Colorectal surgeon reveals 5 lifestyle habits to avoid reducing colon cancer risk

Colorectal cancer used to be a disease you worried about in your sixties or seventies. Not anymore. Over the past decade, doctors have watched younger people—people still in their forties, thirties, even twenties—show up with diagnoses that were once rare in their age group. A study by the American Cancer Society found that early-onset cases are climbing in 27 out of 50 countries worldwide. The pattern is unmistakable, and the culprit, researchers say, is not genetics or bad luck. It's what we eat and how we live.

Dr. Karen Zaghiyan, a colorectal surgeon based in Los Angeles, recently shared five specific habits she avoids—not out of paranoia, but out of what the evidence actually shows. The first is processed meat. Bacon, pepperoni, deli meat, the kind of thing that makes a sandwich convenient: studies link these to a 13 to 22 percent increase in colorectal cancer risk. The American Institute for Cancer Research went further, finding that eating just 50 grams of processed meat daily—roughly two slices of deli turkey—was tied to a 16 percent higher risk. The mechanism is straightforward. These meats are preserved with nitrates and nitrites, chemicals that can damage the cells lining your colon.

The second item on her list is charred meat. Not just grilled meat—charred meat, the kind that's been cooked over an open flame long enough to turn black. When muscle meat hits high heat or direct flame, it produces compounds called heterocyclic amines and polycyclic aromatic hydrocarbons. The National Cancer Institute notes that in laboratory animals, these chemicals have caused tumors, including in the colon. The blackening is the visible marker that these carcinogens are present. It's not that grilling is inherently dangerous; it's the char that matters.

The third factor surprised many people: antibiotics. Not the kind you take for a serious infection, but the casual use—antibiotics for a cold, for a minor sinus infection, the kind of thing that happens when you visit a doctor and walk out with a prescription you might not strictly need. Research published in PMC found that people who took antibiotics for more than two months between ages 20 and 59 had 36 to 69 percent higher odds of developing precancerous growths later in life compared to those who never took them. The reason: antibiotics don't just kill the bacteria causing your infection. They also devastate your gut microbiome, the trillions of bacteria that protect your colon's lining and regulate inflammation.

Ultra-processed foods make up the fourth category. These are not foods that have been processed—canned tomatoes, frozen vegetables, pasteurized milk. These are industrially engineered products loaded with preservatives, emulsifiers, artificial flavorings, and additives, often designed to be shelf-stable for months. They include obvious culprits like packaged snacks and fast food, but also things that feel healthier: certain baked goods, flavored yogurts, breakfast cereals. A 2025 study of nearly 30,000 women under 50 found that those eating the most ultra-processed foods had a 45 percent higher risk of developing adenomas—the precancerous polyps that can become cancer—compared to those eating the least. The problem is twofold: these foods are typically low in fiber, which your colon needs, and high in additives that can promote inflammation.

The fifth item is alcohol-based mouthwash. Many commercial brands contain ethanol at concentrations between 20 and 27 percent—higher than some beers. A 2024 study found that daily use of alcohol mouthwash for just three months significantly altered the oral microbiome, increasing levels of bacteria associated with periodontal disease, esophageal cancer, and colorectal cancer. The connection between your mouth and your colon might seem distant, but your microbiome is continuous from your lips to your intestines. What you kill in your mouth affects what thrives in your gut.

The pattern across all five factors is the same: they either introduce carcinogenic compounds directly or they disrupt the bacterial ecosystem that protects your colon. None of this means you can never eat a hamburger or take an antibiotic. It means understanding the dose, the frequency, and the cumulative effect. For younger people especially—those in their thirties and forties who might feel invincible—the evidence is becoming harder to ignore. Early warning signs include persistent changes in bowel habits, unexplained blood in the stool, ongoing abdominal discomfort, unintentional weight loss, and a feeling that you haven't fully emptied your bowels. Catching the disease early, before it spreads, transforms outcomes dramatically. The question is not whether you'll ever eat processed meat again. It's whether you understand what you're choosing when you do.