Good question! I have to be honest and say that there isn’t one cancer fighting diet. However, there are a variety of eating habits that have been shown in the research over and over again to reduce risk of cancer. If you already have cancer, you may be asking yourself why you need to reduce your risk. Well, reducing risk refers to risk of new cancer diagnosis, progression, and recurrence. So basically this pattern of eating is healthy for anyone. And the best part…it’s flexible so you can adjust and modify to suit your individual needs.
Does nutrition really make a difference in cancer risk?
Cancer is a complex set of diseases. We frequently don’t know what factors contributed to someone’s cancer diagnosis. The most recent research suggests that lifestyle factors contribute to 18% of new cancer diagnosis and 15% of cancer deaths. (1) I frequently hear my patients say that they lived a very healthy lifestyle, never smoked, rarely drank, ran marathons, and still got cancer. You know what…cancer’s not fair! Does that mean that you should just give up and eat cake for breakfast (well, not saying you can never have cake for breakfast!) and wash it down with glass of wine? No, how you choose to live your life even after a cancer diagnosis can impact your overall health and well-being.
What is a plant-based diet
This term is used a lot and is kind of confusing. A plant-based diet is NOT a vegan diet. It is also not a vegetarian diet. Some people are also using the term “plant-forward” diet. I have no idea what that term even means as there is no standard definition. In the context of cancer, a plant-based diet refers to 2/3 of your plate being plant based. What counts as a plant? Fruit, vegetables, grains, beans, lentils, nuts, and seeds. What doesn’t count as a plant? Beef, pork, chicken, turkey, eggs, cheese, yogurt, milk, cottage cheese, sausage, bacon, and other foods that come from an animal.
The recommendation to consume a plant-based diet is a shift from traditional nutrition advice. Historically we focused on specific nutrients or foods. Examples include limiting trans-fat or increase vitamin C intake. What we realized is that these recommendations are not consistent with how we eat! We don’t only eat or avoid one nutrient. Instead we eat whole foods. And just because you eat salmon once a week doesn’t cancel out the hot dogs and French Fries you have for dinner every other night of the week. So now we focus on eating patterns. In many ways this is liberating. It allows for flexibility and individuality. It puts you in the driver’s seat. The recommendations are just…well, recommendations. You get to decide what it looks like on your plate!
What is included in a healthy eating pattern?
As we discussed above, the focus is a plant-based eating pattern. This includes a variety of fruits, vegetables, whole grains, legumes, nuts, and seeds. Plant-based foods are very high in nutrients, high in fiber, high in antioxidants and help maintain healthy bacteria in the gut. They are also low in unhealthy saturated fats. In general, aim for 2.5-3 cups of vegetables per day and 1.5 to 2 cups of fruit each day. (2) Legumes (beans) are high in protein and fiber making them a great option for meatless meals.
Whole grain intake has been associated with decreased risk of colorectal cancer likely due to their phytochemical and dietary fiber intake. (3) Try to consume at least 1/2 of your grains as whole grains each day. While it can be challenging to identify what is a whole grain, a good rule of thumb is to choose grains that have at least 2-3 grams of fiber per serving. Whole grains include oatmeal, whole wheat bread, whole wheat pasta, brown rice, and quinoa.
What should I avoid or limit?
Red meat and processed meats have been associated with increased risk of colorectal cancer and possibly breast, esophageal, and prostate cancer. (4) Red meat includes beef, pork, and lamb while processed meat refers to any meat that has been smoked, cured, or processed to extend it’s shelf life. This includes bacon (sad face), hot dogs, bratwurst, sausage, pepperoni, lunch meat, deli meats, beef jerky, and salami.
Red meat tends to be higher in saturated fat and heme iron which may contribute to increased cancer risk. Try to limit red meat to 18 oz per week. Now let’s take a second to process that. 18 oz…that’s more than a pound of red meat per week! A hamburger is typically 4 oz so that would equate to 4 hamburgers per week! So before you freak out and never read a post from me again, take a good look at how much red meat you individually consume per week. Processed meats are a different story. Processed meats are high in nitrates and nitrites which may form cancer-causing agents when digested. And no, the organic deli meat you are buying is not lower in nitrates (more on that in a future post). (5) Processed meats should be limited to 2 oz per day which is the equivalent of 1 hot dog per day. I know, that’s a bummer. But it’s okay. You can do hard things!
