While the upcoming long weekend may call for celebrations, this time around, maybe rethink the hot dogs, soda, and prepackaged snacks. Two large-scale studies have linked overconsumption of “ultra-processed foods” to an increased risk of a number of diseases, including obesity, cancer, cardiovascular disease, early death, and more.
The authors define ultra-processed foods as “industrial formulations made entirely or primarily of substances derived from foods (oils, fats, sugar, starch and proteins), derived from food ingredients (hydrogenated fats and modified starches), or synthesized in laboratories from food substrates or other organic sources (flavor enhancers, colors and a few food additives used to make the product extra palatable).” This definition is based on the NOVA food classification system. The document, published on August 31 in The British Medical Journal (BMJ) included two studies, one conducted in the United States and one in Italy.
The statewide study looked at 200,000 people (59,907 women and 46,341 men) for up to 28 years. Each study participant filled out a questionnaire every four years, listing how often they ate about 130 different foods, ranging from unprocessed foods like fruit to ultra-processed ones like bacon. Long-term studies have found an association between ultra-processed foods and colorectal cancer in men but not in women. Men in the highest quintile of ultra-processed food consumption had a 29% higher risk of developing colorectal cancer than those in the lowest quintile. The results of the Italian study found similar dangers in ultra-processed foods.
The reasons for the gender differences are not yet clear.
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“We found an inverse association between ultra-processed dairy foods such as yogurt and the risk of colorectal cancer among women,” said co-senior author Fang Fang Zhang, a cancer epidemiologist and interim chair of the Division of Nutritional Epidemiology and Data Science at the Friedman School, in a press release . Colorectal cancer is the third most diagnosed cancer in the United States and is among the fastest growing cancers in people under the age of 50.
Mingyang Song, co-senior author of the study and assistant professor of clinical epidemiology and nutrition at the Harvard TH Chan School of Public Health, added that “Further research will be needed to determine whether there is a true gender difference in the associations, or if the null findings in women in this study are simply due to chance or some other uncontrolled confounders in women that moderate the relationship.
A large body of research has linked processed meats (bacon, salami, beef jerky, etc.) to a higher risk of bowel cancer in both men and women. The relationship remained even after accounting for factors such as diet quality and body mass index. This new study found that all types of ultra-processed foods, not just meats, play a role to some degree.
“We started out thinking that colorectal cancer might be the cancer most affected by diet compared to other cancers,” said Lu Wang, the study’s lead author and a postdoctoral fellow at the Friedman School of Food Science and Policy at Tufts. , in the press release. “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 contributes to weight gain and obesity, and obesity is an established risk factor for colorectal cancer.
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Researchers recommend replacing ultra-processed foods with unprocessed or minimally processed foods to reduce risk.
The Italian study began in 2005 and followed 22,000 people in the country’s Molise region. It is designed to assess risk factors for cancer, heart disease and brain disease. The research was also published in BMJ also compared the role of nutrient-poor foods (high in sugar and saturated or trans-fat) with ultra-processed foods in the development of early death and disease.
“Our results confirm that consumption of both nutrient-poor and ultra-processed foods individually increases the risk of mortality, particularly from cardiovascular disease,” said Marialaura Bonaccio, an epidemiologist in the Division of Epidemiology and Prevention at the IRCCS Neuromed of Pozzilli and lead author of the study, in a press release.
When the team compared the two types of food to find out which contributed the most, they found that ultra-processed foods were “paramount in determining mortality risk,” according to Bonaccio. “This suggests that the increased mortality risk is not directly (or exclusively) due to the poor nutritional quality of some foods, but rather to the fact that these foods are mostly over-processed.”