Common dietary advice encourages us to eat whole foods and avoid processed ones. But that is easier said than done given there is no clear understanding of what makes a food ultra-processed or how, if at all, these foods impact our health. Broadly labelling ultra-processed foods as bad could not only lead us to overlook other potential factors contributing to obesity, but may create a whole new set of unintended health consequences.
For decades, public health experts have raised alarms about ultra-processed foods, blaming them for global increases in obesity, diabetes and heart disease. Already, two countries 鈥� Canada and Brazil 鈥� have advice on avoiding ultra-processed foods in their national dietary guidelines. Many more countries, including the US and Australia, are debating whether to follow suit.
However, there are still too many unknowns about ultra-processed foods, including what they are and how they impact our health, to justify such sweeping recommendations, according to a panel of nutrition researchers discussing the topic at a in Boston on 23 July.
Advertisement
Despite the oft-repeated message that ultra-processed foods are bad for us, there is no universal definition of such products. The most widely used description is based on the system, developed by at the University of S茫o Paulo in Brazil. According to NOVA, a food is ultra-processed if it uses ingredients, often derived from other foods, to 鈥渋mitate or enhance the sensory qualities of foods or to disguise unpalatable aspects of the final product鈥�. Additionally, NOVA states that 鈥渁 multitude of sequences or processes is used to combine the usually many ingredients鈥� of ultra-processed foods, and these processes cannot be done at home.
This definition is broad and unclear, says at the US Department of Agriculture (USDA), who participated in the panel. As such, it can be difficult to classify foods according to the NOVA system, especially in countries like the US, where most foods undergo some form of processing, she says. Evidence for this difficulty comes from a 2022 study. Some 159 food researchers and experts in France were asked to classify more than 200 foods based on the NOVA system. , even when ingredient information was available. 鈥淭here鈥檚 a lot of assumptions that we need to make when classifying foods with this system, which means it can make the process a bit subjective, leading to error,鈥� says O鈥機onnor.
What鈥檚 more, it is difficult to be sure exactly how 鈥� or if 鈥� ultra-processed foods are detrimental to health. For instance, research suggests that a . But 鈥渨e don鈥檛 know the causal factor, if there is one at all, of how ultra-processed foods are causing obesity鈥�, says O鈥機onnor. Without a clear definition of the term ultra-processed, it is challenging to investigate what it is about these foods that may be harming health.
Lumping foods together under a vague label like 鈥渦ltra-processed鈥� also fails to capture the nuanced impact some of these foods have on health. In fact, a growing body of research shows that foods often classified as ultra-processed contribute important nutrients to people鈥檚 diets, particularly children鈥檚. In a study published earlier this year, O鈥機onnor and her colleagues showed that , 75 per cent of their iron intake and 48 per cent of their zinc intake, on average, came from foods considered ultra-processed according to the NOVA system. 鈥淥ne of the biggest benefits of some ultra-processed foods is the fortification of micronutrients,鈥� she says.
This means that blanket recommendations to avoid ultra-processed foods could lead to nutrient deficiencies, says at St. Catherine University in Minnesota, who also part of the panel. In a 2021 study, she and her colleagues collected dietary data from more than 12,000 people living in Australia and then modelled the effects of removing foods usually classified as ultra-processed from the diets. They found this , on average. Replacing these foods with non-processed alternatives boosted fibre consumption, but still led to lower levels of the other nutrients mentioned.
It is certainly possible for ultra-processed food to be a part of a healthy diet, says Jones. For instance, at the USDA and her colleagues recently constructed and found it had a diet quality scored of 86 out of 100. By comparison, .
What we don鈥檛 know is whether there is a mechanism as to why these foods are associated with obesity, and if so, what it is. 鈥淭here is still a lot that we don鈥檛 know about ultra-processed foods,鈥� says O鈥機onnor. 鈥淲e have to be really mindful of that because we don鈥檛 want to stigmatise any foods really.鈥� That is particularly true of foods that may contribute meaningfully to people鈥檚 diets.
