Vegetarian diet linked to lower colon cancer risk

Heidi Godman
Heidi Godman, Executive Editor, Harvard Health Letter

Red meat is off the table in my house. It’s not that we don’t like eating it — we definitely do. It’s just that eating red meat has been linked with an increased risk of colorectal cancer. Since this type of cancer runs in my husband’s family, we pass on pot roast and prime rib, and use turkey for tacos and burgers. Now, a new study suggests that we should go entirely meat free, but add more fish to reduce our risk even further.

Meatless meals

For the study, researchers at Loma Linda University in California analyzed the dietary habits of more than 70,000 people. Those who ate a vegetarian diet had a 22% lower risk of colorectal cancer than those who weren’t vegetarians. Among those who ate a vegetarian diet that included fish, the reduction in risk was even greater — 43%. A vegetarian diet that includes fish and other seafood is called a pescovegetarian diet.

Keep in mind that the study didn’t show that a vegetarian diet caused this lower risk, just that diet and risk were associated. The results were published online in JAMA Internal Medicine.

How might a vegetarian diet work some magic against colorectal cancer? “These dietary patterns may decrease insulin and insulin-like growth factors, two hormones linked to colorectal cancer, compared to the traditional American diet,” says Dr. Edward Giovannucci, a professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health.

There are other ways a vegetarian diet may protect against colorectal cancer:

  • It’s possible that something in red meat or the way it is cooked encourages the growth of colorectal cancer. That goes double for processed red meats.
  • Eating more plant foods provides extra beneficial nutrients such as folate, calcium, and fiber that may protect against colorectal cancer.

And what about the increased protection linked to eating fish? “Fish contain omega-3 fatty acids, which may be anti-inflammatory. In addition, while a vegetarian diet has many good aspects, it may be low in vitamin D; fish is one of the few natural dietary sources of vitamin D,” says Dr. Giovannucci. Higher intake of vitamin D has been linked to lower colorectal cancer risk.

Why it’s a big deal

Colorectal cancer is the second leading cause of cancer death in the United States. The name refers to cancer of either the colon, also known as the large intestine, or of the rectum, the last six inches of the digestive system.

There’s no way to prevent colorectal cancer entirely, but there’s a lot you can do to help ward it off, like maintaining a healthy weight, not smoking, drinking alcohol in moderation (if at all), and exercising. Simply changing your diet is worth noting as another strategy for preventing colorectal cancer.

Dietary changes

Should you cut out red meat, like my family has? “The lower the red meat intake the better, especially for processed meats. It may be difficult for some people to cut it out completely, but I would encourage them to at least reduce the amount they eat,” says Dr. Giovannucci. He suggests no more than two 3-ounce servings of red meat per week.

If you’re interested in cutting out meat for good, make a gradual shift toward more plant-based protein (legumes, nuts, seeds, whole grains) over a six-month period. Stop building your meals around a hunk of chicken, beef, or pork. Put a variety of plant-based proteins on your plate and enjoy the combinations.

Since you’re already making a dietary change, make the most of it by cutting back on foods that spike blood sugar, such as refined grains and sugary snacks and drinks. Too much blood sugar forces your body to make more insulin, the hormone that helps cells use energy, and insulin has a growth-promoting effect on cancer.

Get tested

Colorectal cancer is one of the easiest cancers to treat if it’s caught very early. That’s why regular testing is so important. The National Cancer Institute recommends colonoscopy screenings for all adults starting at age 50, with follow-ups every 10 years, or more often if your personal risk for cancer is higher. People with a parent or sibling who had colon cancer should begin testing before age 50.


  1. Doctor Today Healthcare

    Hey, Thanks for posting these are very helpful information for all.

  2. Anna-Jo

    Good foods for Good diet. I believe that good food is organic food without materials harmful to the body. therefore, this means that the Organic food is good for a good diet.

  3. Asian Clinic

    I agree with bard callagge that any diet that includes fish is not a “vegetarian” diet. Anyways Beneficial information for those having more intake of Red meat, Become a vegetarian as you all know ‘prevention is better than cure!’

  4. bard callagge

    “Among those who ate a vegetarian diet that included fish, the reduction in risk was even greater”…

    Any diet that includes fish is not a “vegetarian” diet.

  5. Nguyen Chien Thang

    thank you , i love this content

  6. Yeny Tresnawati

    yes it is true, the cancer is not treated should be avoided. But we never know that cancer can strike at any time. But if we can maintain a good diet, I’m sure all of it is not going to happen.

    by : obat asam urat

  7. Prasanta Kumar Ganguly

    My father suffered from colon cancer in 1998,so this information is very important to me.

  8. Student Loan Relief

    Thanks for posting, these are very helpful information. You are helping people to be more aware about colon cancer.

  9. vaishnavi

    In general for any cancer meat sometimes turns out to be a carcinogen so its better to give up meat those who eat, so that we can overcome another risk.

  10. Georgia

    What is the importance of the food pyramid in fighting cancer?

  11. Lala Ji

    Thanks for sharing a nice and useful information.

  12. Desmond Solomon

    Very helpful:
    I have an enlarged prostate that causes me to urinate often (8 to 10 times daily), and burns while urinating. i have to see the Urologist next week, and hope he does not think about operating.
    The swollen prostate gland has shrunk due to the following:
    I have used fresh frozen cranbury blended in a blender, and lightly mixed with water no sugar, and within one week i noticed the burning sensation was gone urine output increased by 30%..
    I also did an exercise in the area of the prostate between the anus, and the penis placing my finger between them, and feeling the contraction that i create, that help to strengthen the muscles that control urine, and sperm output, plus stronger penis erection resulting in increased ability to control urine output.
    Older people loose a lot of muscle mass; i think many problems are due to weak muscles even snoring; never stop exercising.
    Note This is not copied from anyone.
    With respect,

  13. Ara Nahapetian, ScD

    I confirm the findings.

  14. mani

    Thanks for sharing a nice and useful information. good post sir keep it up 🙂