Can a Vegan or Vegetarian Diet Lower Colorectal Cancer Risk?
February 17, 2023
Can a Vegan or Vegetarian Diet Lower Colorectal Cancer Risk?
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Amit Desai, M.D., Gastroenterology

Colorectal cancer is the second-leading cause of cancer deaths in the United States and rounds out the Top Five when it comes to most commonly diagnosed cancers. Diet has long been linked with the risk of developing colorectal cancer, with the consumption of red meat and processed meats posing the largest risks. So, could a vegan or vegetarian diet actually help lower your risk?

We spoke with Amit Desai, M.D., a gastroenterologist at Texas Digestive Disease Consultants in Dallas, to get his insight on the matter.

What is Colorectal Cancer and What Influences Risk?

Colorectal cancer (CRC) is a type of cancer that affects your colon and rectum. Your colon and rectum make up your large intestine. CRC starts when abnormal and pre-cancerous growths in the inner lining of the intestine, known as polyps, start to get bigger, which in time can evolve into cancer.

“Although there is ongoing research, studies have suggested that diets high in processed and ultra-processed foods, whether vegan or non-vegan, can be linked to higher rates of colon cancer,” says Desai. “When we look specifically at meat consumption, diets higher in red meats (i.e., steak) and processed meats (i.e., sandwich meats) have also been linked to higher rates of colon cancer. However, there are many factors one should consider when we look at colon cancer risk. Dietary and lifestyle choices are some — but not all — of those factors.”

The Centers for Disease Control and Prevention (CDC) outlines the following risk factors for colorectal cancer:

  • inflammatory bowel disease
  • genetics and family history of colon cancer
  • low levels of physical activity or exercise
  • diets low in fiber and high in fat
  • diets high in processed meats
  • overweight and obesity
  • smoking of tobacco products
  • alcohol use

Can a Vegan or Vegetarian Diet Have a Positive Impact on Risk?

A vegetarian diet is traditionally a diet that focuses primarily on plants and plant products as the main source of food. This can include fruits, vegetables, beans, peas, grains, seeds and nuts.

A vegan diet is a more restrictive form of a vegetarian eating pattern, which excludes the consumption of all meat and animal products, including eggs, dairy, honey and seafood.

There are actually six main types of vegetarian diets including:

  • Lacto-vegetarian: This includes dairy products but excludes eggs and meat products.
  • Ovo-vegetarian: This doesn’t include meat and dairy products but does include eggs.
  • Lacto-ovo-vegetarian: This includes eggs and dairy products while restricting meat products.
  • Pesco-vegetarian: Also known as pescatarian, it includes fish intake but limits consumption of other meats like poultry or beef.
  • Flexitarian: Also known as semi-vegetarian, it includes both fish and other meats, but limits the consumption of these animal products to no more than once a week.
  • Vegan: This doesn’t allow for animal products, including animal-derived ones like honey.

According to results from a 7-year study involving more than 77,000 people, those who followed a vegetarian diet had a 22% lower risk of CRC compared to nonvegetarians. Additionally, results from a 20-year study, which followed more than 10,000 people, found a significant CRC risk reduction in vegetarians than in those who consumed meat regularly.

As for vegans, research shows a 16% lower risk of colorectal cancer compared to nonvegetarians. Additionally, vegan diets are known to be high in fiber, and it’s well-established that eating a high-fiber diet can help reduce the risk of colon cancer.

However, it’s important to note that you don’t have to commit to fully going vegan or vegetarian to reap the benefits of plant-based eating.

One of the biggest things that stand in the way of plant-based diets tends to be a misconception about what “plant-based” is. A plant-based diet usually focuses on diets that include mostly foods from plant origins, such as vegetables, fruits, whole grains, seeds, nuts, and meat substitutes. That being said, eating plant-based does not mean eating only plants; it’s about prioritizing plants first and animal proteins second. Think of meat as more of a condiment of sorts instead of the main act.

What to Be Mindful Of

While vegetarian diets can have positive impacts on your health, not just potentially lowering your risk of developing colorectal cancer, it’s important to know that just because something may be classified as plant-based, it doesn’t necessarily mean it’s inherently healthy for you.

“The vegetarian or vegan dietary lifestyle may inadvertently consume high amounts of processed foods, such as certain plant-based meat alternatives and certain types of milk substitutes,” Desai explains. “Disproportionate consumption of highly processed foods, even if vegan or vegetarian, may have a negative impact on health. Therefore, it’s very important that vegans and vegetarians focus on consuming a healthy balance of whole foods and to minimize foods heavily processed to make them vegan.

“A balanced diet focused on whole food consumption with fresh fruits, vegetables, whole grains (not refined grains) and protein has been shown to greatly reduce the risks of colon cancer,” he adds. “This is a key distinction in understanding how our dietary choices, even when vegetarian or vegan, can impact our risk factors.”

If you need some guidance on how to build out a day’s worth of meals around plants, Kaylee Jacks, a sports dietitian at Texas Health Sports Medicine, outlines some helpful pointers in this previously published post.

Additionally, Desai adds that it’s important to note that while research suggests vegetarians and vegans are at lower risk, those who follow these diets aren’t completely immune to being diagnosed with colorectal cancer.

“Diet is one of the variables, but not the only variable,” he says. “We must understand the complexity of risks. Genetics, environmental factors, activity level and personal medical history can all play a role in the development of colon cancer. Implementing a diet rich in whole foods can reduce that risk, but everyone should still undergo appropriate screening and treatment no matter what their diet looks like. Regular screening greatly reduces the risks overall.”

The Takeaway

While current research looks favorably upon plant-based diets such as vegetarianism and veganism, it isn’t the only way you can reduce your risk of developing colorectal cancer. Other essential factors to consider include keeping a moderate weight, exercising, and avoiding alcohol and tobacco use.

No matter what, one of the greatest steps you can take is knowing your personal risk factors and getting the proper screening and tests done on a timeline that is appropriate for you. Because everyone’s risk for colorectal cancer can differ, you should speak with your doctor about your personal risk factors to help create a screening regimen that works best for you.

“I always suggest starting somewhere, whether it’s big or small,” Desai adds. “There is no need to change your lifestyle overnight. Focus on what is sustainable for you and stick with it. Even small steps that are sustainable will have a positive impact on your life. And always remember, there is never a better time to start than now.”

Finding a physician who can partner with you for your health is essential. We can help find a physician that’s appropriate and convenient for you. Call 1-877-THR-WELL (847-9355) or visit today.

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