Registered dietitians weigh in on what the research says—and what to eat instead.

Reviewed by Dietitian Jessica Ball, M.S., RD

Key Points

• Eating processed meats like bacon or hot dogs regularly may increase colorectal cancer risk.


• Diets high in added sugars, especially from sweetened drinks, can harm gut health.


• Whole grains and fiber-rich foods help lower risk and support gut health.

Colorectal cancer is the second leading cause of cancer- deaths in the United States, and researchers are paying closer attention to a factor that may be contributing to its rise: what we eat. Cases among adults under 50 have been climbing steadily for decades, a trend that experts increasingly link to the modern Western diet. The good news is that up to 55 percent of colorectal cancers may be preventable through diet and lifestyle changes, which means the choices you make in the grocery store genuinely matter.

That doesn't mean we should let every alarming headline about food and cancer dictate what ends up on our plates. What the evidence does show is that eating certain foods regularly, and in generous amounts, is linked to a meaningfully higher risk. Knowing which foods can increase your risk and understanding the reasons why puts you in a stronger position to make choices that can protect your health for the long run.

1. Processed and Deli Meats

Hot dogs, salami, bologna and bacon sit at the top of the evidence-based concern list when it comes to processed meats. Deli-sliced turkey and roast beef are also technically classified as processed (since they're cured and preserved with sodium), though the research linking them to elevated colon cancer risk is considerably less robust. The World Health Organization’s International Agency for Research on Cancer (IARC) classifies processed meat as a known human carcinogen and red meat as a probable carcinogen, based on evidence linking both to colorectal cancer. Studies suggest that regularly eating processed and red meats may increase colorectal cancer risk. Experts believe this may be due to certain preservatives and compounds that form during cooking, which can damage cells in the digestive tract.

When you eat processed meats preserved with nitrates or nitrites, your body may convert those compounds into N-nitroso compounds (NOCs), which can damage the cells lining the bowel. High-temperature cooking methods like frying, grilling or smoking can create additional carcinogenic compounds called heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) that may further elevate the risk.

The practical takeaway is not that you should always pass up the prosciutto or skip a summer hot dog. It's that making processed meats a daily part of your diet can carry real and cumulative consequences. Swapping them most of the time for poultry, fish, legumes or eggs is one of the most evidence-backed shifts you can make. As Angie Boxberger, M.S. RD CSO puts it, "Processed meats are best eaten as minimally as possible—more of a 'sometimes' food rather than something in your regular rotation."

2. Ultra-Processed Packaged Foods

Ultra-processed foods (UPFs) seem to be everywhere in nutrition news these days, but figuring out exactly what counts as a UPF isn't always easy. Packaged cookies, crackers, frozen meals, sweetened breakfast cereals, flavored chips and fast food all fall under that umbrella, and they've become a major focus in colorectal cancer research. Karen Collins, M.S., RDN, CDN, FAND, explains, "Ultra-processed foods are products that are made using industrial methods to break down whole foods and combine them with other substances not typically used in home cooking." Collins went on to say, "Not all UPFs show the same association with risk of cancer and other health problems, and research is starting to differentiate among types of UPFs instead of grouping them all together."

Collins advises, "More research is needed to pinpoint which types of UPFs and UPF ingredients are most concerning." In other words, it's best not to jump to judgment and it's worth noting that the risk appears to be dose dependent. You do not have to eliminate every packaged food from your kitchen, but the research suggests the more ultra-processed foods dominate your diet, the higher the potential risk. Collins concludes, "The best advice is to check the figures on the Nutrition Facts panel on food labels and focus first on cutting back on UPFs that are low in nutrient value and high in added sugar, salt or fat. Small reductions can add up and support better health."

3. High-Added-Sugar Foods

Packaged sweets, sweetened breakfast items, flavored yogurts, energy bars, sauces and condiments high in added sugar may work against colon health. We often associate the negative effects of excess sugar intake with heart health and diabetes, but when it comes to colon cancer, the story is a bit more nuanced. Boxberger tells us, "The research doesn't show that sugar directly causes colon cancer, but it does show that higher intake of added sugars, especially from sugar-sweetened beverages like soda or sweet tea, is associated with a modest increase in colorectal cancer risk." This link is especially notable in younger adults. Boxberger points out that in one large study, women who had two or more sugar-sweetened drinks per day had more than double the risk of early-onset colorectal cancer compared to those who rarely drank them. Boxberger clarifies, "That doesn't mean sugar is the sole cause, but it's likely one piece of a bigger picture."

What's happening physiologically, Boxberger explains, is that "Added sugar can weaken the gut lining: Think of your intestinal lining as a protective barrier that's meant to keep things where they belong. Diets high in added sugar can make that barrier a bit 'leakier,' which allows inflammatory compounds from the gut to slip into circulation." That low-grade inflammation is one of the processes linked to colon cancer risk.

"Added sugar can shift your gut microbiome. When there's a steady stream of added sugar, it tends to feed the less helpful bacteria and crowd out the ones we actually want more of—especially the ones that produce compounds like butyrate. Butyrate is a big deal for colon health because it helps keep the cells of your colon strong, stable and less prone to abnormal growth," Boxberger says.

