Screening recommendations vary by country and individual risk. In the United States, for example, average-risk adults are generally advised to begin colorectal cancer screening at age 45 and continue through age 75. Screening decisions for adults aged 76 to 85 are individualized.

Other countries may use different starting ages, testing methods, and screening intervals.

People with a family history of colorectal cancer, certain hereditary syndromes, previous colorectal polyps, or inflammatory bowel disease may need earlier or more frequent evaluation.

Several screening methods are available.

1. Fecal immunochemical test (FIT)

FIT detects small amounts of human blood in stool. It is noninvasive and can usually be completed at home using a collection kit.

If the result is positive, a colonoscopy is generally needed to determine the source of bleeding.

2. Stool DNA testing

Some tests combine the detection of hidden blood with the identification of abnormal DNA markers associated with colorectal cancer or precancerous growths.

These tests can be useful screening options for certain average-risk adults, but a positive result requires follow-up colonoscopy.

3. Colonoscopy

Colonoscopy allows a healthcare professional to examine the inside of the colon using a flexible instrument equipped with a camera.

During the procedure, doctors can identify abnormalities, take tissue samples, and remove certain polyps.

Because colonoscopy can both detect and remove precancerous growths, it plays an important role in colorectal cancer prevention.

4. Flexible sigmoidoscopy

This procedure examines the lower portion of the colon and rectum. It can identify abnormalities in the area examined, although it does not evaluate the entire colon.

5. CT colonography

Also called virtual colonoscopy, this imaging test uses computed tomography to create detailed images of the colon.

It can identify certain abnormalities, but suspicious findings generally require a conventional colonoscopy for further evaluation.

No screening test is perfect. The appropriate method depends on age, personal medical history, family history, availability, and individual preferences.

Most importantly, screening is intended for people who do not have symptoms. Someone experiencing concerning symptoms may need diagnostic testing even if they are younger than the usual screening age or recently had a negative screening test.

Chapter 8: Everyday Habits That Support Colon Health

Although no lifestyle routine can guarantee protection against every colon-related disease, several habits can support digestive health and may reduce the risk of colorectal cancer.

The goal is not to follow an extreme diet or rely on expensive supplements. Consistent, practical habits are generally more useful.

1. Eat More Fiber-Rich Foods

Dietary fiber supports regular bowel movements and helps maintain healthy digestive function.

Good sources include:

• Whole grains such as oats and brown rice.

• Beans, lentils, and chickpeas.

• Broccoli, carrots, and leafy green vegetables.

• Apples, pears, berries, and oranges.

• Nuts and seeds.

Fiber helps increase stool bulk and can make bowel movements easier to pass.

However, increasing fiber too quickly may cause gas and bloating. People who currently eat very little fiber should increase their intake gradually and drink enough fluids.

Individuals with certain intestinal conditions or suspected bowel obstruction may require specific dietary advice from a healthcare professional.

2. Stay Properly Hydrated

Water helps the body maintain normal digestive function.

When fluid intake is insufficient, stool may become harder and more difficult to pass, potentially contributing to constipation.

Daily fluid requirements vary depending on body size, climate, physical activity, diet, and medical conditions.

Drinking water regularly throughout the day is generally more useful than waiting until intense thirst develops.

People with heart, kidney, or other conditions that require fluid restrictions should follow their healthcare professional's recommendations.

3. Limit Processed Meat and Moderate Red Meat Intake

Processed meats include bacon, sausages, hot dogs, ham, and certain cured or smoked meats.

The International Agency for Research on Cancer classifies processed meat as carcinogenic to humans, based on evidence linking its consumption with colorectal cancer.

This classification describes the strength of evidence that a substance can cause cancer, not the level of risk associated with a single serving.

Red meat, including beef, pork, and lamb, is classified as probably carcinogenic to humans.

Reducing processed meat consumption and choosing a greater variety of protein sources may support long-term health.

Alternatives include fish, poultry, beans, lentils, tofu, and other plant-based proteins.

4. Maintain Regular Physical Activity

Physical activity supports bowel function, helps maintain a healthy body weight, and contributes to overall metabolic health.

Walking, swimming, cycling, dancing, and other moderate activities can be useful options.

Adults are generally encouraged to aim for at least 150 minutes of moderate-intensity aerobic activity each week, along with muscle-strengthening activities on two or more days.

People who have been inactive for a long time should begin gradually and increase activity according to their abilities.

5. Avoid Smoking and Limit Alcohol

Smoking is associated with an increased risk of colorectal cancer and many other serious diseases.

Alcohol consumption is also linked to colorectal cancer risk, with risk generally increasing as alcohol intake rises.

Avoiding tobacco and limiting alcohol can improve overall health while reducing exposure to known risk factors.

6. Maintain a Healthy Body Weight

Excess body fat, particularly around the abdomen, is associated with an increased risk of colorectal cancer.

Maintaining a healthy weight through balanced eating, regular movement, and adequate sleep can support long-term health.

The focus should be on sustainable habits rather than rapid weight-loss methods.

7. Do Not Ignore Screening Recommendations

Even people who eat well, exercise regularly, and have no digestive symptoms may still develop colorectal polyps or cancer.

Lifestyle choices are important, but they do not replace screening.