Many Americans may find it easy to ignore the less-than-ideal nutritional information on pre-cooked and instant meals because they are so convenient.

A team of researchers from Tufts University and Harvard University hopes that will change now as they have found a link between eating a lot of ultra-processed foods and having a higher risk of colorectal cancer.

Researchers found that men who consumed high amounts of ultra-processed foods had a 29 percent increased risk of developing colorectal cancer, which is the third most diagnosed cancer in the United States, compared to men who consumed much smaller amounts of ultra-processed foods.

The findings of the study were published in The BMJ today.

But, women were not affected by this.

“Processed meats,” as explained by Lu Wang, the study’s lead author, “most of which fall into the category of ultra-processed foods, are a strong risk factor for colorectal cancer. 

“Ultra-processed foods are also high in added sugars and low in fiber, which contribute to weight gain and obesity, and obesity is an established risk factor for colorectal cancer.”

Over 200,000 participants’ responses—159,907 women and 46,341 men—from three sizable prospective studies that evaluated dietary intake over a 25-year period were reviewed. 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 was found to have the greatest risk 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.

Effects of Highly Processed Foods

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 as 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. 

According to co-senior author Fang Fang Zhang, they “found an inverse association between ultra-processed dairy foods like yogurt and colorectal cancer risk among women.”

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 types 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 due simply to chance or some other uncontrolled confounding factors in women that mitigated the association,” added Mingyang Song, co-senior author.

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.

Reviewing the Data

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.

“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,” Song added. “Because of this lengthy process, it’s important to have long-term exposure to data to better evaluate cancer risk.”

The research included:

• 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 team took into account possible confounding factors like race, family history of cancer, history of endoscopy, hours of physical activity per week, smoking status, total alcohol intake and total caloric intake, regular aspirin use, and menopausal status.

Zhang knows that because all of the people who took part in these studies worked in health care, the results may not be the same as they would be for the general population, since the people in these studies may be more likely to eat healthy foods and avoid highly processed foods. Due to changes in processing during the past 20 years, the statistics may also be skewed.

However, Zhang emphasized, “we are comparing within that population those who consume higher amounts versus lower amounts. So those comparisons are valid.”

Changing Eating Habits

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 back up the theory that many diverse populations may rely on highly processed foods as part of their daily diets.

“Much of the dependence on these foods,” according to Zhang, “can come down to factors like food access and convenience.

“Chemically processing foods can aid in extending shelf life, but many processed foods are less healthy than unprocessed alternatives. We need to make consumers aware of the risks associated with consuming unhealthy foods in quantity and make the healthier options easier to choose instead.”

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 change 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 need further research into the possible interventions that could help people whose cancer has been linked to their diet.

Image Credit: Getty

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