A large proportion of the food sold in supermarkets is highly processed. Pastries, industrial pizzas, many sauces, salty starters or cold cuts belong to this group that is increasingly consumed. In Spain, on average, more than 20% of calories come from this type of product, and in Mexico it is 30% and in the USA 58%. Concern about the health effects of highly processed foods is increasing, as is that leading to consumption around the world. Today the medical journal BMJ publishes a comprehensive review of studies confirming the connection between increased consumption of these foods and diseases such as diabetes or mental illness and premature death.
Among the reviewed articles published over the past three years, which number nearly ten million people when counting their participants, the authors find “compelling evidence” that greater intake of highly processed foods is associated with increased risk Dying from cardiovascular disease, an approximately 50% increase in the risk of anxiety and other mental disorders, and a 12% increase in the risk of type 2 diabetes. At the next level of confidence, a 21% increase in the risk of death from any cause, an approximately 50% increased risk of obesity or sleep problems, and a 22% increased risk of depression were observed. In a paper by the same authors, they found that the risk of depression skyrockets when highly processed foods make up more than 30% of a person's daily diet. Researchers say there is limited evidence on gastrointestinal health or cancer risk.
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The work, led by Melissa Lane and Wolfgang Max from Deakin University in Australia, believes that the collected results provide sufficient rationale for implementing public health policies that reduce the consumption of highly processed foods and thereby improve population health. Although their data does not allow them to compare the health harm caused by these types of foods to that of tobacco or alcohol, Lane believes that some guidelines on these substances can show what may be effective in reducing the consumption of highly processed foods. “For example, warnings on packaging, such as those on cigarettes, could be effective,” says the researcher.
Miguel Ángel Martínez, professor of preventive medicine and public health at the University of Navarra, who was not involved in the work, believes that the evidence from the studies included in this review is more than enough to support “structural, not just educational” interventions to propose. to reduce consumption of highly processed foods. “We need to make them more expensive through taxes and use the revenue generated to reduce the price of healthy products such as olive oil or nuts, and not for anything else,” he explains. “It cannot be the case that healthy foods are becoming more and more expensive, because this will increase the health gap between social classes,” he emphasizes.
The article also argues for progress in researching the mechanisms that explain why these types of foods are harmful. Currently, they are known to be less nutritious and worsen the diet of those who take them, as they not only provide too much salt, fat or sugar, but also leave less space in the stomach for foods such as fruits that contain useful compounds such as polyphenols or phytoestrogens. They also contain less fiber and protein and concentrate more calories in fewer quantities. This combination can promote the development of chronic diseases caused by chronic inflammation or changes in the microbiota.
Martínez criticizes an aspect of the study that leads the authors to consider weak evidence that might be stronger with a different measurement method. “They use the GRADE system to assess the quality and strength of evidence and they made a mistake because this method was developed for clinical trials and we have long known that NutriGrade is adapted to the specific characteristics of clinical trials. “, is more appropriate. Nutrition,” he emphasizes. “With GRADE, the evidence in many nutritional studies will be weak because an observational study will be poor, and in nutrition we cannot do randomized clinical trials like we do with drugs to give people highly processed foods to see if “It hurts them because it would be unethical,” he concludes.
Pablo Alonso Coello, researcher at the Sant Pau Research Institute in Barcelona and scientific coordinator of Nutrimedia, appreciates the large amount and information collected in the review, its order and consistency, but warns that nutritional research will always have difficulty reaching a level Confidence as achieved with a drug in a clinical trial. “It is difficult to assess the influence of each factor and the impact is small,” he emphasizes. “We will never have the same certainty as with tobacco and cancer, which have very large impacts, and the researchers themselves recognize the limitations that they cannot throw into the fire,” he concludes. As an interim solution, the authors of the article published in the BMJ suggest short-term studies to test the effects of highly processed foods, measuring changes in weight, insulin resistance, microbiota or inflammation levels. It will be impossible to do the same thing long enough to find out whether they accelerate death or the development of cancer or cardiovascular disease.
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