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

The ease of pre-cooked and instant meals may make it simple for many Americans to overlook the less-than-ideal nutritional information, but after finding a connection between the frequent consumption of ultra-processed foods and an elevated risk of colorectal cancer, a group of researchers led by those at Tufts University and Harvard University hope that will change.

According to a study that was released on August 31 in The BMJ, men who consumed a lot of ultra-processed foods had a 29% higher risk of getting colorectal cancer, which is the third most common cancer diagnosed in the country, than those who consumed far less of it. In women, they did not discover the similar relationship.

Lu Wang, a postdoctoral scholar at the Friedman School of Nutrition Science and Policy at Tufts University and the study's principal author, said, "We initially thought that colorectal cancer could be the cancer most impacted by food compared to other cancer types." "The majority of ultra-processed foods, including processed meats, increase the risk of colorectal cancer. Added sugars and a lack of fiber in ultra-processed meals both lead to weight gain and obesity, which is a recognized risk factor for colorectal cancer.

Over 200,000 participants' responses were reviewed, including 159,907 women and 46,341 men from three sizable prospective studies that evaluated dietary intake over a period of more than 25 years. Every four years, a food frequency questionnaire was given to each participant, asking about how frequently they ate 130 different items.

Participants' intake of ultra-processed foods was then divided into quintiles for the BMJ study, with values ranging from the least to the most. The highest quintile of people were found to have the greatest chance of getting colorectal cancer. Although a strong association between men's intake of ultra-processed foods and colorectal cancer was seen, particularly in cases of the disease in the distal colon, the study did not reveal an overall elevated risk for women.

The research showed that there are disparities between how men and women consume ultra-processed meals and the potential cancer risk that goes along with it. The research team identified 1,294 male cases of colorectal cancer among the 206,000 patients who were tracked for more than 25 years and 1,922 female cases.

The researchers discovered that among men, ready-to-eat items containing meat, poultry, or fish have the highest link to colorectal cancer. Some processed meats including sausages, bacon, ham, and fish cakes are among these goods. This supports our theory, according to Wang.

Additionally, the group discovered that males who consume more sugar-sweetened beverages such soda, fruit-based drinks, and sugary milk-based beverages have a higher chance of developing colorectal cancer.

However, not all ultra-processed meals pose the same risk of developing colon cancer. We discovered a negative relationship between the risk of colorectal cancer in women and ultra-processed dairy products like yogurt, according to co-senior author Fang Fang Zhang, a cancer epidemiologist and acting chair of the Friedman School's Division of Nutrition Epidemiology and Data Science.

Overall, there was no association between eating ultra-processed food and a woman's chance of developing colorectal cancer. It's probable that women's consumption of ultra-processed meals has a different nutritional profile than men's.

According to Zhang, yogurt may be able to mitigate the negative effects of other ultra-processed food kinds on women.

"Further research will need to determine whether there is a true sex difference in the associations, or if null findings in women in this study were simply due to chance or some other uncontrolled confounding factors in women that mitigated the association," added 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.

Although ultra-processed meals are frequently linked to poor diet quality, there may be other factors that influence the risk of getting colorectal cancer in addition to the ultra-processed foods' poor diet quality.

Zhang observed that a number of factors may contribute to the development of cancer, including the possible impact of food additives on gut flora, the promotion of inflammation, and pollutants created during food processing or emitted from food packaging.

The study team had a lot of information to examine and evaluate because each of the three investigations had more than 90% follow-up rates.

In our epidemiological investigations, we have demonstrated the potential latency effect, which means that it may take years before a particular exposure has an impact on the chance of developing cancer, according to Song. It's crucial to have long-term exposure to data to better assess cancer risk because of this drawn-out process.

121,700 licensed female nurses between the ages of 30 and 55 participated in The Nurses' Health Study between 1986 and 2014.

There were 116,429 female nurses in the Nurses' Health Study II (1991–2015) between the ages of 25 and 42.

51,529 male health professionals between the ages of 40 and 75 participated in the Health Professional Follow-up Study (1986–2014).

The researchers were left with prospective data from 159,907 women from both NHS groups and 46,341 males after an exclusionary process for past illnesses or incomplete surveys.

The researchers controlled for variables that could have affected the results, including race, family history of cancer, endoscopic history, physical activity hours per week, smoking status, total alcohol and calorie intake, aspirin use on a regular basis, and menopausal status.

Zhang is aware that the results for this cohort might differ from those for the general population since the study participants may be more inclined to eat healthily and steer clear of highly processed foods because they all worked in the healthcare industry. Due to changes in processing during the past 20 years, the statistics may also be skewed.

However, Zhang emphasized, "We are comparing within that demographic those who eat bigger amounts vs lower amounts." Therefore, the comparisons are accurate.

In a prior study, Wang and Zhang found that children and adolescents in the United States were increasingly consuming foods that had undergone extreme processing. Both results support the premise that many diverse populations may rely on highly processed foods as part of their daily diets.

According to Zhang, who is also a member of the Tufts Institute for Global Obesity Research, "Much of the dependence on these meals can come down to variables like food access and convenience." "Foods can help extend their shelf lives by being chemically processed, however many processed foods are less healthful than their raw counterparts. We must educate people about the dangers of regularly consuming unhealthy meals and make it simpler for them to select better alternatives.                                                                                                 

Wang hopes that this study—among others—will help bring about changes in dietary restrictions and recommendations, but she is aware that change won't come quickly.

Wang continued, "Long-term reform will require a multi-step approach." Researchers are still investigating how dietary guidelines, recipe and formula adjustments, and regulations relating to nutrition might enhance general health and lessen the burden of cancer. We must keep researching the connection between nutrition and cancer, as well as potential remedies to ameliorate the situation.

Tufts University, Health Sciences Campus