Is there a Place for Processed Foods in a Diet to Reduce Cancer Risk?
February 16, 2022 | 8 minute read
Do processed foods fit into a diet to reduce cancer risk? You can find plenty of pithy statements about this question. But sound bites don’t always represent good science.
When it comes to how—or if—processed foods play a role in eating patterns to reduce cancer risk, let’s consider the evidence using three key questions:
> Which processed foods?
> What’s the alternative?
> For whom?
How Do You Define “Processed Food”? A Crucial Question
Almost all food is processed in some way, when you include cooking and chopping.
But when it comes to processed foods, the real debate is about commercially processed foods, specifically those that are more highly processed—often called “ultra-processed” foods.
A system often used in research studies differentiates between:
- Minimally processed foods contain no added fats, salt, sugar or other additives.
Examples: frozen vegetables, fruit or vegetable juice, dried fruit or mushrooms, shelled nuts.
- Processed foods have salt, sugar, fat or additional starch ingredients added to a minimally processed food.
Examples: canned vegetables, beans or olives in brine; salted nuts; canned fish; cheese.
- Ultra-processed foods are made with industrial equipment and ingredients that break down whole foods and combine them with other ingredients (often including ingredients not found in home kitchens). This processing results in foods with extended shelf life that are ready-to-eat or ready-to-heat. Some are “hyper-palatable” foods with fine-tuned combinations of sugar, fat and salt that trigger the brain’s reward system in ways that make you want to keep eating.
Examples: soft drinks, fruit “drinks” (maybe 10% fruit juice), candy, ice cream, chips, sausage, chicken or fish “nuggets,” energy bars, sugar-sweetened “fruit” yogurt, veggie burgers.
Does it seem like that category of ultra-processed foods covers a wide range of products? Yes, and that’s one of the reasons that making sense of research on ultra-processed foods and cancer risk gets complicated.
Research on Ultra-Processed Foods and Health
Weight: Greater consumption of ultra-processed food as a whole category is strongly associated with a greater likelihood of weight gain, increased waist size and greater risk of overweight and obesity. Much of this research involves cross-sectional studies, which can’t establish whether consuming more ultra-processed food actually led to weight gain. But the link is also seen in prospective studies that show changes in weight, waist and body mass index (BMI) over time. Compared to people who consume the least ultra-processed foods, those who consume the most are more likely to develop overweight or obesity, and if they already have overweight, to develop obesity.
Cancer and Heart Disease: Ultra-processed foods that increase development of obesity inherently increase risk of chronic diseases like heart disease and cancer that are promoted by obesity. These foods could also raise health risks independent of weight gain. For example, some may influence blood pressure, blood sugar spikes, insulin levels and the gut microbiome.
But after adjusting for weight, evidence from human studies is inconsistent regarding an association of ultra-processed food consumption and chronic disease. In part, it’s hard to separate the influence of ultra-processed foods themselves from the quality of the overall dietary pattern. And high consumption of ultra-processed foods may be linked with lifestyle and socioeconomic factors that are related to risk of cancer and other chronic diseases.
Nutrition: Ultra-processed foods are often low in nutrient density.
- Because of high levels of added sugars and fats, the same size portion of foods categorized as ultra-processed are usually higher in calories compared to less processed foods.
- Ultra-processed foods are the major sources of the excessive sodium and added sugars in today’s diet.
- In portions providing the same calories, many ultra-processed foods are lower in dietary fiber and provide fewer nutrients than less processed foods. (Although, due to fortification, they’re not always lower in all nutrients.)
Studies on the links between processed foods and health often compare people with the highest consumption to people with the lowest consumption. We can’t assume that those results necessarily apply to people in the middle.
Processed Foods in AICR’s Recommendations
For reduced cancer risk, the AICR Recommendation to limit processed foods specifically targets foods that promote weight gain. Analysis for AICR’s Third Expert Report identified strong evidence that foods high in added sugars, fat or refined grains promote weight gain when consumed frequently or in large portions.
