McMaster University study links ultra-processed food to range of health risks

New research out of McMaster University in Ontario has directly linked consumption of ultra-processed foods – a category that includes not just traditional junk foods, but items marketed as healthy as well – to several health issues.

The paper was written by McMaster University kinesiology researchers and published in the peer-reviewed journal Nutrition and Metabolism on Wednesday.

The researchers found that consumption of ultra-processed foods (UPFs) was linked with correlating levels of high blood pressure and cholesterol, and was not affected by an individual's age, size and level of activity.

Higher consumption of these processed foods is also linked to higher levels of triglycerides, "a type of fat found in the blood which, in high amounts, contributes to risk of heart disease, stroke and other diseases," study co-author and PhD student Angelina Baric told CBC Hamilton. 

She also said the research shows that processing foods changes how available the foods' nutrients are to the body and that higher consumption meant higher risk of health issues in every demographic researchers looked at.

Many links between the consumption of these foods and the cardiometabolic risk factors "remained significant even after adjusting for [Body Mass Index], suggesting that ultra-processed foods may influence health through mechanisms beyond weight gain, such as inflammation, insulin resistance, and poor metabolic regulation – all well-established predictors of heart disease and type 2 diabetes," McMaster said in a press release.

"The associations persisted even after adjusting for physical activity, smoking, the total amount of food consumed and socioeconomic factors including income and education," said the release.

What is ultra-processed food?

Ultra-processed foods are typically considered pre-packaged items that contain "ingredients you wouldn't use in home cooking, such as additives, emulsifiers, flavour enhancers and colours," Baric said. 

Examples include potato chips, hot dogs, deli meat and frozen foods. Baric said these foods often contain "substances that are extracted from whole foods rather than whole foods themselves."

They are often high in sodium, sugar and saturated fat, she added.

Even seemingly healthy foods such as protein bars and breakfast cereal largely fall under this category, Baric said.

Her team's research found that people with lower incomes were likely to eat more of these foods, but she says those of higher socioeconomic status might be more likely to consume processed foods targeted at the wellness and workout markets, such as protein powder, protein bars or energy drinks.

"Those are also ultra-processed," she said. "There's still a lot of additives added to these foods."

Making whole foods more accessible is key: report

The term "ultra-processed foods" is distinct from "processed foods," which typically refers to items with less than five ingredients, such as canned vegetables.

"Those might contain just oil, water, salt and peas," Baric said, noting canned tuna, some cheese and some types of bread also fall in this category.

Both of those terms stand in contrast with "whole foods," which are foods that arrive to the consumer in their natural state, such as vegetables, fruits, and animal products like meat or eggs.

Improving affordability of these foods is one of the key recommendations of the report.

"We found UPF intakes to be greatest amongst households with lower income and education," states the study, which also says men eat more UPFs than women.

"Targeted public health campaigns aimed at improving consumer awareness, particularly among these higher risk groups, standardized front-of-package labeling, restrictions on UPF marketing, and improving accessibility and affordability of more healthful, whole foods could help reduce UPF intake."

'Bodies are seeing these as non-foods'

McMaster calls the research a "landmark" study, saying it was the first in Canada to use "leverage population-based and robust biomarker data to examine this relationship."

The research team also includes Baric's PhD supervisor Anthea Christoforou, the paper's senior author, and Vasanti S. Malik, of the University of Toronto's Department of Nutritional Sciences.

They analyzed data from more than 6,000 adults across Canada, collected by Statistics Canada and Health Canada through the Canadian Health Measures Survey.

Baric said that this detailed data set includes a wide range of data such as height, weight and blood and urine test results, and is "a nationally representative sample of Canadians."

Christoforou said their results show that it's not just "the nutritional composition of a food" that matters to how healthy it is.

"It may be about the additives. The way the food is prepared. It's related to the packaging and the marketing of that food. All these things come together to create this food environment that really affects the healthfulness of our diets," she said in the McMaster release. 

She also noted that consumption of ultra-processed foods is linked to the presence of C-reactive protein, which the liver produces in response to inflammation, as well as an increase of white blood cells. 

"These two biomarkers indicate that these foods are causing an inflammatory response in our bodies," she said. "In a sense, this suggests that our bodies are seeing these as non-foods, as some kind of other element."