Can a Healthy Diet Prevent Cancer?
People often ask if there are foods that may help to prevent cancer, and foods that may cause cancer. The current cancer prevention guidelines suggest that instead of focusing on specific single nutrients or foods, people should use a holistic approach to food to reach healthy results. It is important to understand that eating healthy food is not a guarantee of avoiding cancer, but it can help to reduce the risk of cancer.
Common questions include: Does eating meat increase the risk of cancer? Are fruits and vegetables good for cancer prevention? How about milk, cheese, and coffee? What if we switch between fasting and eating on a regular basis? Over the years, scientists have been working to understand the potential cancer-prevention benefits of common food items, as well as intermittent fasting.
It has been suggested that red meat and processed meats increase the risk of cancer, and some health organizations recommend limiting or avoiding consumption of these foods.1 Red meat refers to unprocessed meat such as beef, pork, and lamb; processed meats refers to bacon, sausage, ham, and hot dogs, which have been changed through some processes to improve preservation or enhance flavor.
It has also been shown that whole grains, vegetables, and fruits have cancer-prevention benefits. For instance, a report by the World Cancer Research Fund and the American Institute for Cancer Research says that there’s “strong evidence” that eating non-starchy vegetables and fruit helps to protect people against cancers of respiratory and upper digestive tracts, including mouth, throat, esophagus, lung, and stomach cancers.2
Dairy products, such as milk, yogurt, and cheese, contribute various nutrients to our diet and are recommended in most dietary guidelines, but no clear association has been found between dairy intake and cancer.3 By contrast, recent evidence shows that moderate consumption of coffee, particularly caffeinated coffee (between 1 to 6.5 cups a day), is associated with a lower rate of death from cancer.4
How may coffee decrease the risk of death from cancer? Coffee contains antioxidant components such as caffeine and other polyphenol compounds, which may reduce inflammation, and in turn, reduce the risk of some cancers.4
Fasting has a rich history rooted in religious traditions and has been practiced for thousands of years. With intermittent fasting, people only eat during a specific time or eat just one meal a couple of days a week.
Despite the benefits of intermittent fasting in managing weight and preventing some diseases, its effects on cancer prevention or treatment are still unclear. Some preliminary research findings suggest that prolonged fasting in some patients with cancer is safe and can potentially decrease chemotherapy-related side effects and tumor growth.5 However, except for a clinical trial setting, researchers currently do not recommend intermittent fasting for patients who are receiving active cancer treatment.5
Healthy Dietary Patterns and Cancer
National cancer prevention guidelines have been shifting from a nutrient-centric approach to a more holistic approach of diet that is characterized as dietary patterns. The primary reason for this shift is that studying single nutrients or foods has not shown benefits in understanding the potential preventive effects of nutrition in cancer.
Dietary patterns are defined as the quantities, proportions, variety, or combination of different foods, drinks, and nutrients in diets, and the frequency with which they are regularly consumed.6 The American Cancer Society recommends a healthy eating pattern that includes7:
- A variety of vegetables, fruits, and whole grains
- Fruits, especially whole fruits in a variety of colors
- Whole grains
In addition, a healthy eating pattern reduces, or eliminates7:
- Red and processed meats
- Sugar-sweetened beverages
- Highly processed foods, and refined grain products
Some researchers categorized dietary patterns into “prudent” (fruits and vegetables), “Western” (red meat, sweets, pastries, oils), “traditional” (red meat, legumes, potatoes, bread), and “fish and alcohol,” and found that greater adherence to the “Western” and “traditional” diets increased the risk of cancer.8
By comparison, plant-based dietary patterns, such as the Mediterranean diet, may help to reduce the risk of death from cancer in the general population, and among cancer survivors, and may also help to prevent colorectal, head and neck, respiratory, gastric, liver, and bladder cancers.9
The Mediterranean diet is characterized by high amounts of fruits, vegetables, nuts, legumes, fish, cereals made from whole grains, and extra-virgin olive oil; it also calls for reducing the intake of red and processed meat, eggs, and dairy.9
How can the Mediterranean diet help to prevent cancer? The beneficial effects of the Mediterranean diet come from the high contents of antioxidants and anti-inflammatory nutrients contained in those foods, which can help to prevent and counteract DNA damage, and has been shown to slow the development of certain types of cancer.10
- Rock CL, Thomson C, Gansler T, et al. American Cancer Society guideline for diet and physical activity for cancer prevention. CA: A Cancer Journal for Clinicians. 2020;70(4):245-271.
- World Cancer Research Fund, American Institute for Cancer Research. Diet, nutrition, physical activity and cancer: a global perspective: the third expert report. Published 2018. www.wcrf.org/diet-and-cancer/. Accessed February 3, 2022.
- Lu Y, Sugawara Y, Matsuyama S, et al. Association of dairy intake with all‑cause, cancer, and cardiovascular disease mortality in Japanese adults: a 25‑year population‑based cohort. European Journal of Nutrition. November 8, 2021. Online ahead of print.
- Torres-Collado L, Compañ-Gabucio LM, González-Palacios S, et al. Coffee consumption and all-cause, cardiovascular, and cancer mortality in an adult Mediterranean population. Nutrients. 2021;13(4):1241.
- Clifton KK, Ma CX, Fontana L, Peterson LL. Intermittent fasting in the prevention and treatment of cancer. CA: A Cancer Journal for Clinicians. 2021;71(6):527-546.
- 2020 Dietary Guidelines Advisory Committee. Scientific Report of the 2020 Dietary Guidelines Advisory Committee. www.dietaryguidelines.gov/sites/default/files/2020-07/PartD_Ch8_DietaryPatterns_first-print.pdf. Accessed February 3, 2022.
- American Cancer Society Guideline for Diet and Physical Activity. www.cancer.org/healthy/eat-healthy-get-active/acs-guidelines-nutrition-physical-activity-cancer-prevention/guidelines.html. Accessed February 3, 2022.
- Entwistle MR, Schweizer D, Cisneros R. Dietary patterns related to total mortality and cancer mortality in the United States. Cancer Causes & Control: CCC. 2021;32(11):1279-1288.
- Morze J, Danielewicz A, Przybyłowicz K, et al. An updated systematic review and meta‑analysis on adherence to Mediterranean diet and risk of cancer. European Journal of Nutrition. 2021;60(3):1561-1586.
- Mentella MC, Scaldaferri F, Ricci C, et al. Cancer and Mediterranean diet: a review. Nutrients. 2019;11(9):2059.