- Switch from sugar-sweetened soft drinks, energy drinks and bottled tea to water and unsweetened tea or coffee.
- Snack on fruits, vegetables or nuts instead of cookies and chips.
- Round out a meal with fruits, salad, raw vegetables or soup instead of French fries. Or if you’re craving some fries, get the smallest available order (share it, if you can) and rely on lower-calorie options to satisfy your hunger.
Nuances Among “Processed Foods” Matter
As a dietitian trying to provide advice about healthy eating, I’m troubled by messaging that wraps up a wide range of foods under one umbrella term of processed foods. They’re not all the same.
Limit processed foods high in sodium. These are major factors in the high levels of sodium in the average American’s diet. Reducing sodium is an important strategy to cut the toll that high blood pressure is taking on Americans’ health.
- Switch from “seasoned” grain mixes to those you flavor with your own seasonings. For a nutrition double-win, choose a whole grain like brown rice, quinoa, farro or sorghum.
- Canned vegetables are super-convenient, so look for those that have no added salt. With lower salt content, plan to ramp up the amounts of herbs or spices to please your palate.
- Instead of bottled salad dressings and commercial dressing mixes, it’s easier than you may think—and delicious—to top a salad with a homemade dressing of oil and lemon juice or vinegar.
- Canned soup can send sodium soaring. If you don’t want to start from scratch, look for reduced-sodium options. You can dilute the sodium content even further by “stretching” the soup with extra vegetables and beans, and adding some water, low-sodium bouillon or no-salt-added canned tomatoes to the pot.
Don’t let processed foods with reduced fiber and nutrient content dominate your diet. You don’t need to completely give up refined grains (like Italian bread, enriched pasta and white rice) or juice. But when processing removes valuable nutrients or most of the fiber, choose the ones that you enjoy the most in moderation, and give less-processed foods the largest part of your plate.
Select the processed foods that can make healthy eating easier and more attainable for you. Identify your biggest barriers to a diet that reduces cancer risk. Is it including more nutrient-rich plant foods? Or reducing processed meat, excessive red meat and high-calorie snacks?
Healthy eating doesn’t mean including only perfect foods. It means choosing the foods and portions that help you create overall eating patterns that promote health and fit in your life.
- Add canned black beans, chickpeas, lentils and other pulses to soups, pasta or rice casseroles and salads. Look for options with no-salt-added. If not available, substantially reduce sodium by draining the beans into a strainer and rinsing with water.
- Canned tomatoes and plain pumpkin provide easily-absorbed carotenoid compounds and add flavor and texture to all kinds of mixed dishes. Choose canned tomatoes without added salt if you can find them, or at least leave out any of your own salt in cooking.
- Use tuna, clams, salmon and other seafood in cans or packets as an easy choice to help you cut back on processed meats or too much red meat. Especially for the ready-to-eat packets, try to choose those with the lowest sodium content.
Key Question: What is a Healthy Dietary Pattern?
AICR’s Third Expert Report concluded that a diet that reduces cancer risk is a diet rich in whole grains, vegetables, fruits and beans—eaten in portions that help maintain a healthy weight.
- If your diet is high in added sugars or foods that are very concentrated in calories even in limited portions, then cutting back on highly processed foods may be an important step.
- If your eating patterns are low in vegetables, fruits, whole grains and beans, then choose the forms that you can most realistically include as replacements for less nutritious foods you eat now.
Ground Your Choices in Evidence-Based Recommendations
Before you label a processed food as unhealthy, stop to consider what alternative choices are available for a particular individual or in a particular situation. For people with disabilities or recovering from illness, limited facilities or skills to prepare foods or limited ability to get to a grocery store, having a stock of processed foods on hand can be a positive—not negative—influence on diet quality.
The role of processed foods—and especially highly-processed foods—is a hot topic. It’s important, since surveys show that they now constitute the majority of foods in many Americans’ eating patterns. But don’t let headline hype and sound bites distract you from the overall picture of what research shows about how eating patterns can reduce cancer risk.