Eating ultra-processed foods is linked to the risk of developing long-term health problems, according to the latest evidence from an umbrella study conducted by an international team of researchers (1).
But questions remain on just how much do these ready-to-eat products affect our well-being and should they all be assessed under the same umbrella.
An umbrella approach to assessing ultra-processed food effects
A growing body of evidence suggests that eating certain ultra-processed foods may affect our risk of developing chronic diseases (2). However, while multiple meta-analyses have examined observational studies on the associations between ultra-processed foods and health outcomes, no one has carried out a comprehensive data review. Until now…
To bridge the gap, researchers from Australia, France, Ireland, and the USA set out to test the strength of evidence relating to the link between ultra-processed foods and health. They performed an umbrella review of data from 14 meta-analyses in nearly 10 million participants, evaluating a range of health outcomes including mortality, cancer, and mental health, respiratory, cardiovascular, gastrointestinal, and metabolic disorders. Here’s what they found…
Overall, ultra-processed foods are associated with poor health outcomes
Eating more ultra-processed foods (UPFs) was consistently associated with a higher risk of adverse health outcomes. However, the strength of evidence varied, and the quality of evidence was generally low, pointing to a need for further robust research.
Among the most convincing evidence, the study found that greater consumption of ultra-processed foods was linked to higher risks of cardiovascular disease-related mortality, common mental disorder outcomes, and type 2 diabetes.
UPFs were also associated with all-cause mortality, heart disease-related mortality, depressive outcomes, adverse sleep-related outcomes, wheezing, and obesity. The researchers found weak or no evidence for connections with other conditions including cancer-related deaths, asthma, and ulcerative colitis.
Ultra-processing can alter the nutrient composition and matrix effects of foods
So, what are the mechanisms behind the link between ultra-processed foods and poor health outcomes? Evidence indicates that ultra-processed foods differ from unprocessed foods in several ways:
- UPFs differ from unprocessed or minimally-processed foods and often have poorer nutrient profiles.
- They may displace more nutritious foods in diets, resulting in a reduce intake of beneficial bioactive compounds (3).
- As a result, diets rich in UPFs are associated with markers of poor diet quality, such as high levels of added sugars, saturated fat, and sodium, high energy density and low levels of fiber, protein, and micronutrients (3).
- Finally, processing, ingredients or by-products can cause alterations to the food matrix – the physical and chemical structure of foods – which may affect digestion, nutrient absorption, and feelings of satiety (4).
Different types of ultra-processed foods may have different health effects
One limitation of umbrella reviews is that they tend to provide only a high-level overview – for example, this study did not consider possible differences in the effects of various types of ultra-processed food on chronic disease outcomes.
For example, a meta-analysis included in this umbrella review found that while eating certain types of UPF was associated with a higher risk of type 2 diabetes, other types – such as cereals, dark/wholegrain bread, packaged savoury snacks, fruit-based products, yogurt and dairy-based desserts – were associated with a lower risk (5).
These findings demonstrate the complexity of relationships between ultra-processed foods consumption and health outcomes and highlight the need for further research to understand the mechanisms behind potential associations:
- For some experts, understanding the differences between types of UPFs and within subcategories of UPFs may help consumers to adopt healthier dietary patterns, compared to maximally reducing their consumption on the whole.
- Others propose to focus on the overall quality of the diet, based on the hypothesis that a high-calorie diet, consisting of foods that are not nutrient-dense, may be harmful for health, which is confirmed by this approach that considers UPFs.
As we still do not have enough knowledge on this subject, it is necessary to look at the overall quality of the diet and the health effects across the subgroups within the NOVA category,
“Although our umbrella review provides a systematic synthesis of the role of ultra-processed dietary patterns in chronic disease outcomes, a related consideration is the possible heterogeneity of associations between subgroups and subcategories of ultra-processed foods and chronic disease outcomes”– Lane MM, et al., 2024
How do we define ultra-processed foods?
Ultra-processed foods, encompass a broad range of ready-to-eat products including packaged snacks, carbonated soft drinks, instant noodles, or ready-made meals (6). They are defined by the following characteristics (7):
- Primarily composed of chemically modified substances extracted from foods
- Contain additives to enhance taste, texture, appearance, and durability
While various systems have been developed to classify foods on the basis of processing, the most commonly used is the Nova food classification system (8). Nova has received recognition from global health and nutrition bodies including the United Nations and the World Health Organization. However, the Nova classification system has also received criticism, with concerns raised about possible imprecision and inconsistencies.
For more information on food processing, see Food processing explained.
Source: (1) Lane MM, Gamage E, Du S, et al. Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. BMJ. 2024 Feb 28:384:e077310.
Additional references
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Chassaing B. Ultra-processed foods and human health: from epidemiological evidence to mechanistic insights. Lancet Gastroenterol Hepatol 2022;7:1128-40.
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Martini D, Godos J, Bonaccio M, Vitaglione P, Grosso G. Ultra-Processed Foods and Nutritional Dietary Profile: A Meta-Analysis of Nationally Representative Samples. Nutrients 2021;13:3390
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Fardet A. Minimally processed foods are more satiating and less hyperglycemic than ultra-processed foods: a preliminary study with 98 ready-to-eat foods. Food Funct 2016;7:2338-46.
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Chen Z, Khandpur N, Desjardins C, et al. Ultra-Processed Food Consumption and Risk of Type 2 Diabetes: Three Large Prospective U.S. Cohort Studies. Diabetes Care 2023;46:1335-44.
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Monteiro CA, Cannon G, Lawrence M, et al. Ultra-processed foods, diet quality, and health using the NOVA classification system. Food and Agriculture Organization of the United Nations. Food and Agriculture Organization, 2019.
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Monteiro CA, Cannon G, Levy RB, et al. Ultra-processed foods: what they are and how to identify them. Public Health Nutr 2019;22:936-41.
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Monteiro CA, Cannon G, Moubarac J-C, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr 2018;21:5-17.
