New study links ultra-processed foods to colorectal cancer in men

For many Americans, the convenience of ready and instant meals may make it easy to overlook less-than-ideal nutritional information, but a team led by researchers at Tufts University and Harvard University hopes that will change after a recent association between higher consumption of ultra-processed foods and an increased risk of colon cancer was discovered. and rectum.

In a study published on August 31 in BMJResearchers found that men who ate high levels of ultra-processed foods were 29% more likely to grow colorectal cancer— The third most diagnosed cancer In the United States – compared to men who consumed significantly less. They did not find the same association in women.

“We’re starting to think that colorectal cancer could be the cancer most affected by diet than other cancers,” said Lu Wang, lead author of the study and a postdoctoral fellow in the Friedman School of Nutrition Science and Policy at Tufts University. “Processed meat, most of which falls into the category of ultra-processed foods, is a strong risk factor for colorectal cancer. Ultra-processed foods are also high in added sugars and low in fiber, which contributes to weight gain and obesity, and obesity is a confirmed risk factor for colorectal cancer”.

The study analyzed the responses of more than 200,000 participants – 159,907 women and 46,341 men – across three large prospective studies that evaluated food intake It has been conducted for more than 25 years. Each participant was provided with a food frequency questionnaire every four years and asked about the frequency of consumption of approximately 130 foods.

to study in BMJThen, participants’ intake of ultra-processed foods was categorized into quintiles, ranging in value from lowest to highest consumption. The top quintile was identified as having the highest risk of developing colorectal cancer. Although a clear link was identified for men, particularly in cases of colorectal cancer in the distal colon, the study did not find an increased overall risk for women who ate higher amounts of ultra-processed foods.

Effects of ultra-processed foods

The analyzes revealed differences in the ways men and women consume ultra-processed foods and the potential risks associated with cancer. Of the 206,000 participants who were 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 that the strongest association between colorectal cancer and ultra-processed foods among men came from meat, poultry or fish-based ready-to-eat products. “These products include some processed meats such as sausages, bacon, pork and fish cakes. This is consistent with our hypothesis,” Wang said.

The team also found that higher consumption of sugar-sweetened beverages, such as soda, fruit-based beverages and sugary milk-containing beverages, was associated with an increased risk of colorectal cancer in men.

However, not all ultra-processed foods are equally harmful in terms of colon and rectal cancer risk. “We found an inverse association between ultra-processed dairy products such as yogurt and the risk of colorectal cancer among women,” said senior co-author Fang Fang Zhang, a cancer epidemiologist and interim chair of the Department of Epidemiology and Data Science at the Friedman School. .

Overall, there was no association between the consumption of ultra-processed foods and the risk of colorectal cancer among the women. The composition of ultra-processed foods that women consume may be different than that of men.

“Foods like yogurt can counteract the harmful effects of other types of ultra-processed foods in women,” Chang said.

Minjiang Song, study co-lead author and assistant professor of epidemiology and clinical nutrition at Harvard T.H. Chan School of Public Health, added that “Further research will need to determine whether there is a true gender difference in the associations, or whether the null results in The women in this study were only due to chance or some other uncontrolled confounding factor in the women that attenuated the association.

Although ultra-processed foods are often associated with poor diet quality, there may be factors beyond the poor diet quality of ultra-processed foods that influence the risk of colorectal cancer.

Zhang noted that the potential role of food additives in altering the gut microbiota, promoting inflammation, and contaminants formed during food processing or migrated from food packaging may all promote the development of cancer.

data analysis

With a more than 90% follow-up rate from each of the three studies, the research team had sufficient data for processing and review.

“Cancer takes years or even decades to develop, and from us Epidemiological studiesWe’ve shown the potential effect of latency — it takes years to see the effect of exposure to certain risks on cancer risk, Song said. “Because of this long process, it is important to have a long-term exposure to the data to better assess cancer risk.”

Studies included:

After an exclusion process for previous diagnoses or incomplete surveys, the researchers were left with prospective data from 159,907 women from both the NHS studies and 46,341 men.

The team adjusted for potential confounding factors such as race, family history of cancer, endoscopy history, hours of physical activity per week, smoking status, total alcohol intake and total calories, regular aspirin use, and menopausal status.

Zhang recognizes that because all participants in these studies all worked in health care, the results for this population might not be the same as they are for the general population, since participants may be more inclined to eat healthier and stay away from ultra-processed foods. The data may also be skewed because processing has changed over the past two decades.

“But we’re comparing these populations with those consuming higher versus lower,” Zhang reassured. “So these comparisons are valid.”

Changing dietary patterns

Wang and Zhang previously published a study set the direction in the increased consumption of ultra-processed foods in children and adolescents in the United States. Both studies confirm the idea that many different groups of people may rely on ultra-processed foods in their daily diets.

“The heavy reliance on these foods could be due to factors such as food access and convenience,” said Chang, who is also a member of the Tufts Institute for Global Obesity Research. “Chemical processing of foods can help extend the shelf life, but many processed foods are less healthy than unprocessed alternatives. We need to educate consumers about the risks associated with consuming unhealthy foods in large quantities and make healthier options easier to choose instead.”

Wang knows that change won’t happen overnight, and he hopes this study will contribute, among other things, to changes in dietary regulations and recommendations.

“Long-term change will require a multi-step approach,” Wang added. “Researchers continue to study how nutrition policies, dietary recommendations, and changes to recipes and formula, along with other healthy lifestyle habits, can improve overall health and reduce cancer burden. It will be important for us to continue to study the link between cancer and diet, as well as Potential interventions to improve outcomes”.