Diet and Cancer

There is ample evidence that food and lifestyle factors play a significant role in cancer risk, yet many doctors and oncologists do not address these factors with their patients.  And worse, some oncologists will go so far as to say, “diet has nothing to do with your cancer treatment.” For those who ask, “Should I change my diet to prevent cancer? or, “Should I change my diet to improve cancer treatment?” Let’s look at the evidence.  Click to Tweet

What does the research say about food habits and cancer risk?

One of the most thorough reports showing the links between diet, lifestyle and cancer was first published in 1997, and updated again in 2007 and 2018, with the latest research.   “Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective” is combined effort of the American Institute for Cancer Research and the World Cancer Research Fund International [1].  The team examined the results of more than 7,000 research studies, which were reviewed by 21 leading scientists to ensure that valid, well designed studies were used to create the summary report.

Several food groups highlighted in the report as decreasing cancer risk:

  • Fruits and non-starchy vegetables
  • Dietary fiber (non-starchy vegetables, beans, lentils, whole grains)
  • Whole grains (colorectal cancer in particular)
  • Coffee (liver and endometrial cancer in particular)

Several of the specific food groups highlighted in the report for increasing cancer risk:

  • Red meat, especially grilled or charbroiled meat
  • Processed meat (salted, cured, smoked meat like ham, bacon, brats, hot dogs)
  • High glycemic diet (sugar, refined carbs in bread, pasta, pastry etc) especially in its connection to obesity, which is strong risk factor for cancer
  • Alcohol (any quantity increases breast cancer risk, while higher quantity raises risk of colorectal and liver cancer)

The report’s conclusion, quoted in part here, reminds us that it’s a pattern of making daily choices for nutrient-dense foods and exercise, that reduces the inflammation and cellular damage that promote cancer:

“different patterns of diet and physical activity combine to create a metabolic state that is more, or less, conducive to the acquisition of the genetic and epigenetic alterations that lead to the phenotypical structural and functional alterations in cells described by the Hallmarks of Cancer” [1]

Echoing the conclusion of the AICR WCRF report, the NIH National Cancer Institute confirms that chronic inflammation increases the risk of cancer, by damaging DNA [2].  While a variety of factors contribute to chronic inflammation, the food choices we make each day are one such factor that we can control.  

The Mediterranean diet is an eating pattern that is well researched for its effect in lowering inflammation.  The Mediterranean diet is more plant-based, and relies less on dairy and animal protein as compared to the standard American diet.   It emphasizes…

  • Fruit
  • Vegetables
  • Legumes
  • Nuts, seeds
  • Whole grains
  • Extra-virgin olive oil, olives
  • Herbs, spices
  • Fish, seafood

The Mediterranean diet is well known to reduce the risk of cardiovascular disease, but many people don’t realize its anti-inflammatory foods also reduce cancer risk.  In a large study of diet and disease in the U.S. population, tracking more than 380,000 people for 5 years, those who ate a Mediterranean diet had less death caused by cancer [3].  

The most common cancers are breast, lung, prostate, and colon.  And, yes, other studies of the Mediterranean diet show a positive effect in specific cancers, [see sources below 4,5,6,7,8,9,10]:

  • Colorectal
  • Breast
  • Liver
  • Stomach
  • Prostate
  • Esophageal

Breast cancer is the most common type of cancer in women and it is estimated that 1 in 8 women in the United States will receive that diagnosis.  The CDC reports that the annual number of new cases of breast cancer continues to grow [11]. Here are a few of the many studies which highlight the connection of diet and lifestyle to breast cancer risk:

In a large study of breast cancer and the Mediterranean diet, women who consumed 1 liter of olive oil per week had 68% lower relative risk compared to the control group who ate a standard low-fat diet.  The study followed more than 4,000 women for 5 years [7].

Another study followed 1,500 women for 2 years after breast cancer diagnosis while tracking fruit and vegetable intake, along with physical activity.  The researchers found a “significant survival advantage” when physical activity (30 min/day) was combined with 5 or more servings of fruit and vegetables per day [12].  This effect occurred in women regardless of body size.

Take Action on the Factors that You Control

While we cannot control all of the risk factors for cancer, we can choose diet and lifestyle habits that reduce inflammation, and thereby decrease the likelihood of DNA damage and cellular dysregulation.  Research indicates that a diet abundant in fruits and vegetables, with healthy fats (like olive oil, avocado, nuts) and a lower intake of animal protein, along with regular physical activity, does reduce cancer risk.  

Resources to support Cancer Treatment:

        

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Sources:

[1] The Third Expert Report:Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective,” American Institute for Cancer Research and World Cancer Research Fund International, accessed July 23, 2018, https://www.wcrf.org/dietandcancer/contents

[2] “Risk Factors: Chronic Inflammation”.  National Cancer Institute, accessed July 23, 2018, https://www.cancer.gov/about-cancer/causes-prevention/risk/chronic-inflammation

[3] Mediterranean dietary pattern and prediction of all-cause mortality in a US population: results from the NIH-AARP Diet and Health Study. PN Mitrou et al. Arch Intern Med. 2007 Dec 10;167(22):2461-8.  DOI:10.1001/archinte.167.22.2461

[4] Italian Mediterranean Index and risk of colorectal cancer in the Italian section of the EPIC cohort. C Agnoli et al. Int J Cancer. 2013 Mar 15;132(6):1404-11. doi: 10.1002/ijc.27740. Epub 2012 Aug 7.

[5] Mediterranean diet and colorectal cancer risk: results from a European cohort. C Bamia et al. Eur J Epidemiol. 2013 Apr;28(4):317-28. doi: 10.1007/s10654-013-9795-x. Epub 2013 Apr 12.

[6] Spanish Mediterranean diet and other dietary patterns and breast cancer risk: case-control EpiGEICAM study. A Castello et al. Br J Cancer. 2014 Sep 23;111(7):1454-62. doi: 10.1038/bjc.2014.434. Epub 2014 Aug 7.

[7] Mediterranean Diet and Invasive Breast Cancer Risk Among Women at High Cardiovascular Risk in the PREDIMED Trial: A Randomized Clinical Trial. E Toledo et al. JAMA Intern Med. 2015 Nov;175(11):1752-60. doi: 10.1001/jamainternmed.2015.4838.

[8] Adherence to Mediterranean diet and risk of cancer: a systematic review and meta-analysis of observational studies. L Schwingshakl, G Hoffman. Int J Cancer. 2014 Oct 15;135(8):1884-97. doi: 10.1002/ijc.28824. Epub 2014 Mar 11.

[9] Mediterranean diet and prostate cancer risk and mortality in the Health Professionals Follow-up Study. SA Kenfield et al. Eur Urol. 2014 May;65(5):887-94. doi: 10.1016/j.eururo.2013.08.009. Epub 2013 Aug 13.

[10] Influence of the Mediterranean diet on the risk of cancers of the upper aerodigestive tract. C Bosetti et al. Cancer Epidemiol Biomarkers Prev. 2003 Oct;12(10):1091-4.

[11] U.S. Cancer Statistics Working Group. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention and National Cancer Institute; www.cdc.gov/cancer/dataviz, June 2018.

[12] Greater Survival After Breast Cancer in Physically Active Women With High Vegetable-Fruit Intake Regardless of Obesity. John Pierce et al.  J Clin Oncology, 2007, 25(17):2345-2351.  

[13] High- and low-fat dairy intake, recurrence, and mortality after breast cancer diagnosis.  CH Kroenke et al. J Natl Cancer Inst. 2013 May 1;105(9):616-23. doi: 10.1093/jnci/djt027. Epub 2013 Mar 14.

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