Pre-cooked meals, processed meat and instant meals, with all of their convenience–and synthetic additives–have just taken another hit. Researchers in a new scientific study recently discovered a link between the high consumption of ultra-processed foods and an increased risk of colorectal cancer.
The study analyzed responses from over 200,000 participants—159,907 women and 46,341 men—across three large prospective studies which assessed dietary intake and were conducted over more than 25 years. Each participant was provided with a food frequency questionnaire every four years and asked about the frequency of consumption of roughly 130 foods.
For the study, participants’ intake of ultra-processed foods was then classified into quintiles, ranging in value from the lowest consumption to the highest. Those in the highest quintile were identified as being the most at risk for developing colorectal cancer. Although there was a clear link identified for men, particularly in cases of colorectal cancer in the distal colon, the study did not find an overall increased risk for women who consumed higher amounts of ultra-processed foods.
Analyzing the Long-term Data
“Cancer takes years or even decades to develop, and from our epidemiological studies, we have shown the potential latency effect—it takes years to see an effect for certain exposure on cancer risk. Because of this lengthy process, it’s important to have long-term exposure to data to better evaluate cancer risk.”
-Dr. Mingyang Song, co-senior author on the study and assistant professor of clinical epidemiology and nutrition at the Harvard T.H. Chan School of Public Health
With more than a 90% follow-up rate from each of the three studies, the research team had ample data to process and review…
The studies included:
- The Nurses’ Health Study (1986-2014): 121,700 registered female nurses between the ages of 30 and 55
- The Nurses’ Health Study II (1991-2015): 116,429 female nurses between the ages of 25 and 42
- The Health Professional Follow-up Study (1986-2014): 51,529 male health professionals between the ages of 40 and 75.
After an exclusionary process for past diagnoses or incomplete surveys, the researchers were left with prospective data from 159,907 women from both NHS studies and 46,341 men.
The team adjusted for potential confounding factors such as race, family history of cancer, history of endoscopy, physical activity hours per week, smoking status, total alcohol intake and total caloric intake, regular aspirin use, and menopausal status.
The researchers found that men who consumed high rates of ultra-processed foods were at 29% higher risk for developing colorectal cancer—the third most diagnosed cancer in the United States—than men who consumed much smaller amounts. They did not find the same association in women.
The analyses revealed differences in the ways that men and women consume ultra-processed foods and the prospective associated cancer risk. Out of the 206,000 participants followed for more than 25 years, the research team documented 1,294 cases of colorectal cancer among men, and 1,922 cases among women.
The team found the strongest association between colorectal cancer and ultra-processed foods among men come from the meat, poultry, or fish-based, ready-to-eat products.
The scientists also found higher consumption of sugar-sweetened beverages, like soda, fruit-based beverages, and sugary milk-based beverages, is associated with an increased risk of colorectal cancer in men.
Overall, there was not a link between ultra-processed food consumption and colorectal cancer risk among women. The researchers suspect this is because women eat different types of highly processed foods–like yogurt–that offer decreased risk of colon cancer.
What role do food additives play in cancer risk?
The scientists say that the potential role of food additives in altering gut microbiota, promoting inflammation, and contaminants formed during food processing or migrated from food packaging may all promote cancer development.
Journal reference: Wang, L., et al. Association of ultra-processed food consumption with colorectal cancer risk among men and women: results from three prospective US cohort studies, British medical Journal, August, 2022; 378. BMJ 2022;378:e068921. doi: https://doi.org/10.1136/bmj-2021-068921.