Thirty-two reasons to avoid ultra-processed foods

Hundreds of studies have tied higher intakes of ultra-processed foods to an increased risk of chronic diseases including obesity, heart disease, type 2 diabetes, fatty liver disease and colon cancer.

Eating too much ultra-processed food has also been associated with early death, especially cardiovascular-disease-related death.

Now, a new evidence review – the largest one conducted to date – has linked these industrial foods to 32 harmful health effects. Here’s what to know.

What are ultra-processed foods (UPFs)?

UPFs are industrial formulations made from chemically modified substances extracted from whole foods, along with additives to enhance taste, texture, appearance and shelf-life. They contain little, if any, whole food.

UPFs comprise of a broad range of ready-to-eat products including soft drinks, packaged snacks, mass-produced breads, muffins, pastries and cookies, protein bars, ice cream, processed meats, frozen foods and meals (e.g., French fries, pizza, chicken nuggets), margarine and many more.

According to an editorial that accompanied the study, “no reason exists to believe that humans can fully adapt to these products”.

Studies indicate a global shift toward an increasingly ultra-processed diet. In Canada, it’s estimated that nearly 50 per cent of the calories in our diet come from UPFs, with Canadian kids consuming even more.

The new research findings

The comprehensive evidence review, involving nearly 10 million people, was published on Feb. 28 in the journal BMJ. It was conducted by researchers from Johns Hopkins Bloomberg School of Public Health in the U.S., the University of Sydney and Sorbonne University in France.

The team analyzed 45 meta-analyses, published over the past three years, and found direct associations between consumption of UPFs and 32 adverse health outcomes. (A meta-analysis combines the findings from many studies to summarize the results.)

Adverse health outcomes included early death, colorectal cancer, pancreatic cancer, heart disease, hypertension, type 2 diabetes, abdominal obesity, overweight, inflammatory bowel disease, fatty liver disease, anxiety, depression, asthma and wheezing.

Overall, the findings suggested that diets high in UPFs may be “harmful to most – perhaps all – body systems”.

When the researchers graded the quality of the evidence, they found “convincing” evidence that a higher intake of UPFs was tied to an increased the risk of developing cardiovascular disease, dying from cardiovascular disease, type 2 diabetes and anxiety.

The evidence was “highly suggestive” that a greater intake of UPFs was associated with an increased likelihood of obesity, depression, sleep-related problems and dying from heart disease.

Ways UPFs may harm health

The researchers acknowledged that more research is needed to understand the ways in which ultra-processed diets are linked to poor health.

The available evidence indicates there are several aspect of UPFs, likely acting in combination, that may cause unfavourable health effects.

Compared to whole foods, UPFs have poorer nutritional profiles. During heavy processing, foods are stripped of nutrients, fibre and protective phytochemicals. UPFs are also typically high in added sugar, sodium and unhealthy fats.

As well, a diet heavy in UPFs displaces nutritious, whole and minimally-processed foods.

UPFs are also engineered in ways that drive excess consumption. For example, they contain added flavours and sweeteners that enhance palatability.

Industrial processing also changes the structure and texture of UPFs, making them “soft”, which speeds up chewing time and delays satiety.

And it’s thought that certain additives, such as artificial sweeteners and emulsifiers, can alter the composition of the gut microbiome in a direction that promotes inflammation.

Limitations, takeaways

The many studies included in the evidence review were observational and, unlike randomized controlled trials, don’t prove that eating lots of UPFs causes ill health.

Yet, it’s unethical to feed people lots of UPFs every day and wait to see which health effects show up years down the road.

According to Dr. Christopher van Tulleken, associate professor at University College London and author of Ultra-Processed People: Why We Can’t Stop Eating Food That Isn’t Food, “this study is entirely consistent with a now enormous number of independent studies which clearly link a diet high in UPFs to multiple damaging effects.”

The new findings also underscore the need for public health policies aimed at targeting and reducing consumers’ intake of UPFs.

Dr. van Tulleken, who was not involved with the study, maintains there is “far more evidence about this category of food than we normally need to motivate public health campaigns.”

Public polices include national dietary guidelines that recommend avoidance of UPFs, front-of-package labels that identify UPFs (mandatory in Canada as of Jan. 1, 2026), restricting advertising of UPFs to children and banning sales of these foods in or near schools and hospitals.

In the study’s accompanying editorial, the authors call on the United Nations to develop and implement a framework to regulate UPFs similar to that used to control tobacco.

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD