In countries such as the UK, US and Canada, ultra-processed foods now account for 50 percent or more of calories consumed.
This is concerning, given that these foods have been linked to a number of different health conditions, including a greater risk of obesity and various chronic diseases such as cardiovascular disease and dementia.
Ultra-processed foods are concoctions of various industrial ingredients (such as emulsifiers, thickeners, and artificial flavors) amalgamated into food products by a series of manufacturing processes.
Sugary drinks and many breakfast cereals are ultra-processed foods, as are more recent innovations, such as so-called 'plant-based' burgers, which are typically made of protein isolates and other chemicals to make the products palatable.
The intense industrial processes used to produce ultra-processed foods destroy the natural structure of the food ingredients and strip away many beneficial nutrients such as fibre, vitamins, minerals, and phytochemicals.
Many of us are well aware that ultra-processed foods are harmful for our health. But it's been unclear if this is simply because these foods are of poor nutritional value.
Now, two new studies have shown that poor nutrition may not be enough to explain their health risks. This suggests that other factors may be needed to fully explain their health risks.
The role of inflammation
The first study, which looked at over 20,000 Italian adults, found that participants who consumed the highest number of ultra-processed foods had an increased risk of dying prematurely from any cause.
What's most interesting about these studies is that the health risks from eating a diet high in ultra-processed foods remained even after they had accounted for the poor nutritional quality of their diets. This suggests that other factors contribute to the harms caused by ultra-processed foods.
It also implies that getting the right nutrients elsewhere in the diet may not be enough to cancel out the risk of disease from consuming ultra-processed foods.
Similarly, attempts by the food industry to improve the nutritional value of ultra-processed foods by adding a few more vitamins may be side-stepping a more fundamental problem with these foods.
So what factors may explain why ultra-processed foods are so harmful to our health?
The Italian study found that inflammatory markers – such as a higher white blood cell count – were higher in groups that ate the most ultra-processed foods.
Our bodies may trigger an inflammatory response for any number of reasons – for example, if we catch a cold or get cut. The body responds by sending signals to our immune cells (such as white blood cells) to attack any invading pathogens (such as bacteria or viruses).
Usually, our inflammatory response resolves quite quickly, but some people may develop chronic inflammation throughout their body. This can cause tissue damage, and is involved in many chronic diseases – such as cancer and cardiovascular disease.
Many studies have found that poor diets can increase inflammation in the body, and that this is linked to higher risk of chronic diseases.
Given that signs of inflammation were seen in participants of the Italian study who ate the most ultra-processed foods, this could suggest that inflammation may contribute to why ultra-processed foods increase disease risk.
Some food additives common in ultra-processed foods (such as emulsifiers and artificial sweeteners) also increase inflammation in the gut by causing changes to the gut microbiome.
Some researchers have theorized that ultra-processed foods increase inflammation because they are recognized by the body as foreign – much like an invading bacteria. So the body mounts an inflammatory response, which has been dubbed 'fast food fever'. This increases inflammation throughout the body as a result.
Although the US colon cancer study did not establish if inflammation increased in the men consuming the most ultra-processed foods, inflammation is strongly linked with an increased risk of colon cancer.
Since inflammatory responses are hard-wired in our bodies, the best way to prevent this from happening is by not eating ultra-processed foods at all.
Some plant-based diets high in natural, unprocessed foods (such as the Mediterranean diet) have also been shown to be anti-inflammatory.
This may also explain why plant-based diets free from ultra-processed foods can help ward off chronic diseases. It's currently not known to what extent an anti-inflammatory diet can help counteract the effects of ultra-processed foods.
Simply reducing your intake of ultra-processed foods may be a challenge. Ultra-processed foods are designed to be hyper-palatable – and together with persuasive marketing, this can make resisting them an enormous challenge for some people.
These foods are also not labelled as such on food packaging. The best way to identify them is by looking at their ingredients. Typically, things such as emulsifiers, thickeners, protein isolates, and other industrial-sounding products are a sign it's an ultra-processed food.
But making meals from scratch using natural foods is the best way to avoid the harms of ultra-processed foods.