Reacción a "A series of articles warns about the threat of ultra-processed foods to public health"

The paper by Monteiro and colleagues raises further concerns about ultra-processed food (UPF), providing evidence from a comprehensive review of the literature, including studies across the globe.  The meta-analysis, where results from previous epidemiology studies are averaged to examine whether they agree, shows that a wide range of chronic diseases are associated with increased consumption of ultra-processed foods.  Despite the very different study designs used to study UPF, and the widespread geographic distribution of these studies, the results show that some major chronic diseases ailing modern life are associated with increased consumption of ultra-processed food.

The complication with the analysis though is a lot of other things have happened to our food systems across this time, so association may not be causation, as the authors freely admit.  The authors also consider randomised controlled trials, which are specifically set up to test causation – this approach provides much better evidence to investigate whether UPF contributes to ill health.  The problem here is that there are a lot less of these types of trials (only two), and the main conclusion I take from the evidence is we need more randomised controlled trials to be sure of the results.  There is also a lack of evidence for mechanism in terms of what things are causing and contributing to disease.  The authors discuss whether the adverse effects of ultra-processed foods are  caused by increased free sugar, increased saturated fats, high salt content, low fibre, trans fats, acrylamide, endocrine disruptors, hyper-palatability, high non-beverage energy density, disrupted food structures, soft-texture, low-content of health-protective phytochemicals, and toxic contaminants – this is a fairly comprehensive list of all the things we are currently worried about in nutrition!  Not all ultra processed foods will have these issues, and indeed some processing we know is beneficial – for example folate fortification of bread through flour and current efforts in the UK by the food industry to reduce salt, sugar and saturated fat in certain products are the positive side of food processing.

Despite these reservations with the understanding of mechanisms that UPF may cause ill health, the overall message is that we urgently need to understand how food processing on this scale influences our health and how ultra-processed food has a major impact on our risk of developing chronic diseases.