Ultra-processed foods linked to heart cancer

For many Americans, the convenience of pre-cooked and instant meals may make it easy to overlook the less-than-ideal nutritional information, but a team led by researchers at Tufts University and Harvard University hope that will change after recently discovering a link between the high consumption of ultra-processed foods and an increased risk of colorectal cancer.

In a study published August 31 in The BMJ, 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.

“We started out thinking that colorectal cancer could be the cancer most impacted by diet compared to other cancer types,” said Lu Wang, the study’s lead author and a postdoctoral fellow at the Friedman School of Nutrition Science and Policy at Tufts. “Processed meats, 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.”

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 in BMJ, 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.

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. “These products include some processed meats like sausages, bacon, ham, and fish cakes. This is consistent with our hypothesis,” Wang said.

The team 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.

However, not all ultra-processed foods are equally harmful with regard to colorectal cancer risk. “We found an inverse association between ultra-processed dairy foods like yogurt and colorectal cancer risk among women,” said co-senior author Fang Fang Zhang, a cancer epidemiologist and interim chair of the Division of Nutrition Epidemiology and Data Science at the Friedman School.

Overall, there was not a link between ultra-processed food consumption and colorectal cancer risk among women. It’s possible that the composition of the ultra-processed foods consumed by women could be different than that from men.

Science Daily