What to know about diet and risk for cancer

The foods you avoid are just as important as the ones you eat.

platter of sausages

Updated on April 3, 2024.

Cancer is a leading cause of death worldwide. While more and more people are alive today after being diagnosed with cancer, many cases are preventable. In fact, in the United States, roughly 42 percent of all cancers and 45 percent of cancer deaths are tied to risk factors that are considered to be controllable (within someone's capacity to change), according to the American Cancer Society (ACS).

While some factors that increase the risk for cancer can’t be changed, like age and genes, many other risk factors may be controllable, such as wearing sunscreen or quitting tobacco if you smoke. Other cancer risk factors that are considered controllable include obesity, drinking alcohol, and diet.

A May 2019 study published in the Journal of the National Cancer Institute Cancer Spectrum estimated that dietary factors accounted for 80,110—or 5.2 percent—of new diagnoses of invasive cancers (those that have spread beyond the initial tumor) in adults in 2015. Alcohol consumption may contribute a similar percentage to cancer risk.

Read on to learn about foods that are associated with increased risk for cancer, and foods that may help prevent cancer.

Foods associated with cancer risk

When it comes to diet and cancer, eating patterns, not just individual foods, may make a difference.

“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 at Holy Cross Hospital in Fort Lauderdale, Florida.

Certain types of food, in particular, have been associated with an increased risk of cancer, so it’s best to take steps to limit or avoid them. Some of these include:

Processed meats: Many studies have tied excessive intake of processed meats to a higher risk for bowel (colorectal) cancer, boosting the risk by as much as 30 percent. “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. These include cured, smoked, or salted meats. Scientists don’t yet know why there’s such a strong link, but the preservation methods used to make these products may be what increases the risk of cancer. Also, processed meats are often red meats, which may be another factor (more on that next).

“Even a small amount increases your risk,” Rashid adds. Limit your intake of preserved meats as well as bacon, bologna, hot dogs, and deli meats—or avoid them entirely. The same rules apply for other ultra-processed foods, like packaged snacks and frozen meals. These products have also been tied to an increased risk for cancer.

Red meat: Beef, veal, lamb, and pork are also associated with colorectal cancer. In fact, ACS researchers suggest red meats like these are associated with 5.4 percent of all cases. Although experts aren’t sure why, the connection may be related to the animal fat or heme iron (type of iron found in meat that is more easily absorbed by your body) that red meat contains, or to carcinogens (cancer-causing substances) that form when the meat is cooked at high temperatures or charred on the grill.

You don’t have to cut red meats out of your diet completely, but moderation is key. For the purposes of cancer prevention, it’s a good idea to limit your intake to no more than about three portions per week, or about 12 to 18 ounces cooked, according to the American Institute for Cancer Research (AICR). It’s also wise to opt for lean cuts of beef, trim off fat when you can, and limit cooking time if you’re grilling (pre-cooking in a microwave, oven, or stove can help), according to the AICR.

Alcohol: Alcohol—especially heavy drinking—is linked to an increased risk for several types of cancer. A 2018 review published in The Lancet showed that even one alcoholic drink per day could increase the risk for cancer of the breast, colon and/or rectum, esophagus (the tube that carries food from your mouth to your stomach), pharynx (throat), and mouth. And a 2021 World Health Organization study concluded that 4 percent of cancers around the world may be caused by alcohol. Essentially, any amount of alcohol increases your cancer risk. And the more you drink, the higher your risk.

Multiple explanations for this connection exist. It’s believed that the ethanol in alcoholic drinks may directly cause cancer, and that alcohol may also increase the ability of other carcinogens to enter your body’s cells and cause changes that lead to cancer.

Alcohol may also raise levels of the hormone estrogen 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 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.”

When it comes to added sugar, stick to the 2020-2025 Dietary Guidelines and limit your total intake to less than 10 percent of your daily calories.                                                      

Foods associated with cancer prevention

The good news is that many foods have been associated with cancer prevention, and a diet rich in these types of foods can be delicious and healthy for a variety of reasons.

