The consumption of ultra-processed foods is of great concern to consumers and this is reflected in the interest it has aroused among the scientific community. In recent years, dozens of studies have been published linking the consumption of these products to various chronic pathologies, including cardiovascular disease, diabetes, cancer and neurodegenerative diseases. 

The body of scientific research generated so far is sufficiently large to allow meta-analyses to be carried out, i.e. studies of studies with a high statistical component, which attempt to draw unifying conclusions from the evidence generated. However, these meta-analyses are specific to each pathology. The novelty of this study is that it proposes an 'umbrella' review of these meta-analyses, in order to be able to draw conclusions for all pathologies as a whole, so that guidelines and directives can be established with dietary recommendations on the consumption of ultra-processed foods. 

An important point to consider, as is done in this article, is to consider the quality of the original studies and the degree of scientific evidence they can provide. Although an enormous number of studies have been published on the relationship between ultra-processed foods and health, the vast majority of them have low or very low levels of quality (expressed as credibility levels) and grades of evidence (GRADE). This is because they are generally observational epidemiological studies which, due to their characteristics, do not allow cause and effect relationships to be established. In general, studies of this type are considered to have a low level of evidence at the outset. 

It has been suggested that nutrition recommendations should not be made with low levels of evidence and mediocre study quality and that it is necessary to have evidence based on clinical trials and their meta-analyses, which do allow causal relationships to be established. However, as discussed in the article, in the case of ultra-processed foods this is extremely complex for several reasons. One of the main reasons is that it is only possible to conduct such clinical trials for intermediate outcomes such as body weight, insulin resistance, inflammation or gut microbiota, but not for endpoint markers such as the diseases mentioned above, for ethical reasons. It should be noted that the existing evidence is sufficiently robust to suspect that administering such foods to people in a clinical trial could have dire consequences for them. 

Therefore, and this is common in nutrition, for the time being and probably in the future, it will not be possible to have high-level scientific evidence on the consumption of ultra-processed foods. In that sense, the umbrella review shows that, although low grade, the available scientific evidence is very consistent for all studies and meta-analyses published to date. In particular, relative risk levels for various pathologies have been observed to be around 30% and can be as high as 55% for obesity. 

Consequently, the study presented here is important because it reports an increased health risk associated with exposure to ultra-processed foods for virtually all pathologies. The strongest available evidence has been found for associations between increased consumption of ultra-processed foods and all-cause mortality, cardiovascular disease-related mortality, mental disorders, overweight and obesity, and type 2 diabetes. Thus, the authors recommend the implementation of public health strategies aimed at reducing dietary exposure to ultra-processed foods to improve human health.

This paper is a review that includes most of the studies published so far investigating the relationship between the consumption of ultra-processed foods and various health-related events. Therefore, as it is a compilation of several studies, it provides more evidence. 

The results of this review reflect the negative effect of ultra-processed foods on health. In particular, the results indicate that the consumption of ultra-processed foods is directly related to health problems such as heart disease, type 2 diabetes, cancer, obesity, anxiety and other mental disorders, and even mortality from various causes. 

This review therefore highlights the importance of reducing the consumption of ultra-processed foods to improve overall health and justifies the need to develop public health measures to address this problem. 

The study is based on a large sample size, as a review of several studies included data from almost 10 million people, although there are some limitations to the study - for example, the quality of evidence from the included studies was generally rated as low or very low in most cases.

In this article, researchers have summarised all the information that has been published on the long-term effect of consuming ultra-processed foods. Specifically, they have identified up to 45 articles, which summarised the published results on the association between regular consumption of ultra-processed foods and the risk of developing different diseases. The BMJ article indicates that there is very strong evidence that consumption of these foods increases the risk of developing cardiovascular disease, type 2 diabetes and mental health problems. There is also quite strong evidence that consumption of ultra-processed foods is associated with increased risk of developing obesity, sleep disturbance and premature death. 

This paper provides a very detailed picture of the impact of ultra-processed products on health, with the best scientific evidence that can be used to answer this research question: epidemiological studies in diverse populations in which participants have been repeatedly measured on their usual diet and followed to see who gets sick and who stays healthy. With the evidence that already exists, it is possible to make recommendations to the population to limit their consumption (in this sense, the 2023 Dietary Guidelines for the Spanish population already contemplate this warning) and to legislate to discourage the population from consuming these foods (taxes, warning labels or control of the advertising of these foods).

We have sufficient scientific evidence to take the necessary actions to promote the consumption of minimally processed foods and discourage the consumption of ultra-processed foods. The results of the latest systematic review on the subject conclude that consumption of ultra-processed foods is associated with poorer health outcomes, especially increased risk of mortality, metabolic and mental illness. 

This is a systematic review of existing systematic reviews, called an umbrella review. The authors synthesise the available scientific evidence on the topic. This provides an overview of the harmful effects of the consumption of ultra-processed foods on health, but does not provide any new data, such as results obtained from original research. In order to carry out systematic reviews, it is first necessary to have original articles such as those previously carried out on the subject in our environment: BMJ 2019, Mayo Clin Proc 2019. 

An important limitation of the work is the use of the GRADE scale to assess the degree of evidence, which is useful for assessing the quality of systematic reviews based on clinical trials with drugs, but not for assessing studies on nutrition. For this purpose, the use of the NUTRIGRADE scale is proposed. Nevertheless, the results of the study highlight that the scientific evidence is convincing for implementing structural measures such as the existence of taxes on ultra-processed foods in order to make fresh foods cheaper and thus make the easiest option the healthiest option, since, after all, one of the main factors influencing the eating habits of the population is the price of food. Otherwise, the social gap in health will increase without remedy.