‘Cocktail effect’ of ultra-processed foods linked to poor health
UPFs include ice cream, processed meats, crisps, mass-produced bread, some breakfast cereals, biscuits, many ready meals and fizzy drinks.
After recent debate over the scale of the effect ultra-processed foods (UPFs) actually have on our health, new evidence suggests a higher intake of UPFs could have a “cocktail effect” on our bodies.
Researchers reviewed the available evidence to date found links between UPFs and poor health, though one expert said studies on UPF and health are based on “very unreliable data”.
Previous research has shown that UPFs are linked to worse health.
There is debate over the scale of the effect and the extent to which processing itself is to blame compared with the fact many UPFs can cause health problems as they are high in fat, sugar and salt.
UPFs include ice cream, processed meats, crisps, mass-produced bread, some breakfast cereals, biscuits, many ready meals and fizzy drinks.
They also tend to include additives and ingredients that are not used when people cook from scratch – such as preservatives, emulsifiers and artificial colours and flavours.
More than half our food is UPFs
In the UK, around 56% of calories on average come from UPFs, rising to 68% in teenagers.
These figures are far higher than in comparable European countries such as France and Italy.
In the new review, published in the journal Family Medicine and Community Health, researchers found that every extra 100g of UPF consumed was linked to greater risks to health, such as developing high blood pressure and diabetes.
Experts examined 51 studies from the Americas, Europe, Asia, and Oceania, involving 8.8 million people tracked for two to 32 years.
UPF consumption was assessed by questionnaires asking how much people ate, dietary recall over the previous 24 hours, or a dietary history.
The results suggested that eating a lot of ultra processed foods was associated with higher risks of cardiovascular events such as heart attack (24%), cancer (12%), obesity/overweight (23%), metabolic syndrome/diabetes (24%), depression/anxiety (27%), digestive diseases (31%), high blood pressure (11%) and death from any cause (18%).
The more people ate, the greater the risks seemed to be.
"‘Cocktail effect’: a greater impact on human health than exposure to just a single additive.”
The team, including from the University of Singapore, said: “UPFs have lower nutritional value and high energy, which may increase eating rate and delay satiety signalling, leading to higher overall food intake and higher body weight.
“Additionally, emerging evidence suggests that the combination of multiple additives, such as artificial sweeteners, may have a potential ‘cocktail effect’, potentially having a greater impact on human health than exposure to a single additive.”
The team said laboratory research has found that the altered physical composition of UPFs may have implications for health by affecting key biological pathways such as gut microbiome, inflammation and insulin resistance.
Furthermore, several compounds may form during food processing, such as acrylamide, a chemical substance formed when starchy foods, such as potatoes and bread, are cooked at high temperatures. This has been linked to poor health.
Gunter Kuhnle, professor of nutrition and food science at University of Reading, said of the findings: “While these kinds of studies are meant to provide the highest level of evidence by pooling research, the results can only be as good as the underlying research – and this is the problem with this study.
“Measuring food intake is notoriously difficult, as people are often not very good at remembering what they ate. Estimating UPF intake from these data is even more difficult for several reasons.”
He said the definition of UPF “is ambiguous, especially for more complex foods” and most dietary assessment methods do not collect sufficient data to categorise foods reliably.
For example, artisan bread is not UPF, he said, while supermarket bought bread generally is, “but many assessment methods simply record ‘bread’.”
He said some foods that are UPF are already known to have an adverse effect on health, such as sugary drinks or processed meat.
“It is therefore not surprising that a dietary pattern that includes such foods will show adverse effects with health,” he said.
Prof Kuhnle’s is a former member of the UK Committee on Toxicity of Chemicals in Food, Consumer Products, and the Environment, a current member of the Advisory Committee on Novel Foods and Processes – which advises the Food Standards Agency, and director of the Chemical Analysis Facility at the University of Reading, which provides analytical services to academic and commercial clients and receives research funding.