A vegetarian diet may reduce the risk for colorectal cancer in some people. A pescatarian diet, one that includes fish, may offer the most benefits.

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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 turn or evolve into cancer.

Research has long established that colon cancer is lifestyle-related and that certain dietary choices, such as diets rich in processed and red meats and refined grains, may increase the risk.

The vegetarian diet is a plant-based diet that focuses on consuming:

  • fruits
  • vegetables
  • legumes
  • grains
  • nuts
  • seeds
  • fungi
  • algae

People following a vegetarian diet may or may not also consume animal-derived products, such as eggs, dairy, or honey.

Because of these dietary choices, numerous studies and clinical trials have linked vegetarian diets to a reduced risk of colorectal cancer (CRC) compared with omnivore diets. Omnivore diets are those that include both animal- and plant-based foods.

Read on to learn more about the research behind vegetarian diet and your risk for CRC, plus other ways to reduce your risk for this type of cancer.

According to the results from a 7-year study in 77,659 people, those who followed a vegetarian diet had a 22% lower risk of CRC compared with nonvegetarians. Similarly, results from another 20-year study in 10,210 people found a significant CRC risk reduction in vegetarians compared with meat consumers.

These diets are rich in fiber

Vegetarian diets are rich in dietary fiber due to the high intake of fruits, vegetables, legumes, and whole grains. Dietary fiber is a type of carb that your body can’t digest but that still provides numerous benefits. According to research, the risk of CRC seems to increase with a low fiber intake.

In fact, evidence suggests that diets high in fiber, defined as providing over 23 grams of fiber per day, may reduce CRC risk by 12% and that for every 7 grams of fiber consumed per day, you could reduce your risk of CRC by 8%.

Furthermore, research suggests that fiber’s protective effect can improve or lessen the cancer-promoting effects of high meat intake.

Some of the beneficial effects of fiber on CRC risk include:

  • Increased stool weight: This helps dilute or trap cancer-promoting substances, which end up being excreted instead of absorbed.
  • Reduced transit time: Fiber metabolism leads to a low pH environment, which leads to stool being passed faster, reducing your bowel cells’ exposure time to potential cancerous substances.
  • Short-chain fatty acids (SCFAs) production: Fermentation of fiber releases SCFAs — namely butyrate, propionate, and acetate — which improve bowel health and have cancer-protective properties.

Some include dairy products

Lacto-vegetarian diets are a type of vegetarian diet that include dairy products, such as milk, cheese, and yogurt.

A 2019 systematic review of 29 studies in over 22,000 people found a significant CRC risk reduction with higher intakes of dairy products compared with lower consumption. Evidence suggests their protective effects against CRC come from their high levels of calcium, vitamin D, and other bioactive compounds.

The cancer-fighting properties of calcium include reducing the uncontrollable growth of cancerous cells, promoting their death, and protecting DNA from cancer-inducing damage, among others.

Vitamin D, which is present in fortified dairy products, keeps cancer cells from growing and spreading to neighboring tissues and prevents blood vessel growth, which helps starve tumors.

Additionally, yogurt and other fermented dairy products have also been linked to a reduced risk of CRC.

According to research, lactic acid bacteria in these products may improve the composition of your gut’s friendly bacteria, deactivate and reduce the absorption of cancer-promoting substances, and reduce intestinal inflammation.

They avoid red and processed meat products

Being a plant-based eating pattern, a vegetarian diet avoids the intake of animal-based proteins, including red and processed meats.

Red meats include:

  • beef
  • pork
  • lamb
  • veal
  • horse
  • mutton
  • goat

In contrast, processed meats, such as sausages or ham, are meats that have been smoked, cured, salted, or fermented to improve their flavor and extend their shelf life.

Multiple studies have found an association between higher red and processed meat intakes and a greater risk of CRC.

For example, according to a results from a 6-year study in 475,581 people, those who consumed an average of 76 grams of red or processed meats per day had a 20% increased risk of CRC than those who kept their intake at a maximum of 21 grams daily.

They’re typically low in refined carbs

Vegetarians typically center their food intake around low-calorie, nutrient-dense foods such as vegetables, legumes, whole grains, and fruits. This can lead to lower intakes of highly processed foods and refined carbs, which are high in sugar.

