Ultraprocessed Foods: Science Facts and Shopping Tips 

You might have heard the buzz about ultraprocessed foods being unhealthy. But what are they, exactly? And are they really all that bad? 

A lot of familiar and, frankly, favorite foods fall into the ultraprocessed food category, so it’s good to get the facts about the risks and expert tips for making your shopping cart healthier.  

At Dana-Farber, our experts are looking at ultraprocessed foods and their association with cancer risks from multiple angles.  

• Dana-Farber experts in colorectal cancer have studied the effects of processed meats on colon health. They’ve uncovered the biological mechanisms that link some of these foods to an increased risk of colon cancer.  
• Dana-Farber experts in nutrition have helpful tips for how to take these scientific discoveries about ultraprocessed foods and use them to your advantage on your next run to the food store. 

What are ultraprocessed foods? 

Dana-Farber nutritionist Annette M. Goldberg, MBS, MS, RD, says all foods fall into four categories, based on the United Nations NOVA system that classifies foods based on the amount of processing they’ve gone through.  

• Unprocessed foods like fresh fruits, vegetables, poultry, and fish. 
• Processed culinary ingredients like butter, oil, salt, and sugar. 
• Processed foods that blend the first two categories, such as bread, jam, cheese, or nut butter. 
• Ultraprocessed foods that contain additives such as dyes, added flavors, non-sugar sweeteners, and ingredients that change the texture or appearance of a food. This could include sodas, certain plant-based meat substitutes, and sweetened breakfast cereals. 

“Not every type of processed food is necessarily bad for health,” says Goldberg. “Look for food that has a limited amount of disruption to the food and its nutritional content.” 

For example, canned vegetables, frozen fruit, and ground chicken are all lightly processed foods but have retained their nutritional value. 

What are the links between ultraprocessed foods and cancer? 

There are three ways that ultraprocessed foods are linked to an increased cancer risk. 

1. Processed meats, red meat, and DNA damage. Many studies have linked the consumption of red meat and processed meats, such as hot dogs, bacon, and deli meats, to an increased risk of colon cancer. In a novel study of the effects of processed meats on colorectal cancer in patients, Dana-Farber’s Marios Giannakis, MD, PhD, and colleagues found that a high intake of red and processed meat, which contain compounds such as nitrates, can leave a “signature” of DNA damage in cells of the colon.  

Giannakis and colleagues are performing follow-up studies of the effects of red meat and its compounds on models of tumors. This work will enable them to learn more about what is happening in these cells and who may be the most susceptible individuals. “We hope to learn more so we can make more precise recommendations,” says Giannakis, a gastrointestinal cancer physician and researcher. “But for now, I would advise moderation of red meat consumption.” 

The American Institute for Cancer Research (AICR) recommends no more than 12 to 18 ounces (three 4 to 6-ounce servings) of red meat (beef, pork, and lamb) per week and avoiding processed meat. 

2. Junk food and obesity. Ultraprocessed foods often diminish or eliminate the nutritional value of a food. This turns them into “junk” foods that might contribute to weight gain. Excessive weight gain and obesity are risk factors for cancer. Stored adipose tissue produces hormones and inflammatory factors, both of which can fuel cancers. Excess weight is linked to 13 different cancers, including breast, esophageal, pancreatic, colon, ovarian, prostate, and gastric cancers.  

“We used to think that adipose tissue wasn’t active, that it was just stored energy,” says Goldberg. “But now we know it is metabolically active and, in excess, can be damaging.” 

3. The unknown. It isn’t clear yet how additives in or packaging of ultraprocessed foods might affect cancer risk. Studies suggest that ultraprocessed foods are broadly linked to an increased risk of many types of cancer, but more research is needed to determine what these foods might be doing in the body to increase the risk of cancer.  

There are several hypotheses, says Giannakis. For instance, ultraprocessed foods might: 

• Directly damage normal cells. 
• Contain substances that lead to persistent inflammation.  
• Modify the immune system in ways that interfere with surveillance against cancers. 
• Contribute to a change in the microbiome, the bacteria in the gut, that could result in ill effects. 

“It’s a complex question and the mechanisms that might link ultraprocessed foods to cancer have not been firmly established for many of these factors,” says Giannakis.  

Should I avoid ultraprocessed foods altogether? 

Goldberg recommends that people focus on including more healthy foods in their diet. Her tips include: 

• Rebalance your plate. Create a healthy plate by filling three-quarters of your plate with plant-based whole foods. Leave the rest for the protein, which can include beans, tofu, poultry, fish or, on occasion, red meat. 
• Prioritize fresh foods: Include a variety of raw vegetables, fruits, seafood, poultry, eggs, and dairy. 
• Shop the frozen and canned foods aisles. If fresh fruits and vegetables are hard for you to find or keep, consider frozen fruits and vegetables, canned beans, canned tomatoes, and whole grains. “Beans and grains can be inexpensive and shelf stable,” she says.  
• Try to live by the 80-20 rule (or better, 90-10). Limit your intake of ultraprocessed foods to just 10 or 20% of the time. This is easier to achieve if you cook at home more often. “But, if you’re going to a birthday party, go ahead and have a piece of cake,” says Goldberg.  

The AICR also has many tips for eating a healthy diet.  

Are some ultraprocessed foods better than others? 

Not all ultraprocessed foods are alike. And not every person is the same. We all have different priorities, goals, and concerns. For instance, if you currently have cancer, are a cancer survivor, or if you have another medical condition, work with your provider and follow their dietary recommendations.  

Learn more about nutrition services for patients with or recovering from cancer at Dana-Farber.  

In general, there are a few basic rules of thumb that can help with decision-making at the food store. 

1. Avoid processed meats and keep red meat (beef, pork, and lamb) to two servings per week. 
2. Avoid common ultraprocessed foods like flavored or sweetened white rice, sweetened breakfast cereal, potato chips, soda, and frozen fried chicken. 
3. Try to maintain a healthy weight by avoiding foods that are high in calories and have low nutritional value. 
4. Read the label and avoid foods with added nitrites or nitrates, and foods that are cured or salted. Ask yourself if you can read and understand the ingredient list. The shorter the list, the better.  

Goldberg notes that there are online tools, such as Yuka or Open Food Facts, that can give you an idea of why you might want to avoid a certain ultraprocessed food and can recommend alternatives to consider. These types of tools can help with decisions, but the decisions aren’t always straightforward. 

“You want to apply a bit of common sense,” says Goldberg. “These tools can give you some good information to consider, and then you can make your own decision based on your own personal concerns, be that related to calories, or salt intake, or something else.”