers. This is likely due to the process involved in cooking red meat. Cooking meat at high temperatures, such as grilling with charcoal and smoking, creates cancer-producing carbon compounds such as pyrolysates and amino acids.¹ Meat and the heterocyclic amines formed in cooking have been linked to breast, colon and rectal cancer^.3

Frequent consumption of nitrates and nitrites also increases the risk of various cancers. They are commonly used as preservatives of processed meat.

A practical recommendation for patients wishing to prevent cancer and for patients diagnosed with cancer is to minimize their meat consumption, especially red meat, and to subsequently increase their fruit and vegetable intake. One to two servings of red meat per week are advised.

Increasing Consumption of Antioxidants

Despite numerous scholarly articles and reviews published on the role of antioxidants and cancer prevention and treatment, their benefits have been ignored. Many clinical oncologists believe that antioxidants may negate the free radical producing effect of chemotherapeutic agents and therefore discourage their use. However, this concern is invalidated by several in vitro and in vivo studies underscoring the benefits of antioxidants in cancer care.⁴

Antioxidants, which include vitamin A, vitamin E, vitamin C, and carotenoids, have many beneficial roles in the prevention and treatment of cancer. First, supplemental antioxidants potentiate the efficacy of chemotherapy. The proposed mechanism is by reducing chemotherapy induced toxicity on normal cells and by enhancing their growth inhibitory effects on cancer cells.⁴

Antioxidants have been studied in cell culture models, transplanted tumors in syngeneic animals and in athymic mice, and in patients with certain tumors. These studies revealed that supplemental antioxidants have been shown to induce differentiation in cancer cells. In addition, they regulate gene expression in cancer cells.⁴ Supplemental antioxidants to consider in cancer treatment include vitamin A, vitamin E, vitamin C, green tea extract, grape seed extract and alpha lipoic acid.

While supplemental antioxidants are recommended as an integrated cancer therapy, dietary intake of antioxidants should not be overlooked. Studies show, for example, that an overall intake of carotenoids is more protective than a high intake of a single carotenoid.³ Sources of carotenoids include carrots, pumpkins, and winter squash.

Another antioxidant that has received a lot of attention in the prevention of cancer is lycopene, a substance found in tomatoes, primarily in cooked tomatoes. Lycopene has been found to be very protective, especially in prostate cancer. The Health Professionals Follow-Up Study revealed the association between the combined intake of tomatoes, tomato sauce, tomato juice, and pizza and a 35% lower risk of prostate cancer. Interestingly, lycopene was associated with a 53% decrease in risk in advanced stages of prostate cancer, proving to be even more effective in later stages.⁴

An anti-cancer diet should consist of a diet rich in colorful fruits and vegetables translating to a high intake of antioxidants. In a review of the relationship between fruits, vegetables, and cancer in 206 human epidemiological studies and 22 animal studies, there was substantial evidence for a protective effect of greater vegetable and fruit consumption for many cancers.³

Increasing Cruciferous Vegetables in the Diet

Cruciferous vegetable consumption has been implicated in the prevention of many different cancers, including lymphoma, breast, prostate, bladder, and lung cancer. Cruciferous vegetables contain the anti-cancer substances, sulforophane and indole-3-carbinol.³ Sources of cruciferous vegetables include broccoli, broccoli sprouts, cabbage, cauliflower, brussel sprouts and kale.

A study in China found an inverse relationship between cruciferous vegetable intake and breast cancer risk. In addition, the Nurses’ Health Study revealed the association between a high intake of cruciferous vegetables (defined as five or more servings per week) and a 33% reduction of non-Hodgkin’s lymphoma.³

Sulforphane is involved in induction of phase 2 enzymes to detoxify carcinogens.¹ The highest source of sulforophane is found in broccoli sprouts. One sprout contains the same amount of sulforophane as an entire full-grown broccoli plant.

The flavonoid indole-3-carbinol found in cruciferous vegetables modulates several nuclear transcription factors. Indole-3-carbinol also induces phase 1 and phase 2 enzymes in the liver that metabolize estrogens and other carcinogens. This provides rationale that a high consumption of cruciferous vegetables should be included in cases of breast cancer.¹

An anti-cancer diet should include cruciferous vegetables (especially broccoli sprouts) due to their powerful anti-cancer effects. A daily intake of 2 servings is recommended.

