Scientists Just Connected 2 Types of Ultra-Processed Foods to Reduce Colon Cancer Risk

Ultra-processed foods account for more than half of the calories consumed by American adults. But the term “ultra-processed” includes everything from hot dogs to whole-wheat bread, which may explain why research linking these foods to colorectal cancer has been inconsistent. However, new research suggests that the contents of ultra-processed foods may have a greater impact on your risk of colon cancer than how they are processed.

Published in PLOS MedicineThe study found no link between total consumption of ultra-processed foods and colorectal cancer risk. However, whole grains and dairy products from ultra-processed sources were associated with lower risk, while consumption of meat from ultra-processed sources was associated with higher risk. Here’s what you need to know.

How was the study conducted?

Researchers analyzed 461,682 U.S. adults in the NIH-AARP Diet and Health Study. Participants were aged 50 to 71 and did not have cancer when they enrolled in 1995 or 1996. They completed a 124-item food frequency questionnaire, and researchers ranked each food using the Nova system, which sorts foods by degree of processing. Ultra-processed foods made up an average of 43% of participants’ daily calories.

Participants were followed until 2018, for a median of 18.8 years, during which time 10,075 people were diagnosed with colorectal cancer. The analysis was adjusted for factors including age, gender, race and ethnicity, education, physical activity, smoking and alcohol consumption.

What did the study reveal?

People in the top fifth of ultra-processed food consumption did not have a higher risk of colorectal cancer than those in the bottom fifth. However, this changed when researchers looked at the contents of these foods. Here is how the results broke down:

• Whole grains: Each additional daily serving from ultra-processed sources, such as bread and breakfast cereals, was associated with a 13% lower risk of colorectal cancer. Fiber consumption was also associated with lower risk.
• Milkman: Each additional daily serving was associated with a 25% lower risk of colorectal cancer when it came from ultra-processed sources and a 10% lower risk from other sources.
• Meat: Each additional daily serving from ultra-processed sources was associated with an 8% higher risk, plus a 4% higher risk from other sources. Reconstituted meat and fish products were also associated with higher risk.

Servings were measured per 1,000 calories consumed. About 83% of whole grains and 74% of processed meat in this cohort’s diet came from ultra-processed foods. Protective and harmful foods were therefore in the same category and perhaps compensated for each other. Poor overall diet quality was also associated with higher risk, regardless of the amount of ultra-processed foods consumed.

Boundaries

This is an observational study, so it cannot prove cause and effect. Diet was measured only once, and that was using a questionnaire that was not designed to assess food processing. The participants were older and mostly white, so the results may not apply to younger or more diverse groups, and the authors characterize the food group analyzes as exploratory. The researchers also did not evaluate food additives.

How does this apply to real life?

The study authors note that their findings are consistent with advice to eat more whole grains, fiber and dairy and avoid processed meat to prevent colorectal cancer.

Here are some helpful tips:

• Choose whole grains. Opt for breads and cereals whose first ingredient is a whole grain, such as oats or brown rice.
• Include dairy products. Milk and yogurt are easy options. The study linked higher calcium intake to a lower risk of colorectal cancer, but it can’t say whether non-dairy sources of calcium offer the same benefit, so ask a dietitian if you’re avoiding dairy.
• Substitute processed meat. Try beans, lentils, tofu or leftover roast chicken in place of red meats like cold cuts, hot dogs and bacon.

Our expert opinion

A study of more than 460,000 U.S. adults found no link between total consumption of ultra-processed foods and colorectal cancer risk, but it did find that ingredients in some processed foods may increase your risk. Whole grains and dairy products were associated with lower risk, while meat from ultra-processed sources was associated with higher risk. The takeaway is not that you should eat ultra-processed foods, but that you should be careful about what’s in the processed foods you eat. Try to eat more whole grains and dairy products and reduce your intake of processed meat.