What you can do to reduce your risk of colorectal cancer

It’s a success story. The death rate from colorectal cancer in 2016 was less than half of what it was in 1970. One troubling sign: while colorectal cancer is dropping in older adults, it’s inching up in adults younger than 55.

You have a higher risk if you:

  • are 50 or older
  • have excess weight
  • are sedentary
  • eat processed or red meats often
  • have a parent, brother, sister, or child who was diagnosed with colon cancer
  • have ever had colon polyps
  • have ulcerative colitis or Crohn’s disease
  • have type 2 diabetes
  • smoke tobacco

Diet, exercise, etc.

“It’s so frustrating that colorectal cancer is still such a massive killer around the world, because there is so much we can do to reduce the incidence,” says Amanda Cross, a cancer epidemiologist at Imperial College London.

Your first step: get a colonoscopy or another screening test.

“Screening has had a dramatic effect on the incidence of colorectal cancer in those over age 50,” says Cross. “Before screening, the incidence was increasing. Now it’s coming down.”

And stay in shape. “If you’re active and not overweight, your risk is lower,” says Cross. Healthy insulin levels may help explain why.

“Physical activity increases insulin sensitivity, which can curb high insulin levels,” she explains.

Excess weight often leads to excess insulin, but people with higher insulin levels have a higher risk even if they’re lean.

More than two servings of alcohol a day for men—or one for women—is also a risk factor. The acetaldehyde that’s made when the body metabolizes alcohol may be carcinogenic to cells lining the colon.

In 2015, the International Agency for Research on Cancer concluded that each daily (3½ oz.) serving of red meat or (2 oz.) serving of processed meat like bacon, ham, sausage, or hot dogs is linked to roughly an 18 percent higher risk of colorectal cancer. The evidence was stronger for processed meat.

Carcinogenic N-nitroso compounds may be partly to blame.

“Companies now add less nitrite and add ascorbic acid to processed meats to inhibit the formation of N-nitroso compounds, but they can still form in the body,” says Cross.

Meat may harbor other carcinogens. “There is evidence from animals that two other groups of compounds—heterocyclic amines and polycyclic aromatic hydrocarbons—are carcinogenic,” says Cross. “And both are found in processed and unprocessed red meats cooked at high temperatures.”

Warning signs

Diarrhea or constipation, feeling that your bowel doesn’t empty completely, blood (bright red or very dark) in your stool, rectal bleeding, narrow stools, gas pain, cramps, feeling full or bloated, unintended weight loss, fatigue, decreased appetite.

Photo: Monkey Business/stock.adobe.com.

The information in this post first appeared in the April 2019 issue of Nutrition Action Healthletter.

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