Food is Medicine for Cancer Prevention

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 around the world, making it responsible for approximately 1 in every 6 deaths [1]. Among the millions of cases seen globally each year, approximately 400,000 of them are in children [1, 2]. This burden has driven researchers and health care professionals all over the world to dedicate their time, energy, and money to the development of treatments and therapeutic strategies, in an effort to combat cancer. While treatment is undeniably important, it is also very important to consider that between 30% and 50% of cancers are preventable [1]. Despite prevention offering the most cost-effective and long-term strategy for the control of cancer, it is an underserved area of both knowledge translation and research. 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 intake [1]. Therefore, a concerted effort to avoid cancer risk factors and implement evidence-based prevention strategies presents a plausible way to significantly lower an individual’s chance of ever developing cancer in the first place [1].

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 pollution [1]. 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 working outside with constant sun exposure, 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.

Notably, there is significant research already available on the anticancer properties of certain foods that provides substantive support for the application of nutrition as a cancer prevention strategy. In order to make proper nutrition widely recognized as a cancer prevention tool, it is important for this research to be extensively shared with the public and promoted – a goal that organizations like Anticancer.ca are currently working towards. Anticancer.ca is an independent organization committed to providing the public with easy-to-understand, evidence-based information to help inform cancer prevention and treatment strategies [3]. A key part of the information dissemination process is ensuring that complex data and scientific jargon is translated into lay person terms so that all populations can understand the data and put it to use in their everyday lives. Overall, a greater emphasis on nutrition in cancer prevention is a promising step forward in the fight against cancer but requires a careful look at the nutrition recommendations currently available.

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 World Health Organization (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 day [7]. Additionally, trans fats should be limited or replaced with unsaturated fats and omega-3s [7]. Overall, plant-based food consumption should be favoured when possible and water (8-12 cups per day) should be the drink of choice [7].

The Biological Foundations of Anticancer Nutrition

The general recommendations detailed above are considered cancer-preventative because of their protective biological effects within the human body. Fruits and vegetables contain an assortment of phytonutrients such as antioxidants, fiber, vitamins, and minerals that help the body carry out important physiological processes, many of which protect against cancer [7]. Phytonutrients, also called phytochemicals, are compounds produced by plants that often work with other essential nutrients to promote health [8]. For instance, research has shown that phytonutrients such as sulforaphane, epigallocatechin gallate, genistein, phenethyl isothiocyanate, curcumin, vitamin C, indole-3-carbinol, and lycopene possess anticancer effects [9]. Although these vary based on the nutrient, some effects include protecting cells from oxidative damage through antioxidant activity, enhancing one’s immunological response to malignant cells, inhibiting angiogenesis, and inhibiting cell proliferation by inducing cell cycle arrest [9].

A specific example is the phytonutrient sulforaphane, commonly found in cruciferous vegetables such as broccoli, brussels sprouts, cauliflower, and purple cabbage [10]. Consumption of these vegetables is often associated with a lower risk of developing cancer at various sites such as the prostate, breast, lung, and colon [10]. 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 damage [10]. 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 inflammation [7]. 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 prevention[7]. Chia seeds are good sources of copper, iron, manganese, selenium, calcium, and zinc which are essential for proper cellular function [7].

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 2042 [12]. Some of the risk factors studied included unhealthy eating habits, sedentary behaviour, UV radiation, air pollution, and excess weight [12]. In regards 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 2042 [12]. 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.

In conclusion, cancer is a growing public health concern that has the undivided attention of organizations such as the ACS, CCS, and WCRF. Even the United Nations, which focuses on a wide range of global issues, emphasizes cancer as one of the non-communicable diseases for which they aim to reduce premature mortality by 2030 [13]. With the whole world working aggressively to prevent and treat this horrible disease, it is important to not overlook the strategies currently available right at our fingertips. Leveraging what we already know about nutrition presents a simple and effective way to help reduce our cancer risk and improve global health.

For more information, please visit https://anticancer.ca/

Katerina Carrozzi (she/her) is a third -year undergraduate student at the University of Toronto majoring in Biology and minoring in Immunology and Physiology. She submitted this article as a guest writer for our magazine. Katerina is interested in researching the anticancer properties of various phytonutrients to determine how we can optimize nutrition to help prevent cancer.

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] Anticancer.ca. (2023). About Anticancer.ca. Retrieved January 6, 2024, from https://anticancer.ca/docs/about-anticancerca

[4] Canadian Cancer Society. (n.d.). Reduce your risk. Retrieved November 28, 2023, from https://cancer.ca/en/cancer-information/reduce-your-risk

[5] American Cancer Society. (n.d.). American Cancer Society guideline for diet and physical activity. Retrieved November 28, 2023, from https://www.cancer.org/cancer/risk-prevention/diet-physical-activity/acs-guidelines-nutrition-physical-activity-cancer-prevention/guidelines.html

[6] World Cancer Research Fund. (n.d.). Eat wholegrains, vegetables, fruit and beans. Retrieved November 28, 2023, from https://www.wcrf.org/diet-activity-and-cancer/cancer-prevention-recommendations/eat-wholegrains-vegetables-fruit-and-beans/

[7] Sunderji, A. (2023, June 15). General cancer prevention. Anticancer.ca. Retrieved November 28, 2023, from https://anticancer.ca/docs/general-cancer-prevention

[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

[9] Ranjan, A., Ramachandran, S., Gupta, N., Kaushik, I., Wright, S., Srivastava, S., Das, H., Srivastava, S., Prasad, S., & Srivastava, S. K. (2019). Role of phytochemicals in cancer prevention. International Journal of Molecular Sciences, 20(20), 4981. https://doi.org/10.3390/ijms20204981

[10] Carrozzi, K. (2023, June 8). Sulforaphane. Anticancer.Ca. Retrieved November 28, 2023, from https://anticancer.ca/docs/sulforaphane

[11] Barber, T. M., Kabisch, S., Pfeiffer, A. F. H., & Weickert, M. O. (2020). The health benefits of dietary fibre. Nutrients, 12(10), 3209. https://doi.org/10.3390/nu12103209

[12] ComPARe Study Team. (2019). Risk reduction. Canadian Cancer Society. Retrieved November 28, 2023, from https://data.prevent.cancer.ca/future/risk-reduction

[13] United Nations Department of Economic and Social Affairs. (n.d.). Ensure healthy lives and promote wellbeing for all at all ages. United Nations. Retrieved November 28, 2023, from https://sdgs.un.org/goals/goal3#targets_and_indicators