Increasing Fiber Intake

Fiber is found in whole grains, seeds, legumes, fruits and vegetables. Refined grains, such as white bread, white rice, and processed foods have had the fiber removed from them. Dairy, eggs, and meat contain no fiber. A diet rich in animal products and refined grains are devoid of fiber and increase the risk of many cancers.³

Flax seeds are a good source of both soluble and insoluble fiber. Not only are they high in fiber, but flax seeds are also rich in the dietary phytoestrogens, lignans and isoflavonoids. These compounds influence sex hormone metabolism, intracellular enzymes, protein synthesis, growth factor action, malignant cell proliferation, and angiogenesis.⁵ They should therefore be consumed daily (2-4tbsps) in the form of ground flax.

It has been found that insoluble fiber, found in whole grains, can reduce the risk of bowel cancer. Insoluble fiber ferments in the gut, producing short-chain fatty acids such as butyrate. Butyrate is a suppressor of tumor formation.¹

In addition to the tumor suppression function of fiber, it also prevents blood sugar from spiking, translating to a favorable glucose response.

Promoting a Favorable Glucose Response

Sugar and refined grains are high in glucose and cause a subsequent spike in insulin levels. This can lead to not only diabetes but also cancer. The Nurses’ Health Study found an association between elevated fasting glucose, fasting insulin, elevated glucose 2 hr postprandial, and a larger waist circumference with a higher risk of colorectal cancer.³

Whole grains, such as whole wheat bread, quinoa, oats, and brown rice, do not cause a rapid spike in blood sugar and insulin levels as opposed to refined grains. Whole grains have been shown to be protective against breast cancer.

Dysregulated blood sugar is associated with an increased risk of many different cancers. Avoidance of refined grains and sweets should be an integral part of the anti-cancer diet.

Summary- Foods to Include as Part of the Anti-Cancer Diet

• Colorful vegetables everyday- broccoli, broccoli sprouts, kale, brussel sprouts, carrots, winter squash, spinach, beets, purple cabbage, tomatoes (2 cups dark leafy greens and 1 cup of cruciferous vegetables)
• Deeply pigmented fruit daily- blueberries, raspberries, red grapes, pomegranate (1 cup)
• 2-4 tablespoons of ground flax seed per day- sprinkle on yogurt, oatmeal, smoothies, salads
• Whole grains- oats, whole wheat, barley, quinoa, millet, brown rice, wild rice
• Legumes- lentils, black beans, garbanzo beans, red kidney beans
• Healthy fats- salmon, olive oil, walnuts, fish oil, almonds, coconut
• Eat organic when possible
• A Mediterranean diet is consistent with all of these recommendations. A lower incidence of breast cancer in Mediterranean populations has been attributed to a Mediterranean diet. It is estimated that 15 % of the incidence of breast cancer could be prevented if the populations of highly developed western countries shifted to a traditional Mediterranean diet.⁶

Summary- Foods to Avoid or Minimize

• Red meat, especially when grilled or smoked
• Grain-fed meat and dairy (buy organic when possible)
• Trans fat
• Sugar
• Refined grains- white bread, white rice, pasta

There is substantial evidence that nutrition plays a major role in the cancer process. In a world where 10 million people worldwide are expected to be diagnosed with cancer this year, it is wise for everyone to follow these guidelines.¹ These guidelines can be used to prevent primary cancer and the reoccurrence of cancer. This diet can also be part of cancer treatment to aid in recovery.

References

1. Anand, Preetha, Kunnumakara, Ajaikumar, et al. (2008). Cancer is a preventable

disease that requires major lifestyle changes. Pharmaceutical Research, September 2008; 25(9): 2097-2116.

2. R. Doll, and R. Petro. (1981). The causes of cancer: quantitative estimates of

avoidable risks of cancer in the United States today. Journal of National Cancer

Institute. 66:1191-308.

3. Donaldson, Michael S. (2004). Nutrition and Cancer: A review of the evidence for an

anti-cancer diet. Nutrition Journal, October 2004; 10: 1186-1195.

4. Prasad, Kedar, Kumar, Arun, et al. (1999). High Doses of Multiple Antioxidants

Vitamins: Essential Ingredients in Improving the Efficacy of Standard Cancer

Therapy. Jounral of the American College of Nutrition, 18(1):13-25.

5. Adlercreutz, Herman. (1995). Phytoestrogens: Epidemiology and a Possible Role in

Cancer Protection, Environmental Health Perspective, 103(7):103-112.

6. Tseng, Marilyn, Sellars, Thomas, et al. (2008). Mediterranean diet and breast density

in the Minnesota Breast Cancer Family Study, Nutr Cancer, 60(6): 703-709.