By choosing whole over refined carbs, vegetarians may consume fewer calories than people on higher energy diets, which in turn can help with weight control and reduce the chances of developing obesity and type 2 diabetes.

While human studies haven’t found a clear link between sugar intake and CRC risk, researchers have found an association between CRC risk, obesity, and diabetes.

Research suggests that obesity increases blood levels of sugar- and hunger-regulating hormones, as well as inflammatory markers, and reduces the levels of protective compounds. This promotes the development of CRC by facilitating the uncontrollable growth of cancer cells.

By choosing healthier foods that help you manage your weight, vegetarian diets may protect against CRC.

When it comes to vegetarianism, there’s a somewhat broad umbrella of eating patterns that range from the most flexible to the most rigid.

The six main types of vegetarian diets include:

  • 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.

While there are multiple factors involved in the effectiveness of vegetarian diets for CRC prevention and treatment, such as the intake of eggs, dairy, and fish, research suggests that certain types of vegetarian diets may offer more protection than others.

For example, compared with meat consumers, pescatarians have a 43% risk reduction, while lacto-ovo-vegetarians, vegans, and flexitarians have an 18%, 16%, and 8% lower risk, respectively.

While diet plays a critical role in the development of CRC, it isn’t the only risk factor you should be aware of.

According to the Centers for Disease Control and Prevention (CDC), nonmodifiable risk factors for CRC include:

In contrast, modifiable or lifestyle-related risk factors may include:

  • sedentary lifestyle
  • low fiber diet lacking in fruits and vegetables
  • high fat diet rich in red and processed meats
  • overweight and obesity
  • alcohol and tobacco use

While nonmodifiable risk factors, like genetics, are harder to control, improving the modifiable ones may help reduce your risk.

Aside from the dietary modifications mentioned above, which focus on reducing the intake of refined grains and red and processed meats while increasing the intake of fiber-rich foods, the CDC recommends doing at least 150 minutes of moderate-intensity physical activity per week.

This will help get your body moving and reduce the risk of obesity at the same time, both of which have been linked to a lower incidence of CRC.

Additionally, avoiding alcoholic drinks may reduce cancer risk. People assigned male at birth should aim to limit their intake to two drinks or less in a day, and people assigned female at birth to one drink or less per day.

Lastly, since tobacco use is not only linked to CRC development but also to numerous different cancers all over your body, the CDC urges people who smoke to make their best effort to quit, and advises those who don’t smoke not to start.

Regular CRC screenings are also important!

Since CRC almost always starts from abnormal growth of polyps in the large intestine, the best way to prevent CRC is to do regular screenings.

According to the CDC, CRC screening tests are designed to look for pre-cancerous polyps when a person doesn’t have any symptoms yet. They also help remove them before they become cancerous.

Additionally, they can help find cancer when it’s still in its early stages — when treatment is more likely to be more effective.

Was this helpful?

Do vegetarians get colorectal cancer?

Yes. While vegetarian diets have shown promising results in reducing the risk of cancer, vegetarians could still get CRC, and the risk may increase due to lifestyle-related circumstances, such as smoking, drinking, and leading a sedentary life.

Do vegetarians have a higher risk of cancer?

Research shows that people who follow vegetarian diets could reduce their risk of cancer by 22% compared with meat eaters.

Are vegetarians at lower risk for cancer?

According to research, vegetarians have a lower risk of CRC. This could be explained mostly due to the protective effects of their dietary choices, which include a higher intake of fiber and dairy products and a reduced intake of refined carbs, and red and processed meats.

Can a plant-based diet reverse colon cancer?

Plant-based diets are associated with numerous health benefits, such as a reduced risk of cancer, heart disease, and diabetes. However, they can’t reverse CRC. Nevertheless, according to research, reducing red and processed meats in people with CRC can help reduce the risk of cancer returning and improve overall survival in early-stage patients after standard treatment.

Colorectal cancer (CRC) is a lifestyle-related cancer that’s heavily influenced by your dietary choices. Research supports vegetarian diets as a means to reduce its risk.

While all vegetarian diets may offer protective effects due to their high fiber and low red and processed meat intake, pescatarian diets, the kind that allows for fish intake as well, seems to be the one that protects the most.

While making some dietary changes may reduce your risk of CRC, other essential factors to consider include keeping a moderate weight, exercising, and avoiding alcohol and tobacco use.