Added sugars. There are 2 different types of sugar – naturally occurring sugar in fruits, vegetables, dairy, and whole grains and added processed sugar from white sugar, brown sugar, high-fructose corn syrup, brown rice syrup, and other random names that the food industry uses to confuse us. You should regularly consume foods with naturally occurring sugars. Research has shown over and over again that fruits, whole grains, and lower fat dairy are part of a healthy diet. You do not need to avoid these foods! Okay, cakes, candy, donuts, pie, cookies, brownies, ice cream…I can’t really say those are nourishing foods. So I refer to them as non-nutritive sweets. We don’t eat them to provide vitamins and minerals. We eat them because of family tradition, because ice cream can nourish the soul on a hot summer night, because camping isn’t camping without s’mores, because apple cider donuts are a required part of the pumpkin patch, and because sometimes we want to eat cake for breakfast. But, we should balance these non-nutritive sweets with other healthy foods. These non-nutritive sweets are very high in calories which can then limit the variety of nourishing foods you eat throughout the day. The important things to remember when it comes to sugar – eat non-nutritive sweets in moderation, balance those sweets with more nutritious foods, and include naturally occurring sugars found in fruits, dairy, and whole grains frequently.
Dairy is a complicated topic when it comes to cancer. In some cases, such as with colon cancer, dairy appears to be protective. Those who regularly consume about 2 cups of milk per day had lower rates of colon cancer when compared to those who had low milk intake. (6) However, in other cases like prostate cancer, dairy and higher calcium intakes have been associated with increased cancer risk. Because it is unclear if dairy consumption may contribute to cancer risk, I recommend including 0-3 servings of lower fat dairy daily. (6)
In Summary
Research has shown that focusing on fruits, vegetables, whole grains, beans, lentils, nuts, and seeds can help prevent risk of cancer diagnosis, progression, and recurrence. The best part about this eating plan is that it allows for individual flexibility. If have celiacs disease and need to avoid wheat, no problem! Choose gluten free breads and grains. Your partner has heart disease and needs to limit their intake of saturated fats, cholesterol, and sodium, we’ve got this! Fruits, vegetables, whole grains, nuts, and seeds are all part of a heart healthy eating pattern. You don’t like eating broccoli, that’s okay! Try cauliflower, asparagus, or spinach. Bottom line is that you get to choose while including the guidelines below.
- Fill 2/3 of your plate with plant-based foods.
- Regularly add a variety of fruits and vegetables into your daily routine.
- Limit red meat (beef, pork, and lamb) to 18 oz. per week.
- Limit processed meat (bacon, sausage, deli meat) to as much as possible and no more than 2 oz. per day.
- Choose lower fat dairy up to 2-3 times per day.
- Enjoy beans and lentils regularly.
- Focus on whole grains instead of more refined grains that are low in fiber.
- Add fish to at least one meal weekly.
- Balance your intake of non-nutritive high sugar sweets with more nutritious foods.
- Islami F, Goding Sauer A, Miller KD, et al. Proportion and number of cancer cases and deaths attributable to potentially modifiable risk factors in the United States. CA Cancer J Clin. 2018; 68:31-54.
- Rock C, Thomson C, Gansler T, et al. American Cancer Society Guideline for Diet and Physical Activity for Cancer Prevention. CA Cancer J Clin. 2020;0:1-27.
- Schwingshackl L, Schwedhelm C, Hoffmann G, et al. Food groups and risk of colorectal cancer. Int J Cancer. 2018;142:1748-1758.
- Han MA, Zeraatkar D, Guyatt GH, et al. Reduction of red and processed meat intake and cancer mortality and incidence; a systematic review and meta-analysis of cohort studies. Ann Intern Med. Published online October 1, 2019. doi:10.7326/M19-0699.
- wcrf.org/dietandcancer
- Chapelle N, Martel M, Toes-Zoutendijk E, et al. Recent advances in clinical practice: colorectal cancer chemoprevention in the average-risk population. Gut. 2020;0:1-12. doi:10.1136/gutjnl-2020-320990.