Ultra-processed food consumption linked to risk for colorectal cancer among men
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Key takeaways:
- Men in the highest quintile of ultra-processed food consumption had a 29% higher risk for developing colorectal cancer.
- Researchers observed no association of overall ultra-processed food consumption and increased colorectal cancer risk among women.
- Consumption of ultra-processed dairy foods, including yogurt, appeared associated with lower colorectal cancer risk among women.
High overall consumption of ultra-processed food appeared associated with a higher risk for colorectal cancer among men, but not women, according to study results published in The BMJ.
The findings also showed an association between consumption of ultra-processed dairy foods, including yogurt, and lower colorectal cancer risk among women.
Methods
Previous research has shown an association between ultra-processed food consumption and higher risks for obesity, high blood pressure, cholesterol and some cancers, but few studies have assessed the association between ultra-processed food intake and colorectal cancer risk, Fang Fang Zhang, MD, PhD, Neely Family professor and associate professor at Friedman School of Nutrition Science and Policy at Tufts University, told Healio.
“The dietary risk factors for colorectal cancer include high consumption of red and processed meats and low consumption of dietary fiber and whole grains,” Zhang said. “Ultra-processed foods, including processed meats, are low in dietary fiber, are also energy dense and contain a high level of added sugars, which contributes to obesity, a known risk factor for colorectal cancer. This is what motivated us to study the association between ultra-processed food consumption and colorectal cancer risk in the U.S. adult population.”
The study included 46,341 men from the Health Professionals Follow-up Study and 159,907 women from the Nurses’ Health Study (n = 67,425) and the Nurses’ Health Study II (n = 92,482) with valid dietary intake measurement and no cancer diagnosis at baseline.
Researchers used food frequency questionnaires to assess dietary intake every 4 years.
“We conducted this research among more than 200,000 U.S. adults who had been followed for between 24 and 28 years,” Zhang said. “Because cancer takes years and decades to develop, it is critical to have long-term exposure to evaluate true cancer risk.”
The estimated association between ultra-processed food consumption and risk for colorectal cancer with the use of time-varying Cox proportional hazards regression models adjusted for potential confounding factors served as the main outcome.
Findings
Researchers identified 3,216 colorectal cancer cases (women, n = 1,922; men, n = 1,294) during the study period.
Results showed men in the highest fifth of ultra-processed food consumption had a 29% higher colorectal cancer risk compared with those in the lowest fifth of consumption (HR = 1.29; 95% CI, 1.08-1.53). Of note, researchers found the positive association to be limited to distal colon cancer, with a 72% increased risk (HR = 1.72; 95% CI, 1.24-2.37). After the researchers adjusted for BMI or indicators of nutritional quality of the diet, such as Western dietary pattern or dietary quality score, the associations remained significant.
However, researchers found no association between overall consumption of ultra-processed food and colorectal cancer risk among women.
An analysis of ultra-processed food subgroups showed men with a higher consumption of meat-, poultry- and seafood-based ready-to-eat products (HR = 1.44; 95% CI, 1.2-1.73), including hot dogs, salami, bologna, sausages and sugar-sweetened beverages (HR = 1.21; 95% CI, 1.01-1.44), had a higher risk for colorectal cancer. Women with a higher consumption of ready-to-eat or heat mixed dishes, including pizza, had a higher risk (HR = 1.17; 95% CI, 1.01-1.36).
Of note, researchers found an association of higher consumption of ultra-processed dairy foods, including yogurt, with a lower colorectal cancer risk among women (HR = 0.83; 95% CI, 0.71-0.97).
Implications
Ultra-processed food consumption is common in the U.S., contributing to a large percentage of daily calories that Americans consume — 57% among adults and 67% in children, Zhang said.
“An increasing number of studies have reported a link between ultra-processed food consumption and adverse health outcomes, including an increased risk for some cancers,” she continued. “Colorectal cancer has the largest number of diet-associated cancer cases in the U.S. adult population.”
Nutrition policies are needed to encourage the substitution of ultra-processed food with unprocessed or minimally processed food at the population level, Zhang said.
“This should include subsidizing unprocessed or minimally processed foods to make them more affordable, making unprocessed or minimally processed foods more accessible in schools and workplaces, discouraging ultra-processed food consumption through labeling and nutrition education and, importantly, considering food processing as a dimension in federal dietary recommendations in addition to nutrients,” she said.
In a related editorial, Carlos A. Monteiro, MD, PhD, professor of nutrition, and Geoffrey Cannon, MA, of the Center for Epidemiological Studies in Health and Nutrition, both in the School of Public Health at University of Sao Paulo in Brazil, also emphasized the need for increased access to nourishing food that promotes health.
“The overall positive solution includes making supplies of fresh and minimally processed foods available, attractive and affordable,” they wrote. “And sustaining national initiatives to promote and support freshly prepared meals made with fresh and minimally processed foods, using small amounts of processed culinary ingredients and processed foods. Enacted, this will promote public health. It will also nourish families, society, economies and the environment.”
References:
- Monteiro CA, et al. Br Med J. 2022;doi:10.1136/bmj.o1972.
- Wang L, et al. Br Med J. 2022;doi:10.1136/ bmj-2021-068921.
For more information :
Fang Fang Zhang, MD, PhD, can be reached at fang_fang.zhang@tufts.edu.
Perspective
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Amanda Bode, RDN, LD
This study provides insight into long-term consequences of dietary patterns on a population of initially cancer-free individuals. The longitudinal design of these large cohort studies (Nurses’ Health Study II and Health Professionals Follow Up Study), provide us with data of self-reported food intake in relationship to developing colorectal cancer. The study reinforces the research showing dietary patterns including processed foods associated with an increased incidence of colorectal cancer.
For men especially, reducing ultra-processed foods may reduce colorectal cancer risk. In addition to processed meats and added sugars, this study points at sugary breakfast foods, packaged sweets and desserts, and fats/condiments and sauces as sources of ultra-processed foods that contributed to the high-risk dietary patterns.
It is not clear why the study has shown differences in risk and intake between men and women. Possible reasons why there may be a difference are under-reporting of ultra-processed foods, better choices within the range of ultra-processed foods or female hormone profiles that may be protective against colorectal cancer.
Why do ultra-processed foods have this relationship with colorectal cancer risk? Perhaps it is the lack of fruits, vegetables and whole grains that alters the microbiota leading to inflammation. Or is it that the additives and preservatives used in processed foods result in damage to the gut? Further research using biological sampling methods may be able to give us insight.
My recommendations to patients who are seeking to reduce the risk for colorectal cancer continue to be to eat more whole grains, fruits, vegetables and lean proteins, as well as to avoid processed meats, foods using preservatives and added sugar as much as possible.
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