Reacción a "Study shows correlations between consumption of different types of ultra-processed foods and mortality"

Once again, it is observed that the consumption of ultra-processed foods increases the risk of mortality from all causes, so we have more scientific evidence supporting the need to take urgent measures to discourage their consumption and promote the consumption of fresh and minimally processed foods. 

This time the results come from a large observational study with a very solid scientific methodology and repeated measures of the diet, analyzing data from two American cohort studies: the Nurses' Health Study and the Health Professionals Follow-up Study carried out at Harvard University. The analyses include 74,563 women and 39,501 men without cancer, cardiovascular disease, or diabetes at the beginning of the study. There were 30,188 deaths in women and 18,005 deaths in men after a median follow-up of 34 and 31 years, respectively. 

Unlike previous results, the authors did not find an association of risk with cardiovascular mortality or cancer, so the observed risk relationship may be explained by an increase in neurodegenerative mortality and other causes. According to the authors, these differences are because other studies include distilled beverages in the calculation of ultra-processed foods and do not adequately consider smoking habits throughout life. This claim is not correct, as at least one of the published studies did adjust the analyses for pack-years of consumption, and when the effect of ultra-processed foods on never-smokers —restriction: no tobacco confusion was observed—even higher risk was observed.  

On the other hand, the authors, based on their results, conclude that the nutritional quality of ultra-processed foods has a more predominant influence on mortality than the consumption per se of these foods. However, there is a lot of previous literature that states that the risk relationship of ultra-processed foods with health is due not only to their nutritional quality but also to their processing. In fact, previous results from the SUN cohort showed that even with equal intake of saturated fatty acids, trans fatty acids, added sugars, sodium, or taking into account adherence to the Mediterranean diet, ultra-processed foods remained a risk factor for mortality. 

In addition to the nutritional quality, different reasons have been postulated that can explain this dangerous effect: overconsumption of these foods due to their easy consumption and great palatability; displacement of other more nutritious foods; lack of intake of health-protective phytochemicals present in fruits, vegetables, and legumes; presence of toxic contaminants created during processing or released from packaging materials; and consumption of a 'cocktail' of potentially harmful additives to health if consumed together and in the long term.  

The NOVA system for classifying foods according to their degree of processing has not been without criticism for being a classification that includes a wide variety of food groups, as suggested by the article's authors. Indeed, it is not perfect, but it is a clear, useful, and easy-to-apply classification that can be incorporated into public health messages reminding the importance of consuming fresh and minimally processed foods to gain health and many years of life without disability.