Food is Medicine for Cancer Prevention

Katerina Carrozzi

This article was originally published in Juxtaposition Global Health Magazine on January 29, 2024 (https://www.juxtamagazine.org/editorial/food-is-medicine-for-cancer-prevention).
This is an updated version published on July, 2024. 

Introduction

Cancer, a word needing no introduction. A leading cause of death worldwide. A major global health burden. 

Recent statistics show that cancer accounts for nearly 10 million deaths annually, therefore making it responsible for approximately 1 in 6 deaths worldwide¹. Among the millions of cases seen globally each year, approximately 400,000 of them are in children^1,2. The World Health Organization (WHO) predicts that cancer rates will steadily climb³. In 2022, 20 million cases were recorded and by 2050, we will see over 35 million cases per year – a 77% increase³. This growing burden has spurred worldwide efforts to combat cancer, from cancer treatment research to therapeutic drug development, billions of dollars have gone into discovering ways to manage and treat this disease. While treatment is undeniably important, it is crucial to recognize that between 30% and 50% of cancers are preventable¹. Despite prevention offering the most cost-effective and long-term strategy for the control of cancer, it remains an underserved area of research. Notably, around one-third of deaths from cancer are due to tobacco use, high body mass index, alcohol consumption, a lack of physical activity, and low fruit and vegetable intake¹. This underscores the potential impact of targeted prevention strategies and shows that a concerted effort to avoid cancer risk factors and implement evidence-based prevention methods may significantly reduce an individual’s chance of ever developing cancer in the first place¹. 

Nutrition as a cancer prevention strategy

Many well-known strategies for cancer prevention include avoiding tobacco use, maintaining a healthy body weight, eating a balanced diet rich in fruits and vegetables, engaging in regular physical activity, avoiding or reducing alcohol consumption, getting vaccinated against HPV and Hepatitis B, and minimizing exposure to UV radiation and air pollution¹. Different versions of this extensive list are often published across a variety of cancer-related platforms for the public to consult in their everyday lives. Despite the numerous strategies, practicality remains an issue. For example, minimizing UV exposure may be difficult for individuals who work outside in the sun, and effectively reducing exposure to air pollution may be impossible for those who live in polluted areas. Among these cancer prevention strategies, however, nutrition stands out as a relatively simple and cost-effective avenue worth exploring. While the cost of "eating healthy" might be higher in some areas, it is generally more cost-effective than getting sick! 

General cancer preventative nutrition recommendations

 A spotlight on anticancer nutrition quickly reveals the abundance of information on the topic, so much so that it is often overwhelming. Although it can be challenging to determine which foods are best to consume based on the numerous scientific articles and recommendations available, some general trends can be found across sources. 

Leading organizations such as the American Cancer Society (ACS), the Canadian Cancer Society (CCS), and the WHO broadly recommend that individuals should make wholegrains, vegetables, fruit, and legumes a major part of their usual diet^1,4,5.  More specifically, the World Cancer Research Fund (WCRF) and Anticancer.ca state that individuals should consume a diet that provides 1.5-3 cups of grains (half wholegrains), 30 g of fibre, 2.5 cups of fruit, and 3 cups of vegetables each day^6,7. In terms of specific foods, these organizations recommend legumes such as beans and lentils, non-starchy vegetables, whole fruits of different colours, non-starchy roots and tubers such as carrots, artichokes and celery root, and wholegrains such as brown rice, wheats, oats, barely and rye^6,7. 

Furthermore, individuals are advised to limit or exclude processed meats, sugar-sweetened beverages, highly processed foods, refined grain products, and alcohol^1,4-6. More specifically, research suggests limiting red meats to 12-18 ounces per week (opting for poultry, fish and plant-based alternatives instead), sugar to 100 calories out of every 2000 calories consumed, and salt to 5-6 grams per day⁷. Additionally, trans fats should be limited or replaced with unsaturated fats and omega-3s⁷. Overall, plant-based food consumption should be favoured when possible and water (8-12 cups per day) should be the drink of choice⁷. 

The biological foundations of anticancer nutrition 

The cancer-preventative nature of these dietary recommendations stems from the protective biological effects of certain compounds found in these foods. Fruits and vegetables are rich in phytonutrients which are plant-produced compounds that work alongside essential nutrients to promote health⁸. These include antioxidants, fiber, vitamins, and minerals, which support crucial physiological processes that help protect against cancer⁷.