Lastly, Boxberger tells us, "Added sugar can wear down the mucus layer that lines the colon." This layer acts like a buffer between your gut bacteria and your intestinal wall. In other words, Boxberger warns, "When it thins out, bacteria can get a little too close for comfort, which can trigger more irritation and inflammation over time." Boxberger highlighted that even though individually, these changes might seem small, together they create an environment that's more inflamed, less protected and more vulnerable.

Too much added sugar in the diet can also lead to weight gain, which can make it harder for the body to regulate blood sugar, which may play a role in colon cancer development.

Boxberger's takeaway is, "A more helpful takeaway is to look at where added sugars are coming from, especially sweetened drinks, and make sure they're not crowding out foods that support gut health, like fiber-rich plants."

4. Refined Grains

White bread, white rice, white pasta and refined grain cereals are not inherently dangerous foods, but they are lacking something essential: fiber. When grains are refined, the outer bran layer that contains most of the fiber, vitamins, minerals and phytocompounds is removed. Fiber is not just a digestive aid; it is one of the most consistently protective dietary factors against colorectal cancer identified in the research. The American Institute for Cancer Research (AICR) reports that eating approximately three servings (90 grams) of whole grains daily is associated with a 17 percent reduction in colorectal cancer risk.

Fiber works in several ways. It accelerates the movement of waste through the colon, reducing the time potential carcinogens spend in contact with the colon wall. It also feeds beneficial gut bacteria, which produce short-chain fatty acids (SCFAs) that have anti-inflammatory and anti-cancer properties. Whole grains also contain compounds such as polyphenols, lignans, selenium and vitamin E that may help protect cells from damage and have been linked to potential anti-cancer effects in laboratory studies.

Making the switch from refined grains to whole grains is one of the most recommended dietary changes for colon health. That might be as simple as having whole-grain cereal for breakfast and whole-grain bread at lunch. Collins suggests, "If you're not used to the flavor, start by mixing whole and refined grains or incorporating options like quinoa, farro or brown rice into your favorite dishes."

5. Red Meat (When Eaten in Excess)

Red meat, including beef, pork, lamb and veal, is classified by the IARC as "probably carcinogenic to humans" (Group 2A), a distinction worth understanding. This classification is based on large population studies showing that higher red meat consumption is associated with increased colorectal cancer risk, even though not all studies are entirely consistent.

Research found that eating 76 grams (about 2.7 ounces) of red or processed meat daily increases colon cancer risk by approximately 20 percent. Considering that a 'small' steak in a steakhouse weighs in at around 8 ounces, the amount referenced may be smaller than many people realize. Boxberger suggests, "As a general guideline, keeping red meat to around 1 to 2 servings per week (with a serving being about 3 to 4 ounces, or roughly the size of a deck of cards) is a reasonable target."

The concern with red meat isn't just how much you eat, but also how it's prepared. Researchers believe that compounds naturally found in red meat, along with substances that form when meat is grilled, charred or cooked at very high temperatures, may contribute to colorectal cancer risk. That doesn't mean you need to give up meat altogether. Instead, experts recommend limiting red meat to about three servings per week and choosing plant proteins such as beans, lentils and tofu more often.

Other Tips for Lowering Colon Cancer Risk

Diet is not the only lever you can pull. A combination of food choices, lifestyle habits and proactive screening makes for the strongest protection against colorectal cancer. Here are some of the most evidence-backed steps:

• Get screened on schedule. The American Cancer Society recommends that people at average risk begin colorectal cancer screening at age 45. Many cancers and precancerous polyps can be caught and treated well before symptoms appear. Talk to a healthcare provider about which type of screening test is right for you.


• Load up on vegetables and legumes. A diet rich in colorful vegetables, fruits, beans and lentils supplies fiber, antioxidants and phytochemicals that actively protect the colon. Plant-forward dietary patterns are associated with significantly lower colorectal cancer risk.


• Stay physically active. Regular physical activity reduces colorectal cancer risk through multiple pathways, including reduced inflammation, improved insulin sensitivity and healthier body weight. The American Cancer Society recommends at least 150 to 300 minutes of moderate-intensity activity per week.


• Maintain a healthy weight. Excess body fat, particularly around the abdomen, is an independent risk factor for colorectal cancer. Obesity is associated with higher levels of insulin and insulin-like growth factors, which can promote tumor cell growth.


• Limit alcohol. Alcohol is an established risk factor for colorectal cancer, and the evidence points to no truly "safe" level. If you drink, the recommendation is to limit consumption as much as possible.

Our Expert Take

The foods most consistently linked to higher colorectal cancer risk, such as processed meats, ultra-processed packaged foods, high-added-sugar items, refined grains and excess red meat, share a common thread: they tend to promote inflammation, disrupt the gut microbiome and lack fiber and protective compounds that help keep the colon healthy. The research is clear that no single food is a guaranteed path to cancer, and no single meal defines your risk. What matters is the overall pattern of eating, sustained over time.

The most protective diet for colon health looks a lot like what nutrition science has recommended for decades: plenty of vegetables, fruits, whole grains, legumes, healthy fats and lean proteins, with processed and red meats playing a smaller, occasional role. These choices also support a diverse gut microbiome and lower systemic inflammation, two factors that extend well beyond cancer prevention.