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The #1 Cause of Colon Cancer, Say Experts

This is the main cause of colon cancer, according to science.

Colon cancer is the third leading cause of death for people in the U.S., according to the CDC. While a small percentage (5-10%) of colon cancer is thought to be hereditary, lifestyle factors play a significant role—here is the #1 cause of colon cancer, according to the experts. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Sedentary Lifestyle

woman watching t

A sedentary lifestyle is a huge risk factor for colon cancer: For example, there is evidence that men who watch more than four hours of TV a day have a greater risk of colon cancer than those who watch less than an hour. "Previous research suggests that watching TV may be associated with other behaviors, such as smoking, drinking and snacking more, and we know that these things can increase the risk of bowel cancer," says Dr. Neil Murphy, lead researcher based at the International Agency for Research on Cancer in France. "Being sedentary is also associated with weight gain and greater body fat. Excess body fat may influence the blood levels of hormones and other chemicals which affect the way our cells grow, and can increase bowel cancer risk."

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Poor Diet

holding burger

According to Stanford Healthcare, a plant-based, high-fiber diet that limits red meat, processed meat and alcohol has been shown to reduce colorectal cancer risk. "It just goes back to what we've been learning over time," says colorectal surgeon Scott Steele, MD. "The Mediterranean Diet is a really healthy diet. It keeps us from developing things such as colon and rectal cancers, heart disease and other diseases."

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Alcohol Consumption


Research shows that people who have three and a half alcoholic drinks per day are 50 percent more at risk of developing colon cancer compared to people who drink lightly or abstain altogether. "If you look at alcohol as a drug, it can have a really significant effect, not just on your colon," says Dr. Mark Pochapin, professor and director of the division of gastroenterology at NYU Langone Medical Center. "It's a total body thing. You don't have to be dying in the gutter to be an alcoholic. I ask patients when their last drink was. If they can tell me the day and time, alcohol has a significant effect on their life. There are plenty of people who don't recognize they're addicted to alcohol."

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Being Overweight or Obese

Female leg stepping on floor scales

Being overweight or obese is strongly linked to developing colon cancer, especially in adolescents. "In order for cancer cells to grow and persist, they need fuel," says Suzana Savkovic, PhD, associate professor of pathology and laboratory medicine. "Overweight or obese individuals store excess energy in the form of fat, and cancer cells derive their energy from muscles and fat. So, we know obesity and cancer progression are connected, but we don't yet fully understand how."

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Heavy Tobacco Use

cigarette in man hand with smoke

Research has shown that smokers are more likely to develop colon cancer: one study showed that smoking doubled the risk of colorectal polyps, which are strongly correlated with colon cancer. "While the harmful health effects of tobacco smoking are well known, smoking has not been considered so far in the stratification of patients for CRC screening. Our findings could support lowering the recommended age for smokers to receive colorectal cancer screening," says Albert B. Lowenfels, MD, from New York Medical College, Valhalla, New York. 

"We observed approximately a 50% increase in colon cancer risk from smoking over a pack of cigarettes per day among both men and women," according to another paper published in the International Journal of Cancer. "Those who stopped smoking remained at increased risk, even if they stopped over 10 years ago. Our data suggest that the amount smoked may be a more important factor than the total number of years smoked."

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Colorectal Screening Saves Lives

Portrait of a mature female doctor standing in a hospital.

The #1 cause of colon cancer is lifestyle factors—but the risk can be lessened by making specific lifestyle changes and getting screened regularly, beginning at age 45. According to the CDC, approximately nine out of 10 people whose colorectal cancers are found early and given the appropriate treatment are still alive five years later—make sure to speak to your health provider if you have any concerns or questions about colon cancer. 

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Ferozan Mast
Ferozan Mast is a science, health and wellness writer with a passion for making science and research-backed information accessible to a general audience. Read more about Ferozan
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