Most of us already know that ultra-processed foods aren’t healthy. But how much do they affect us? An umbrella review published in The BMJ analyzed 45 meta-analyses conducted in 14 countries across five continents, involving nearly 10 million participants. The review examined 32 different health outcomes, from chronic illnesses to mental health conditions. The term “ultra-processed” covered a wide range of products, including the obvious: chips, soda, processed meats…, as well as some less obvious ones, like flavored yogurts, protein bars, and even certain packaged breads. The findings suggest that the risks may be broader than expected.
What the evidence shows
Among the most robust findings: higher consumption of ultra-processed food was linked to a significantly increased risk of cardiovascular mortality, type 2 diabetes, and anxiety-related disorders. In some cases, the risk increase ranged from 20% to over 50%. Not all health outcomes showed the same level of evidence. Some links, such as those between ultra-processed foods and cancer or respiratory diseases, are emerging and require more research. Others, like the links to mental health conditions, have become more consistent over time, but still need further study to understand how and why these effects occur.
Moreover, the review doesn’t suggest that all ultra-processed foods have the same effect, nor that any consumption is harmful. However, it does point to a clear pattern: the more these foods are present in a person’s diet, the greater the risk for a range of health problems. One important clarification: this is not about any single ingredient: it’s not just sugar, or fat, or salt. It’s about the level of processing: the industrial techniques, additives, emulsifiers, colorings, and preservatives that give these products long expiration dates and hyper-palatable taste, while removing fiber, micronutrients, and the natural structures of food.
What we still don’t know
The review makes an important distinction between correlation and causation. While the associations found are often strong, these are observational studies. They show that people who eat more ultra-processed food are more likely to have certain health problems, and, in this case, these associations persist even after adjusting for factors like age, weight, education level, and physical activity. However, the review can’t prove that ultra-processed foods directly caused the problems. In fact, it’s likely that there isn’t a single cause, but that multiple factors are at play, and that these affect different people in different ways.
As well, one matter that remains uncertain is the mechanism by which these foods are harmful. Some evidence points to how ultra-processed foods affect our metabolism, spiking blood sugar and promoting inflammation. Another theory focuses on how certain additives disrupt the microbiome, which plays a key role in both physical and mental health. There’s also growing interest in how these foods influence the brain’s reward system, potentially leading to overconsumption and reduced satiety.
The takeaway
The review presented here doesn’t suggest that sporadically having an ice-cream or eating some chips is going to ruin one’s health. Nor does it urge us to eliminate from our diets all processed foods, some of which can have nutritional value. What it does highlight is a growing consensus: when a large part of the diet is made up of ultra-processed foods, health risks tend to rise. At the same time, the review highlights a clear need for more rigorous studies, especially those that can isolate cause from correlation. Not all ultra-processed foods are equal, and future research can help distinguish which ones are most harmful and for whom.
Reference
- Lane, M. M., Gamage, E., Du, S., Ashtree, D. N., McGuinness, A. J., Gauci, S., … & Marx, W. (2024). Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. bmj, 384. https://doi.org/10.1136/bmj-2023-077310
PhD in Sociology