A new research review reports links between greater consumption of ultra-processed foods and an increased risk of 32 damaging health outcomes, with the most convincing evidence pointing to higher risks of cardiovascular disease, type 2 diabetes, and common mental health disorders.
The study published in The BMJ conducted a high-level evidence summary, or “umbrella review,” of 45 previously conducted meta-analyses from 14 review articles linking ultra-processed foods with adverse health outcomes. The review articles were all published in the past three years and involved almost 10 million participants.
The SMC asked experts to comment.
Dr Andrew Reynolds, Department of Medicine, University of Otago, comments:
“Is this something new? While this study is impressively well conducted and in a prestigious journal, it is the latest in a series of similar reviews. The last one was published less than a fortnight ago. All reviews to date have looked at the same observational associations while calling for mechanistic studies and trials to be done.
“Is this topic important? Undoubtedly. Absolutely. Yes. What we eat is incredibly important to our health. But is ultra-processing the right lens to look at the health of what we eat? This publication relies on the NOVA classification system, which ignores much of what we understand about nutrients, food groups, and dietary patterns to classify a food into one of four categories. Pound-for-pound, every food in the same category is considered equal. This means that frozen peas with mint and a sugar-coated doughnut are the same, they are both ultra-processed. Except they aren’t the same? One is a vegetable with a flavour added, the other is an occasional food, or something to be enjoyed in moderation. This new publication recognises that ‘diets rich in ultra-processed foods are associated with markers of poor diet quality, with higher levels of added sugars, saturated fat, and sodium; higher energy density; and lower fibre, protein, and micronutrients’ but does not control for these factors in its analysis.
“What should happen next? It would be really useful to understand the health effects of different food processing techniques, then how they work in combination, and then build a classification system that is based on that new knowledge and the existing knowledge of nutrients, foods, and dietary patterns. Alternatively, what we already know about healthy kai should be used to improve the food environment around us. Healthy kai is not the cheapest kai, nor is it equitably available to all New Zealanders. We could remove the barriers to healthy kai first, rather than seek new ways to identify unhealthy foods?”
Conflict of interest statement: “I am a Senior Research Fellow funded by the Heart Foundation of New Zealand. One of my research interests is the effects of food processing on cardiometabolic health.”
Dr Kathryn Bradbury, Senior Heart Foundation Fellow, Senior Research Fellow, Department of Epidemiology and Biostatistics, School of Population Health, University of Auckland, comments:
“This umbrella review looked at studies which had systematically reviewed all the available evidence on ultraprocessed food consumption and health outcomes.
“The authors of the umbrella review found that there was moderate quality evidence that eating higher amounts of ultraprocessed food increases the risk of death, type 2 diabetes, and being overweight or obese, and does not affect the risk of prostate cancer. They also found low quality evidence that eating higher amounts of ultraprocessed food may increase the risk of death from cardiovascular diseases, as well as anxiety.
“More evidence is needed to confirm these findings, and to confirm the direction of some of the relationships. For example, it is possible that having anxiety leads to eating more ultraprocessed foods, and not the other way around. We also need further research into the mechanisms of how ultraprocessed foods might influence health outcomes.
“The ultraprocessed foods category is very broad but usually includes foods and drinks that are high in calories, sugar, fat or salt. Foods like chips and fizzy drink are classified as ultraprocessed, but packaged, sliced wholegrain bread is also technically ultraprocessed, and bread is a major source of fibre in Aotearoa New Zealand. Of course, as a population we should be cutting down on fizzy drinks but wholegrain bread and some of the other foods which are categorised as ultraprocessed are actually ones we recommend in our dietary guidelines.”
No conflict of interest.
Professor Lisa Te Morenga, Research Centre for Hauora and Health, Massey University and Co-chair of Health Coalition Aotearoa, comments:
“This review confirms what most people intuitively know: some foods aren’t very healthy. This shows that one way to define unhealthy food is the term ‘ultra-processed foods’. This, however, may not be all that helpful for consumers as the term captures many foods that are highly processed but actually have a useful role in our diets because they are cheap, shelf-stable and provide good nutrition, like bread and baked beans. For people in Aotearoa New Zealand one way to help consumers identify the most healthy option in a food category, like for example breakfast cereals, would be be make the Health Star Rating system mandatory for all packaged foods.”
No conflicts of interest declared.
Professor Emeritus Elaine Rush, Auckland University of Technology, Riddet Institute, comments:
“Ultra-processed foods consist of combinations of ingredients that are put together using a series of industrial techniques and processes. Ingredients include sugar, fat and salt and these ingredients may be chemically modified and include additives that make the product tastier, more palatable and more attractive. The ingredients are usually cheap and have a long shelf-life. Food based dietary guidelines for health and the planet do not include ultra processed foods which are also often labelled as treat or occasional (once a week) foods.
“Evidence is accumulating that some food additives may cause harm – both to human function and the health of the microbes that live in the gut which in turn affect our health and well being.
“This timely and very large umbrella review pulls together evidence and analysis of many studies with around 10 million people showing that the more ultra-processed foods eaten the higher the risk of nutrition related chronic disease and loss of quality of life. It is very clear – ultra-processed foods are not good for human health. The more that are consumed the associated harm is greater. While the authors recommend population-based measures to reduce dietary exposure to ultra-processed foods, i.e. eat less ultra-processed food, they do not explicitly say what foods could be eaten instead and how they could be provided at the same cost and access. Evidence-based dietary guidelines for health recommend a diverse variety of minimally processed foods but there is a huge mismatch between what food is produced, imported, its cost and availability and what the guidelines say. It is not possible to feed all New Zealand people well given the current state of the food system. Of particular concern is the present and future health of children which is shaped by the quality of food they are exposed to from conception. Food insecurity it not being able to access nutritious food and the drivers and solutions for this involve all players in the food system.”
No conflict of interest.
Dr Sally Mackay, Co-chair Health Coalition Aotearoa Food Expert Group, Senior Lecturer, School of Population Health, University of Auckland, comments:
“The NOVA system classifies foods according to the level of processing from unprocessed/minimally processed, processed through to ultra-processed foods (UPF) (hyperpalatable foods often high in energy, sodium and sugar). This umbrella review published in The BMJ assesses the emerging body of evidence that UPFs are associated with a range of health parameters – 32 were identified in this review that are beyond the usual diet-related diseases (cardiovascular disease, diabetes, cancer) and include respiratory and mental health.
“UPFs are a large and varied food group that includes everyday items like sliced, wholegrain bread and breakfast cereals as well as the foods we typically consider ‘junk food’ like fast-food, extruded snacks, carbonated drinks and confectionery. In fact in 2018 69% of packaged foods were ultra-processed. The researchers recommend more research to understand the aspects of UPFs that are linked to poor health. This will help us translate this research into practical recommendations of which UPF are most harmful.
“However. we don’t need to wait for research to implement policies that restrict marketing of unhealthy food and beverages, mandatory display of Health Star Ratings, and a levy on sugar-sweetened beverages.”
No conflict of interest.