Are ultra-processed foods a public health hazard?

Yes — the accumulating scientific evidence strongly suggests that ultra-processed foods (UPFs) are a significant public health hazard, though some nuances and scientific debates remain about mechanisms and definitions.

The Evidence Is Substantial and Growing

Scale of consumption: UPF currently make up more than half of what U.S. adults eat on a daily basis, and two-thirds of what kids and teens eat. UPFs now account for over half of all calories consumed in the US, UK and Australia, with intake rising worldwide.

Breadth of health harms: A major 2024 umbrella review in The BMJ examined 45 distinct pooled meta-analyses from 14 review articles associating ultra-processed foods with adverse health outcomes, published in the past three years and involving almost 10 million participants. It found that higher exposure to ultra-processed foods was consistently associated with an increased risk of 32 adverse health outcomes, and importantly, rigorous and prespecified systematic methods to evaluate credibility suggest the results withstand scrutiny, supporting urgent mechanistic research.

Specific findings from this review include "convincing" evidence that a diet high in ultra-processed foods increases the risk of death from cardiovascular disease by 50% and the risk of anxiety by 48%, plus "highly suggestive" evidence linking it to a 66% higher risk of death from heart disease, 55% higher obesity risk, 41% higher sleep disorder risk, 40% higher Type 2 diabetes risk, 21% higher all-cause mortality, and 20% higher depression risk.

2025 Lancet series: More than 40 global health experts published a landmark three-paper series concluding that UPF are a leading contributor to chronic disease, with evidence that ultra-processed diets are linked to chronic health conditions like increased risk of becoming overweight and obesity, type 2 diabetes, high blood pressure, heart disease, chronic kidney disease and overall higher death rates. The authors went further than previous caution, arguing in the Lancet that these foods present too great a danger to wait any longer, calling for action, and pushed back against industry-funded skepticism, comparing it to "manufacture scientific doubt" tactics similar to those used by the tobacco industry.

Specific disease links continue to emerge: A 2025 study in JAMA Oncology from Harvard found that younger women who eat more UPF, including highly processed bread, breakfast food and soda, may be more likely to develop colorectal cancer, based on a robust data set of nearly 30,000 nurses. Separately, newer meta-analyses report a 13% higher diabetes risk for each 10% increase in UPF consumption, and an updated analysis of 18 cohort studies including more than 1.1 million participants reported a 15% higher risk of all-cause mortality among individuals with the highest UPF intake, with roughly a 10% increase in mortality risk for each additional 10% of UPF in the diet.

Moving beyond correlation: Critically, 2025 brought experimental evidence that strengthens causal claims. A 2025 randomized controlled trial showed harmful effects of UPFs on weight gain and metabolic and reproductive health, regardless of excessive caloric intake. Similarly, a randomized controlled crossover feeding trial found that consuming an ultra-processed diet for 3 weeks resulted in adverse changes in body weight and lipid profiles.

Why These Foods May Be Harmful

Researchers point to several mechanisms beyond simple nutrient content: these products can compromise nutritional quality while promoting hedonistic hunger and disrupting the gut microbiota. Other proposed pathways include dysregulation of blood lipid profiles, alterations in gut microbiota composition, promotion of obesity, induction of systemic inflammation, and exacerbation of oxidative stress.

Important Caveats

The picture isn't without controversy. There has been intense debate in scientific circles about UPFs, with some health and nutrition experts raising concerns that the term is vaguely defined and that more research is needed. One expert noted a key limitation: "One issue with the studies they looked at is that the relative risks are not very high. They are 1.1-fold to 1.5-fold increases."

There's also a classification problem — foods traditionally thought healthy, such as plant-based milks and some breads and canned vegetables, could be considered ultra-processed under current definitions, making it harder to pinpoint exactly which component of "ultra-processing" (additives, texture, fiber loss, or something else) drives the harm.

Bottom Line

Despite ongoing debate about precise mechanisms and definitions, the weight of evidence — spanning large cohort studies, umbrella reviews, and now randomized controlled trials — supports treating heavy UPF consumption as a genuine public health concern linked to obesity, diabetes, cardiovascular disease, certain cancers, mental health disorders, and premature death. The scientific consensus has shifted enough that triangulation through combining large-scale cohort studies with animal/in vitro models and human challenge studies provides increasingly compelling evidence that UPFs increase the risks of chronic diseases, despite regulatory action remaining limited.