What to know about diet and risk for cancer

Cancer is a leading cause of death worldwide. But survival rates are on the rise, and many cancers can be prevented. In fact, more than 40 percent of both cancer cases and deaths in the United States are tied to controllable risk factors, according to the American Cancer Society (ACS).

Of course, some risks are beyond our control, such as age and genes. But we’re able to influence many others, such as wearing sunscreen and avoiding tobacco. We can also partly control cancer risk factors related to diet, including obesity, alcohol consumption, and the types of food we eat.

A 2024 study published in CA: A Cancer Journal for Clinicians estimated that diet-related factors were related to about 4.9 percent of cancer cases in men ages 30 and older, and 3.4 percent in women the same age. Meanwhile, alcohol consumption was related to about 4.7 percent of cancers in men, and 6.2 percent in women.

Read on to learn about foods linked to an increased risk for cancer, and foods that may help prevent cancer.

Foods associated with greater cancer risk

When it comes to diet and cancer, eating patterns matter more than any single food.

“One specific food is not going to cause cancer. But as part of an overall pattern, what you eat can increase your risk,” says Kelly K. Rashid, RDN, CSO, a clinical dietitian and certified specialist in oncology nutrition in Fort Lauderdale, Florida.

Still, certain types of foods are consistently linked to a greater cancer risk, so it’s best to take steps to limit or avoid them. These include the following.

Processed meats

Processed meats are meats that are preserved via salting, curing, smoking, or similar methods. These meats include bacon, hot dogs, ham, sausage, and deli slices, among many other items.

“Processed meats are one of the foods we have the most research on when it comes to cancer of the colon [the large intestine] and rectum [the last several inches of the large intestine],” Rashid says.

Studies tie eating too much processed meat to a 20- to 40-percent higher risk of developing colorectal cancer. “Even a small amount increases your risk,” Rashid adds. For this reason, the ACS recommends eating processed meat sparingly, if at all.

The preservation methods used to make these products may contribute to the risk. Another factor: Processed meats are often red meats. (More on that next.)

Red meat

Red meats such as beef, veal, lamb, and pork are also associated with cancer. The connection may be related to:

• The saturated fat content of many red meats. Eating too much saturated fat can lead to inflammation and weight gain. Being overweight or obese is a major risk factor for several cancers, including those of the esophagus, breast, colon, rectum, stomach, pancreas, and liver.
• The heme iron found in red meat, which may lead to the production of cancer-causing compounds
• Carcinogens (cancer-causing agents) that form when the meat is cooked at high temperatures or charred on the grill

Eating too much red meat is also tied to a higher risk of heart disease. That’s why many leading health organizations, including the ACS and American Heart Association (AHA), recommend opting for lean proteins instead, such as chicken breast, fish, beans, and tofu. If you do eat red meat:

• Choose leaner cuts and trim off fat when you can.
• Be aware of your overall saturated fat intake. The AHA recommends no more than 13 grams for a person who eats 2,000 calories each day.
• Eat moderate portions. A single serving is 3 ounces, or about the size of a deck of cards.
• Limit cooking time if you’re grilling. Pre-cooking in a microwave, oven, or stove can help.

Alcohol

Alcohol is a significant risk factor for cancers of the breast, colon, rectum, esophagus, throat, and mouth. For example, it’s tied to almost half of oral cancers in men and about one-quarter in women.

Even one alcoholic drink per day significantly raises the risk of developing many types of cancer. And the more you drink, the higher your risk.

There are several potential explanations for the link. It’s believed that the ethanol in alcoholic drinks may directly cause cancer. Alcohol may also increase the ability of other carcinogens to enter your body’s cells and cause changes that lead to cancer. It could raise levels of the hormone estrogen, as well, and influence your body’s ability to absorb folate, a key nutrient that helps protect against colon cancer.

Your genes, medical history, weight, and lifestyle will also play roles. But when it comes to cancer prevention, avoidance of alcohol is the best bet. If you do drink alcohol, don’t exceed guidelines for light or moderate drinking: No more than two drinks daily for men, and one drink per day for women.

Sugar

Sugar has not actually been found to directly increase cancer risk, but there is an indirect link. “Sugar in general does not provide any nutritional value, and it causes obesity—and obesity is linked to at least 12 different types of cancer,” Rashid explains.

“If you drink a sugary beverage on a special occasion, is it going to cause you cancer? No,” Rashid adds. “But the risk increases if you consume excess calories and sugar, and it causes obesity. There are also a number of other health concerns associated with sugar-sweetened beverages.” These include a higher risk of type 2 diabetes and heart disease.

The ACS advises limiting added sugar. The AHA recommends that it make up no more than 6 percent of your calorie intake each day. For many healthy adult men, that works out to around 150 calories daily. For women, it’s 100 calories.

Foods linked to lower cancer risk

While some foods are tied to higher cancer risk, many others are tied to lower risk—and you may be eating them already.

“The recommendations for a healthy, cancer-prevention diet are not really different at all from your standard dietary recommendations,” Rashid points out. They include the following foods, many of which come from plant sources.

Whole grains

Whole grains are essential sources of dietary fiber. Not getting enough fiber can increase your cancer risk. In fact, a low-fiber diet is associated with roughly 10 percent of all colorectal cancer cases, according to the ACS.

Eating whole grains such as brown rice, oatmeal, and whole wheat bread can ensure you get enough fiber, along with other key nutrients that could help lower the risk of cancer. The ACS recommends eating whole grains as part of a healthy overall diet, and the AHA advises getting about three servings each day.

Fruits and vegetables

Produce also contains plenty of fiber. Eating a range of colorful fruits and veggies supports healthy weight management, as well, and provides phytochemicals—plant compounds that may reduce the risk of certain cancers, including lung cancer and oral cancers.

“Different color groups have different types of phytochemicals, and they work in different ways to fight off cancer,” says Rashid.

Legumes

Like produce and whole grains, legumes (beans, peas, and lentils) are plant-based foods that are rich in fiber. Legumes are also good sources of protective nutrients like folate, as well as protein, which makes them excellent substitutes for red meat. Try swapping them into soups, stews, chilis, and other main dishes in place of ground beef or pork.

Dairy

“There’s a lot of mixed research with dairy,” says Rashid. For example, some research suggests diets high in calcium and dairy products are linked to a lower colorectal cancer risk, while other studies have found dairy is tied to a greater risk of prostate cancer. Because of this, the ACS doesn’t make specific dietary recommendations for dairy. Talk to an HCP about how dairy intake might affect you. If you do eat dairy foods, many experts suggest choosing low-fat or fat-free options.

Fermented dairy products often contain beneficial bacteria called probiotics, which some research suggests are associated with lower cancer risks. Good sources of these microorganisms include yogurt with live, active cultures and kefir, a drink made from fermented cow's milk. Probiotics are also found in other non-dairy fermented foods like pickles, sauerkraut, and kimchi.

Make healthy choices when you can

You don’t have to give up the foods you love entirely. But it’s good to be aware of which ones to emphasize and which ones to limit. It comes down to variety, portions, and making healthy choices when you can.

“I would never tell someone they can’t ever have certain foods or never use their grill again. Just try to save them for special occasions,” says Rashid. “We want more of a plant-based diet. It doesn’t have to be plant-only, but you should focus on more plant foods and less on processed or animal products.”