That the diet rich in ultra-processed foods is not very healthy has already been pointed out in recent times by several studies. But now, a group of researchers have reviewed 45 separate pooled meta-analyses of 14 papers that linked ultra-processed foods with adverse health outcomes and have concluded that a diet rich in these types of foods it is associated with an increased risk of 32 adverse health outcomes, including cancer, serious heart and lung conditions, mental health disorders, and premature death. The review, published in the journal BMJ and which includes (pooling all the studies) almost 10 million participants – it becomes the largest ever done in this matter – highlights among other aspects that this type of diet increases up to a 22% risk of suffering from depression.
Ultra-processed foods, such as sweetened or salty snacks, soft drinks, instant noodles, meat products, pre-prepared pizzas and pasta dishes, cookies and confectionery, are made by combining food substances, mostly basic ingredients, and additives cosmetics (flavors, dyes and emulsifiers) thanks to industrial processes. This type of food is usually high in sugar, fat and salt, and low in vitamins, protein and fibre.
However, it can represent up to 58% of the total daily energy intake in some rich countries such as the United States – Spain is above 20% – and has increased rapidly in countries of various levels of economic development, but especially in many densely populated low- and middle-income nations.
The researchers – experts from several leading institutions, such as the Bloomberg School of Public Health at Johns Hopkins University in the US or the Sorbonne in France – rated the evidence as convincing, highly suggestive, suggestive, weak or no evidence. They also rated the quality of the evidence as high, moderate, low or very low.
Overall, the results show that greater exposure to these foods is consistently associated with a greater risk of 32 adverse health outcomes.
Compelling evidence showed that a higher intake of ultra-processed foods was associated with a 50% higher risk of cardiovascular disease-related death; between 48% and 53% suffer from anxiety and common mental disorders; and 12% type 2 diabetes.
Highly suggestive evidence also indicated that greater consumption of these products is associated with a 21% greater risk of death from any cause; between 40% and 66% of death related to heart disease, obesity, type 2 diabetes and sleep problems; and a 22% higher risk of depression.
“This very powerful study reaffirms that excessive consumption of ultra-processed foods increases the risk of certain pathologies”, explains Elena Roura, scientific director of the Fundació Alícia. “The evidence is very clear, something nutritionists, dietitians and other health specialists have been saying, and that’s why we’ve been very aware of it,” he adds.
A similar opinion is expressed by Juan Revenga, dietitian-nutritionist. “It’s raining on wet. We already knew that, and now we have more conclusive proof, although it must be taken into account that it is an observational study, in which a cause-effect cannot be established.” This aspect is also emphasized by Joana Guarch, clinical psychologist at the Clínic hospital, who points out, however, that this does not mean “that the methodology used is incorrect”.
Attention is drawn to the increased risk (22%) of suffering from depression if you follow a diet rich in this type of product. According to Roura, “the relationship is not so clear” in this specific section. He explains that when we are depressed or anxious we turn to ultra-processed foods because, in the short term, because they are rich in sugar, they give you pleasure and generate serotonin. “In the end, you don’t know if you’re depressed because you eat badly, or if you eat badly because you’re depressed”. Guarch sees it in the same way. “Is the risk in this type of food, or is it the fact of suffering from depression that increases the risk of consuming ultra-processed foods?”, he asks.
Something different is the microbiota, points out Roura. “More and more is known about the relationship between the brain and the microbiota: how you feed it has an impact on your emotions and well-being”, he concludes.
