In a recent study published in BMJ, researchers reviewed existing meta-analytic evidence on the association between ultra-processed food exposure and chronic disease outcomes.
Study: Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. Image Credit: FabrikaSimf/Shutterstock.com
Background
Ultra-processed foods, such as packaged snacks, quick noodles, and ready-made meals, are industrial compositions that include chemically manipulated ingredients and additives.
They are consumed extensively in low- and middle-income nations and are related to behavioral processes, eating surroundings, and marketing pressures.
These foods have low nutritional profiles, with higher levels of calories, salt, sugar, and saturated fat but lower levels of dietary fiber, micronutrients, and vitamins, which may synergistically influence chronic inflammatory disorders.
Several meta-analyses have examined the link between ultra-processed foods and adverse health outcomes; however, comprehensive evaluations of current evidence still need to be included.
Further research could improve our understanding of these relationships and provide valuable insights to improve public health policies and practices. It is especially noteworthy given the ongoing global debate on the necessity of public health policies to combat ultra-processed food exposure in general populations.
About the study
In the present umbrella review, researchers examined current data from meta-analyses of observational epidemiological studies investigating the link between ultra-processed food intake and the likelihood of unfavorable health consequences.
The team searched the Embase, PsycINFO, the Cochrane Database of Systematic Reviews, and the MEDLINE databases and their reference lists between 2009 and June 2023 without language restrictions.
Eligible studies included systematic review and meta-analytical research of cross-sectional, cohort, and case-control studies using the Nova food classification to determine ultra-processed food exposure among humans of all ages, regardless of health status, to compare dose-response and non-dose-response associations of dietary ultra-processed food intake and adverse health endpoints.
The team applied pre-determined evidence classifications to assess evidence credibility, graded as class I (convincing), class II (highly suggestive data), class III (representative), class IV (weak), or class V (no evidence).
They used the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach to assess evidence quality. Two researchers performed data screening and resolved disagreements by consensus.
The team included the latest meta-analysis study in case of multiple pooled analyses for the same adverse health outcome, analyzing meta-analyzed effect estimates of non-dose-response and dose-response exposure to ultra-processed foods.
They obtained missing or unclear information from meta-analysis studies by reviewing original research articles or directly requesting it from the corresponding authors. If discrepancies existed, the team prioritized extracting data from the original research article.
They performed random effects modeling to analyze the effect estimates for each endpoint, used I2 values to assess study heterogeneity, and used Egger’s regression asymmetry tests to evaluate the influence of small studies.
Results
The team identified 45 distinct pooled data analyses, including 32 non-dose-response relationships and 13 of the non-dose-response type (n=9,888,373). They found high and moderate heterogeneity in eight and 13 unique pooled analyses.
There were direct associations between ultra-processed food exposure and 32 health characteristics related to cancer, mortality, and respiratory, mental, gastrointestinal, and cardiometabolic disease outcomes.
Class I evidence indicated direct relationships between higher ultra-processed food consumption and increased risks of new-onset heart disease-associated deaths [risk ratio (RR), 1.5; GRADE evidence, very-low quality evidence], diabetes mellitus type 2 (dose-response RR, 1.1; moderate-quality evidence), anxiety [odds ratio (OR), 1.5; low-quality evidence], and mental disorders (OR, 1.5; low-quality evidence).
Class II data indicated increased ultra-processed food exposure directly related to elevated risks of any-cause mortality (RR, 1.2; low-quality evidence), cardiovascular disease-associated deaths [hazard ratio (HR), 1.7; low], diabetes mellitus type 2 (OR, 1.4; very-low quality evidence), and depression (HR, 1.2; low-quality evidence), with increased risks of adverse sleep-associated outcomes (OR, 1.4; low-quality evidence), obesity (OR, 1.6; low-quality evidence), and wheezing (RR, 1.4; low-quality evidence).
Among the other 34 pooled records, 21 and 13 had class III to IV and V evidence, respectively. The team rated 22, 19, and four pooled analyses as low, very low, and moderate quality, respectively.
Conclusions
Overall, the study findings showed higher ultra-processed-type food exposure associated with an increased risk of chronic disease outcomes, particularly cardiometabolic diseases, mental disorders, and death.
The study results provide a basis for developing and assessing the efficacy of public health initiatives to limit ultra-processed food exposure for enhanced well-being. The findings could also assist crucial mechanistic research.
Ultra-processed diets are related to ill health and early death due to lower nutritional profiles, the displacement of non-processed foods, and structural changes in consumables.
They are associated with chronic diseases via inflammatory pathways, and industrial processing methods, components, byproducts, additives, hazardous compounds, and packaging pollutants may alter them.
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