A vegetarian diet may help reduce the risk of colorectal cancer. However, increasing fiber, fruit, and vegetable intake and limiting processed foods may help people manage their cancer risk without eliminating meat.

A vegetarian diet excludes meat from all animals, including insects. The diet can include animal products such as dairy, eggs, or honey but does not allow for byproducts of animal processing, such as gelatin or fat.

Dietary plans that completely exclude a food group may be controversial, but when it comes to preventing certain cancers, a vegetarian diet can make sense.

This article looks at how a vegetarian diet may help prevent colorectal cancer, which affects the colon and rectum in the gastrointestinal system.

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A growing body of research suggests a vegetarian diet can help lower the risk of colorectal cancer.

An older, large-scale study in 2015 found that people adhering to a vegetarian diet had a 22% lower colorectal cancer risk compared to those not on a vegetarian diet.

In 2022, a prospective analysis in the journal BMC Medicine noted the risk of developing any cancer was lowest among vegetarians, compared to meat eaters, low-meat eaters, and pescatarians — individuals practicing vegetarianism but with seafood consumption.

The researchers found that, in males specifically, vegetarianism had a link to a 43% risk reduction for colorectal cancer.

The role of meat in colorectal cancer is still under investigation. A vegetarian diet eliminates all meat, but not all meat may impact colorectal cancer risk equally.

A joint statement from the World Cancer Research Fund (WCRF) and the American Institute for Cancer Research (AICR) says there is strong evidence that consuming red meat and processed meat increases colorectal cancer risk. Some evidence indicates that consuming fish may decrease colorectal cancer risk.

A 2021 review of meta-analyses published in the journal Oncology supports the findings that red meat intake has a link to higher colorectal cancer risk, while dietary fiber, calcium, and yogurt intake may link to a lower risk.

Colorectal cancer fast facts

The American Cancer Society (ACS) states the following:

  • Colorectal cancer is the third most commonly diagnosed cancer and the third leading cause of cancer-related deaths among males and females in the United States.
  • Colorectal cancer has a 33% higher prevalence in males compared to females.
  • Alaska Native and American Indian people in the United States are the most likely to receive a diagnosis of colorectal cancer.
  • More than half of colorectal cancers link to lifestyle factors such as inactivity and poor diet.
  • A family history of colorectal cancer is the strongest risk factor for this condition.
  • Cancer risk rapidly increases with age.
  • Colorectal cancer screening rates are highest in the U.S. Northeast and lowest in the West.
  • Annually, doctors diagnose an estimated 153,020 new cases of colorectal cancer.
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Not everyone wants to give up meat to reduce colorectal cancer risk, but small dietary changes may make a big difference.

The joint statement from the WCRF and the AICR notes that certain foods and supplements may decrease colorectal cancer risk, including:

Foods that may increase colorectal cancer risk, according to the statement, include:

  • red meats
  • processed meats
  • alcohol
  • foods high in haem iron — a dietary iron found in meat, poultry, and seafood

Making several small dietary adjustments, rather than eliminating certain foods, may feel less overwhelming to a person wanting to reduce their cancer risk.

Foods for a healthy colon

The table below gives examples of foods that can contribute to a healthy colon:

Read more about cancer-fighting foods.

Diet is one way of decreasing colorectal cancer risk, but other controllable factors may also help.

People can improve their colorectal cancer risk by:

Some risk factors are not within a person’s control. Living with inflammatory bowel disease (IBD), having a family history of colorectal cancer, and certain genetic syndromes may increase colorectal cancer risk.

Part of what makes colorectal cancer so concerning is that it is often asymptomatic in the early stages.

For this reason, the ACS recommends routine screening for everyone between the ages of 45 and 75. After 75, screening happens on the basis of an individual’s needs and preferences.

Some tests, such as fecal tests, happen annually, while more invasive procedures, such as colonoscopies, happen every 10 years for people at average risk.

More frequent testing may be necessary for those who have:

  • a family or personal history of colorectal cancer
  • IBD
  • certain confirmed genetic syndromes
  • a personal history of abdominal or pelvic radiation therapy

Read about 7 alternatives to colonoscopy for colorectal cancer screening.

A vegetarian diet may help prevent colorectal cancer. Vegetarian diets are often high in fruits, vegetables, and dietary fiber and contain no red or processed meat. All of these factors affect colorectal cancer risk.

It may be possible for people to lower their colorectal cancer risk by making several dietary changes rather than eliminating food groups.

Reducing certain meats, limiting alcohol, and increasing whole grains and vegetables are small changes that may help people manage their cancer risk.