Vegan diets are on the rise for many reasons, including environmental concerns, religious and ethical principles, cultural factors, and perceived health benefits.

For a diet to be considered vegan, it must include only plant-based foods, meaning that it excludes meat, fish, eggs, dairy, and animal byproducts like gelatin and honey.

Numerous studies point to the health benefits of vegan diets, suggesting that, when followed properly, a vegan diet can help increase longevity and overall well-being.

Some research suggests that it may even help lower the risk of some cancers.

Since colon cancer is the fourth leading cause of cancer-related deaths in the United States, you may wonder whether following a vegan diet can help lower your risk.

This article explores the research into whether a vegan diet can help prevent or treat colon cancer.

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“Colon cancer” is short for colorectal cancer, which occurs when cancerous cells grow in the colon or rectum.

The Centers for Disease Control and Prevention (CDC) outlines the following risk factors for this type of 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

Although you cannot modify some of these risk factors, such as your genes and family history, you can take some actionable steps to reduce your risk. Changing your typical diet may be one of them.

There is some evidence that switching to a partially or fully plant-based diet may help prevent colon cancer.

A 2022 review of 49 studies including more than 3 million people found that plant-based diets were protective against all digestive system cancers, including colon cancer.

But keep in mind that not all the plant-based diets included in the review were fully vegan diets.

A 2015 prospective cohort study — an observational study that follows participants who belong to a certain group, such as a job or identity, over a long period of time — found lower incidences of colon cancer in 96,354 vegetarians after 7 years.

Though promising, this study is considered low quality because of a potential conflict of interest and other limitations.

Additionally, vegetarian diets, although considered plant-based, differ from vegan diets in that they may include eggs and dairy.

On that note, there’s no standard definition of “plant-based” diets in these studies, and the meaning of the term can vary widely. That means a lot of the data we have on plant-based diets and colon cancer isn’t linked to vegan diets specifically.

One review does suggest that vegans specifically may have a 15% lower risk of developing cancer overall.

And if we focus strictly vegan diets, we know that they tend to be rich in legumes, fruits, vegetables, whole grains, nuts, and seeds — all of which are high in fiber.

It’s well established that eating a high fiber diet can help reduce the risk of colon cancer and that people following vegan diets tend to eat more fiber than those who follow other dietary patterns.

Furthermore, one review suggests that legumes, which contain both fiber and cancer-fighting antioxidants, are a staple of many vegan diets. Legumes may reduce your risk of colon cancer when eaten regularly.

Plus, studies link consumption of red and processed meats to an increased risk of cancers, including colon cancer. Because plant-based diets exclude meat, vegans and vegetarians avoid red and processed meats, and this may further reduce their risk.

Keep in mind that you don’t have to go fully vegan to reap the benefits of plant-based eating. A vegan diet may not be for everyone, and it’s OK if you prefer to keep some animal proteins in your diet.

Overall, research suggests that simply adding more plant-based foods to your diet can lower your colorectal cancer risk.

You might consider reducing your intake of processed and red meats, but most poultry, fish, and dairy products are not associated with higher colorectal cancer risk.

Our best advice? Fill your bowls and plates with more plant-based foods. Enjoy legumes, whole grains, nuts, seeds, fruits, and vegetables more often.

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Unfortunately, there is no evidence that a vegan diet can treat colon cancer.

However, studies suggest that eating a vegan diet may help reduce the risk of death in people who have colon cancer.

This could be because of the increased fiber found in well-planned vegan diets.

But vegan diets may also be lower in calories than other diets. If you’re living with cancer, it’s important to make sure you’re eating enough calories and protein. You may want to eat more legumes, soy proteins, and whole grains and enjoy plenty of nuts, seeds, and oils.

Of course, be sure to discuss your diet with your cancer care team, especially if you have any questions or concerns or want to make any drastic changes, such as going vegan.

Research on cancer survivorship and nutrition is sparse, but one 2016 review found that diets high in vegetables and fish were linked with reduced risk of cancer-related death. Vegetables are, of course, prioritized in a vegan diet, while fish is excluded.

However, a more recent review found that dietary changes had little effect on rates of death among people with cancer.

Regardless of the mixed research results, the CDC encourages people with cancer to consume a diet rich in fruits, vegetables, whole grains, and lean proteins. A vegan eating pattern can provide those foods and nutrients, but it isn’t the only diet that can.

In addition to dietary changes, there are other lifestyle modifications you can make to reduce your risk of developing colon cancer.

Alcohol is a big factor. Older research suggests that excessive alcohol intake may be linked to a 50% increased risk for colon cancer.

The American Cancer Society (ACS) reports that as of 2020, alcohol use may account for 6% of all cancers and 4% of cancer deaths in the United States.

The U.S. Department of Agriculture’s Dietary Guidelines for Americans and the ACS recommend a maximum of two drinks per day for men and one drink per day for women, though the ACS maintains that it’s safest not to drink any alcohol.

Smoking is another major risk factor. If you currently smoke tobacco products, consider quitting or joining a smoking cessation program to support you in cutting back.

Exercise also plays a role. The American Institute for Cancer Research recommends getting at least 150 minutes, or 2.5 hours, of some kind of physical activity each week.

Finally, being proactive is important, as colon cancer is most treatable when caught early.

Get regular colon cancer screenings if you are over 50 years old or have an increased risk of developing colon cancer. Some experts now say that people in their 40s should get regular screenings too.

Here are some questions people often ask about vegan diets and colon cancer.

Can a plant-based diet reverse colon cancer?

Unfortunately, plant-based diets cannot reverse colon cancer. However, research suggests that following a plant-based diet may help reduce the risk of developing the cancer.

In addition, plant-based diets tend to be rich in nutrients, which are important to support the immune system in cancer survivorship.

Does being vegan lower cancer risk?

Overall, well-planned vegan diets are associated with a lower risk of cancer.

There may be several reasons for this, such as the increased fiber intake and decreased red and processed meat intake.

What is the best diet to prevent colon cancer?

The best eating pattern to prevent colon cancer is one that includes a variety of plant-based foods, such as fruits, vegetables, nuts, seeds, legumes, and whole grains.

Animal-based proteins, such as fish, poultry, and dairy, may also be included.

There are many risk factors for developing colon cancer, some of which are modifiable, which means you can change or improve them.

Research shows that eating more plant-based foods and getting enough fiber protects against colon cancer. Reducing your intake of red and processed meats can also help, and a plant-based diet excludes those foods by default.

However, to reap the rewards of plant-based eating, you don’t have to go fully vegan unless you’d like to. You can simply include more plant-based foods in your regular eating pattern.