Researchers find certain foods might increase colorectal cancer risk.
Highly processed foods have become a regular part of the American diet, accounting for more than half of the calories consumed by U.S. adults. These products include a wide range of items, from hot dogs and packaged snacks to whole-wheat bread and breakfast cereal. Because foods with very different ingredients and nutritional qualities fall into this same category, researchers have questioned whether the level of processing alone tells the full story about potential health risks. A new study suggests that the types of foods people eat may matter more than their overall intake of ultra-processed products when it comes to the connection between poor dietary habits and colorectal (colon) cancer.
Published in PLOS Medicine, the research examined whether consumption of ultra-processed foods was associated with colorectal cancer among hundreds of thousands of American adults. Researchers found no connection between the total amount of ultra-processed food participants consumed and their likelihood of developing the disease. However, when they examined individual food categories, different patterns emerged. Whole grains and dairy products from ultra-processed sources were associated with lower risk, while meat from those sources was associated with higher risk.
The research included 461,682 adults enrolled in the National Institutes of Health-AARP Diet and Health Study. Participants were between 50 and 71 years old and did not have cancer when they joined the project in 1995 or 1996. At enrollment, they completed a food questionnaire containing 124 items. Researchers used the Nova classification system to group foods according to their level of processing. Ultra-processed products accounted for a median of 43% of participants’ daily calorie intake. Participants were followed through 2018, with an average follow-up period of 18.8 years. During that time, 10,075 people received a colorectal cancer diagnosis. Researchers considered several factors that could affect the findings, including age, sex, race and ethnicity, education, physical activity, smoking habits and alcohol consumption.
When comparing participants with the highest and lowest levels of ultra-processed food consumption, researchers did not find a higher overall colorectal cancer risk among those eating more of these products. The results changed when specific food groups were considered. Each additional daily serving of whole grains from ultra-processed sources was associated with a 13% lower risk. Fiber intake was also associated with lower risk.
Dairy products showed a similar pattern. Each additional daily serving of dairy from ultra-processed sources was associated with a 25% lower colorectal cancer risk. Dairy from other sources was associated with a 10% lower risk. Researchers also found that higher calcium intake was associated with lower risk, although the study could not determine whether calcium from nondairy foods offered the same potential benefit.
Meat showed a different relationship. Each additional daily serving of meat from ultra-processed sources was associated with an 8% higher risk of colorectal cancer. Meat from other sources was associated with a 4% higher risk. Reconstituted meat and fish products were also linked to higher risk. Researchers wrote that many of the foods in these categories were already part of participants’ diets. Approximately 83% of whole grains and 74% of processed meat consumed by the study group came from ultra-processed products.
The findings do not mean that there is a direct one-to-one connection between all ultra-processed foods and colorectal cancer. Instead, the research suggests that the nutritional content of foods may play an important role in understanding how eating habits relate to cancer risk. More research is needed to clarify these relationships and determine how specific ingredients and food choices affect an individual’s long-term health.
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Scientists just connected 2 types of ultra-processed foods to lower colon cancer risk
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