Ultra-Processed Food Linked with Cancer

A new large-scale study highlights another reason to stay away from ultra-processed food, or those industrial ready-to-eat or ready-to-heat formulations made of little or no whole foods: a significant association with colorectal cancer in men. Colorectal cancer is the third most commonly diagnosed malignancy among both men and women in the United States and the second leading cause of death from cancer worldwide.

The study, published in The BMJ, looked at the diets of 46,341 men and 159,907 women every four years for 24-28 years using food frequency questionnaires. The participants were from three US cohorts, and had no cancer diagnosis at baseline. The researchers found a significant association between ultra-processed food consumption and colorectal cancer in men. No association was observed between ultra-processed food consumption and risk of colorectal cancer among women.

There were 3,216 cases of colorectal cancer (1,294 men and 1,922 women) documented during the 24-28 years of follow-up. Compared with those in the lowest fifth of ultra-processed food consumption, men in the highest fifth of consumption had a 29% higher risk of developing colorectal cancer.

Among the types of ultra-processed foods, higher consumption of meat/poultry/seafood-based ready-to-eat products and sugar-sweetened beverages among men and ready-to-eat/heat mixed dishes among women was associated with increased risk of colorectal cancer; yogurt and dairy-based desserts were negatively associated with the risk of colorectal cancer among women.

Diet has been recognized as an important modifiable risk factor for colorectal cancer. Ultra-processed foods now contribute 57% of total daily calories consumed by American adults, which has been continuously increasing in the past two decades. These foods are usually high in added sugar, oils/fats, and refined starch, unfavorably altering gut microbiota composition and contributing to increased risk of weight gain and obesity, which is an established risk factor for colorectal cancer. Diets high in ultra-processed foods are also usually low in nutrients and bioactive compounds that are beneficial for the prevention of colorectal cancer, such as fiber, calcium, and vitamin D.

Beyond poor nutrition profiles, ultra-processed foods commonly contain food additives such as dietary emulsifiers and artificial sweeteners, some types of which have been suggested to increase the pro-inflammatory potential of the gut microbiome. Furthermore, potential carcinogens may also be formed during the processing of meats containing sodium nitrates, heat treatment, or may migrate from the packaging of ultra-processed foods (for example, bisphenol A).

These findings support the public health importance of limiting certain types of ultra-processed foods for better health outcomes.