Research has identified several phytonutrients with anticancer properties, including sulforaphane, epigallocatechin gallate, genistein, curcumin, vitamin C, indole-3-carbinol, and lycopene⁹. While their specific effects vary, these compounds generally: protect cells from oxidative damage through antioxidant activity, enhance the immune system's response to malignant cells, inhibit the formation of new blood vessels that feed tumors (angiogenesis), and slow or stop cell division by inducing cell cycle arrest⁹. 

 A specific example is the phytonutrient sulforaphane, commonly found in cruciferous vegetables such as broccoli, Brussels sprouts, cauliflower, and purple cabbage¹⁰.

Consumption of these vegetables is often associated with a lower risk of developing cancer at various sites such as the prostate, breast, lung, and colon¹⁰. This is because sulforaphane inhibits cell proliferation by downregulating genes related to cell cycle progression and promotes detoxification by activating a signalling pathway that helps protect cells from DNA damage¹⁰. This is just one out of the many plant-based substances that support a cancer-preventative lifestyle. 

The other beneficial effects of general diet recommendations pertain to fibre, whole grains, and seeds. Fibre helps slow digestion and reduces the feeling of hunger, resulting in less weight gain and thereby decreasing the risk of cancer, diabetes, and cardiovascular disease^7,11.

 Additionally, whole foods such as wholegrains are important to eat as they generally retain more nutrients than processed foods and can also help reduce inflammation⁷. Lastly, seeds, such as hemp seeds and flaxseeds, are a good source of plant-based omega-3 fatty acids, fibre and lignans, all of which are important for cancer prevention⁷. Chia seeds are good sources of copper, iron, manganese, selenium, calcium, and zinc which are essential for proper cellular function⁷.

A look into the future 

Even after seeing recommendations about how a proper diet may potentially reduce cancer risk, some individuals may still question the overall effectiveness of such strategies. An interesting study conducted by the Canadian Cancer Society called “ComPARe” (Canadian Population Attributable Risk of Cancer) estimated the impact of reducing exposure to certain cancer risk factors on the total number of all associated cancer cases in Canada by the year 2042¹². Some of the risk factors studied included unhealthy eating habits, sedentary behaviour, UV radiation, air pollution, and excess weight¹². In regard to nutrition, this study made four estimations that provided particularly compelling insight: 1) if everyone increased their fruit intake by 2 servings per day, this could prevent 116,118 cancer cases by 2042; 2) if everyone increased their vegetable intake by 2 servings per day, this could prevent 79,809 cancer cases by 2042; 3) if everyone reduced processed meat consumption by 1 serving per week, this could prevent 24,792 cancer cases by 2042; and 4) if everyone reduced their red meat intake by 2 servings per week, this could prevent 25,818 cancer cases by 2042¹². For some people, this insight into the future may make short-term lifestyle changes more appealing and provide a tangible argument for why they should adopt certain nutrition prevention strategies. 

Conclusion

With the whole world working aggressively to prevent and treat cancer, it is crucial not to overlook the simple and effective strategies right at our fingertips. In conclusion, leveraging our knowledge about nutrition presents a practical way to help reduce cancer risk and improve global health.

About the author

References

1. World Health Organization. (n.d.). Cancer. Retrieved November 28, 2023, from https://www.who.int/news-room/fact-sheets/detail/cancer
2. World Cancer Research Fund International. (n.d.). Worldwide cancer data. Retrieved November 28, 2023, from https://www.wcrf.org/cancer-trends/worldwide-cancer-data/
3. World Health Organization. (2024, February 1). Global cancer burden growing, amidst mounting need for services. Retrieved June 23, 2024, from https://www.who.int/news/item/01-02-2024-global-cancer-burden-growing--amidst-mounting-need-for-services
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8. US Department of Agriculture. (n.d.). Phytonutrients. USDA National Agricultural Library. Retrieved November 28, 2023, from https://www.nal.usda.gov/human-nutrition-and-food-safety/food-composition/phytonutrients
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10. Carrozzi, K. (2023, June 8). Sulforaphane. Anticancer.Ca. Retrieved November 28, 2023, from https://anticancer.ca/docs/sulforaphane
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12. ComPARe Study Team. (2019). Risk reduction. Canadian Cancer Society. Retrieved November 28, 2023, from https://data.prevent.cancer.ca/future/risk-reduction