Developing multiple health conditions, including cancer, linked to ultra-processed foods

Stock image of processed foods
Sugary and artificially-flavoured drinks and ultra-processed meats like hot dogs were significantly linked to the development of cancer and other disease. Photo credit: bit245 / iStockphoto / Getty Images

By Sandee LaMotte of CNN

Eating higher amounts of ultra-processed food raises the risk of being diagnosed with multimorbidity, or having multiple chronic conditions such as diabetes, heart disease and cancer, a new study found.

"What is particularly significant in this large study is that eating more ultra-processed foods, in particular animal products and sweetened beverages, was linked to an increased risk of developing cancer along with another disease such as a stroke or diabetes," said Helen Croker, assistant director of research and policy at World Cancer Research Fund International, which funded the study, in a statement.

However, the increased risk was modest, said Tom Sanders, professor emeritus of nutrition and dietetics at King's College London, who was not involved in the study. 

"This paper reports a 9 percent increase in risk of multimorbidity to be associated with higher intake of ultra-processed food," Sanders said in a statement.

"Food intake was measured by a questionnaire on one occasion a long time ago. This is important as dietary patterns have changed quite markedly in the past 25 years with more food eaten outside the home and more ready prepared food being purchased," Sanders said.

While the study cannot conclusively prove that ultra-processed foods are the direct cause of the multiple diseases, a good deal of other research has shown a connection between certain ultra-processed foods (UPF) and health harms, said nutrition researcher Ian Johnson, emeritus fellow at Quadram Institute Bioscience in Norwich, United Kingdom. He was not involved in the study.

"Taken with all the other scientific evidence it is very likely that some types of UPF do increase the risk of later disease, either because they are directly harmful or because they replace healthier foods such as vegetables, fruit, nuts, seeds, olive oils, etc," Johnson said in a statement. 

The study's findings are concerning because in Europe ultra-processed foods make up "more than half of our daily food intake," said co-author Heinz Freisling, a nutrition and metabolism scientist at the International Agency for Research on Cancer, in a statement. In the United States, a 2019 study estimated some 71 percent of the food supply may be ultra-processed.

Ultra-processed foods contain ingredients "never or rarely used in kitchens, or classes of additives whose function is to make the final product palatable or more appealing," according to the Food and Agriculture Organization of the United Nations.

The list of additives includes preservatives to resist mould and bacteria; emulsifiers to keep incompatible ingredients from separating; artificial colourings and dyes; anti-foaming, bulking, bleaching, gelling and glazing agents; and added or altered sugar, salt and fats designed to make food more appealing.

Not all ultra-processed foods were harmful 

The study, published Monday in the journal The Lancet, collected dietary information from 266,666 men and women from seven European countries between 1992 and 2000. Researchers followed the participants for 11 years to see who developed various chronic conditions, including cancer.

As they entered the study, each person was asked to recall what they typically ate over the last 12 months, and researchers categorized the foods by the NOVA classification system, which looks beyond nutrients to how foods are made.

"To estimate it researchers had to break down foods into different ingredients to try and work out if it is ultra-processed or not," said Duane Mellor, a registered dietitian and senior teaching fellow at Aston Medical School in Birmingham, United Kingdom. Mellor was not involved in the study.

"This approach, especially as the food data is up to 30 years old, could make this type of interpretation of historical data using a modern definition open to error," Mellor said in a statement. 

When ultra-processed foods were examined by subgroups, not all appeared to be associated with developing multiple chronic conditions, said lead author Reynalda Córdova, a postdoctoral student in pharmaceutical, nutritional and sport sciences at the University of Vienna.

"While certain groups, such as animal products and artificially and sugar-sweetened beverages, were associated with increased risk, other groups, such as ultra-processed breads and cereals or alternative plant-based products, showed no association with risk," Córdova said in a statement.

"Our study emphasizes that it is not necessary to completely avoid ultra-processed foods; rather, their consumption should be limited, and preference be given to fresh or minimally processed foods," co-author Freisling said in a statement.