“The recommendations for a healthy, cancer-prevention diet are not really different at all from your standard dietary recommendations,” Rashid points out.

Start by basing your meals on plant-based food sources, according to the ACS. This includes things like:

Fruits and vegetables: These contain cancer-fighting nutrients called phytochemicals. A diet rich in many differently colored fruits and vegatables may reduce the risk of certain cancers, include oral cancers as well as lung cancer. “Different color groups have different types of phytochemicals, and they work in different ways to fight off cancer,” says Rashid.

Diets low in fruits and vegetables are linked to roughly 17 percent of oral and throat cancers as well as to about 9 percent of lung cancers, ACS researchers have reported.

Whole grains: Not eating enough whole grains can also increase your cancer risk. On the other hand, eating whole grains such as brown rice, whole wheat bread, and oatmeal may help prevent certain types of cancer. These grains are essential sources of dietary fiber, which could help prevent against colon cancer. A low-fiber diet is associated with roughly 10 percent of all colon cancer cases, according to ACS researchers. Heart-healthy whole grains also contain a variety of other compounds that could help prevent cancer.

Legumes: Like whole grains, legumes (beans) are another plant source that’s rich in cancer-fighting fiber. Beans are also good sources of folate. Include foods like kidney beans or black beans, lentils, and peas in your diet.

Dairy: “There’s a lot of mixed research with dairy, though with some cancers, it’s now looking like dairy may have a protective effect,” says Rashid. This appears especially true when it comes to preventing colon cancer. A low-calcium diet is tied to nearly 5 percent of all cases of the disease, the ACS says.

Experts suggest that you choose low-fat or fat-free dairy options.

Fermented dairy products often also 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 may help to be aware of which ones to emphasize and which ones to reserve as an occasional treat. It all 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.”

Article sources open article sources

Elizabeth Mendes. More than 4 in 10 Cancers and Cancer Deaths Linked to Modifiable Risk Factors. American Cancer Society. November 21, 2017.
Zhang FF, Cudhea F, Shan Z, et al. Preventable Cancer Burden Associated With Poor Diet in the United States. JNCI Cancer Spectr. 2019;3(2):pkz034. Published 2019 May 22.
Shawna Hite and Dan Remley. Processed Meats, Red Meats and Colorectal Cancer Risk. Ohio State University Extension Ohioline.
Aykan NF. Red Meat and Colorectal Cancer. Oncol Rev. 2015;9(1):288. Published 2015 Dec 28. doi:10.4081/oncol.2015.288
Fiolet T, Srour B, Sellem L, et al. Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort. BMJ. 2018;360:k322. Published 2018 Feb 14.
American Institute for Cancer Research. Recommendation: Limit Consumption of Red and Processed Meat. Accessed March 1, 2022.
American Institute for Cancer Research. Five Steps for Cancer-Safe Grilling. June 26, 2018.
GBD 2016 Alcohol Collaborators. Alcohol use and burden for 195 countries and territories, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016 [published correction appears in Lancet. 2018 Sep 29;392(10153):1116] [published correction appears in Lancet. 2019 Jun 22;393(10190):e44]. Lancet. 2018;392(10152):1015-1035.
National Cancer Institute. Alcohol Tied to 750,000 Cancer Cases Worldwide in 2020. August 12, 2021.
National Cancer Institute. Obesity and Cancer. Reviewed January 17, 2017.
National Cancer Institute. Chemicals in Meat Cooked at High Temperatures and Cancer Risk.  Reviewed July 11, 2017.
Halsted CH, Villanueva JA, Devlin AM, Chandler CJ. Metabolic interactions of alcohol and folate. J Nutr. 2002;132(8 Suppl):2367S-2372S. doi:10.1093/jn/132.8.2367S
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Rodríguez-Molinero J, Migueláñez-Medrán BDC, Puente-Gutiérrez C, et al. Association between Oral Cancer and Diet: An Update. Nutrients. 2021;13(4):1299. Published 2021 Apr 15. doi:10.3390/nu13041299
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