This is a challenging question because being vegetarian or vegan doesn’t necessarily mean eating “healthier.” What we know so far is that more plant-based foods do help reduce the risk of getting cancer, but being fully vegetarian or vegan doesn’t seem to improve the prognosis after a cancer diagnosis. Let’s get more in-depth.  

What "Vegetarian” and “Vegan” Mean

Vegetarian means different things to different people. For some, it involves not eating red meat, poultry, fish, and seafood. For others, it’s avoiding red meat and poultry but still eating fish (called “pescatarian”), dairy (called “lacto-vegetarian”), and eggs (known as “ovo-vegetarian”).  

Vegan means avoiding all foods that come from animals including eggs, dairy products (milk, cheese, sour cream, butter, ice cream), and honey.   

Research about Vegetarian and Vegan Eating Patterns When It Comes to Cancer

Large studies that follow people over time have found lower rates of cancer overall with less intake of red and processed meats. The problem, however, is that these studies can’t control for other things that might affect cancer risk. A good example is a study conducted in the UK of 472,377 people, whose self-reported eating patterns were categorized as follows:   

• Regular meat-eaters reported eating processed, red meat (beef, pork, lamb), or poultry five or more times/week.  

• Low meat-eaters reported eating processed, red meat (beef, pork, lamb), or poultry fewer than five times a week. 

• Fish-eaters reported never eating processed, red meat, or poultry and ate oily and/or non-oily fish. 

• Vegetarians reported never consuming any meat or fish. This group also included vegans who reported not consuming any dairy or eggs in addition to meat or fish.  

No one had cancer at the beginning of the study, and they were followed for more than eleven years. During that time, 11.6% of participants were diagnosed with cancer. The most significant finding was that low meat-eaters had less chance of developing colorectal cancer than regular meat-eaters. This study also found that low meat-eaters, fish-eaters, or vegetarians had a lower risk of all cancers, but that wasn’t entirely explained by eating less red meat. For example, vegetarian women had lower rates of postmenopausal breast cancer in this study, but that group of women also had a lower BMI, which the research showed was an equally likely reason for their lower risk as being vegetarian.  

Being Vegetarian or Vegan After a Cancer Diagnosis 

The analyses so far show being vegetarian or vegan does not improve cancer survivorship. This doesn’t mean plant-based eating patterns have no impact on cancer prognosis, but highlights the fact that more research is needed to understand many things, such as:

• Does the length of time being vegetarian or vegan matter?

• How do genetics factor into associations with vegetarianism/veganism?  

Things You May Be Wondering

• Is it okay to eat a small amount of red meat a few times a month? 

• Are processed meats like salami, bacon, and hot dogs riskier than other types of meat? 

Bottom Line 

As mentioned, the strongest evidence links processed meats (like hot dogs, sausage, bacon, and ham) to worse cancer-related outcomes. Eating red meat and processed meats often is also a risk factor for developing cancer.  

This means, that if you eat red meat, it’s best to keep your portion to a deck-of-cards size or less and limit the frequency of red meat intake to three times a week or less.   

It’s also worth thinking about processed meats like bacon, salami, hot dogs, and sausages as a separate category and one to minimize as much as possible in your eating pattern. 

Action Steps to Take to Eat Less Meat  

Use meat as a flavoring rather than the main dish. For example, choose small amounts of sliced, shaved, cubed, or ground meat as way to add flavor to veggie-loaded dishes like stir-fries, casseroles, burritos, soups, stews, and any mixed dishes.  

For recipes that have meat as an ingredient, try cutting the quantity of meat by 50% and adding a plant-based protein. For example, Turkish flatbreads with hummus and ground turkey/chickpeas in a 1:1 ratio.  

Designate one meal or day a week as meatless and explore vegetarian recipes with bold flavors.  

Cook kebabs (with skinless poultry) or lean meat and skewer lots of colorful vegetables with a few small pieces of meat. 

Check out a few of our Iris Care Team’s suggested recipes: 

• Mediterranean Flatbread 

• Veggie Skewers 

• Roasted Cauliflower and Lentil Tacos 

• Vegan Grilled Sweet Potato Black Bean Burrito Bowls