Are ultra-processed foods a public health hazard?

Ultra-processed foods and public-health risk — I'll gather the latest evidence on what they contain and how they're linked to disease.

Yes - major health bodies and a growing body of epidemiological evidence now characterize high consumption of ultra-processed foods (UPFs) as an emerging public health hazard, although debate continues about definition, heterogeneity and causality.

1. What are ultra-processed foods?

UPFs are generally defined as industrial formulations of dyes, preservatives and additives that are not typically found in home cooking, often described as “industrial formulations with five or more ingredients” that contain substances not typically used in culinary preparations.

Most research uses the NOVA classification system, which categorises food into four groups—minimally processed, unprocessed, lightly processed, and ultra-processed. These products are characterised as industrial formulations primarily composed of chemically modified substances extracted from foods, along with additives to enhance taste, texture, appearance, and durability, with minimal to no inclusion of whole foods. Examples include packaged snacks, carbonated soft drinks, instant noodles, and ready-made meals, candies, cookies, chips, processed meats.

Consumption is high and rising. In the U.S., children get more than 60% of their daily energy intake from UPFs, in adults just over 50%. Across high income countries, the share ranges from 42% and 58% in Australia and the United States to as low as 10% and 25% in Italy and South Korea, while in low and middle income nations it is rapidly increasing. About 70% of products in the food market are estimated to be ultra-processed.

Authors differentiate UPFs from foods processed for safety reasons—like canned vegetables with only salt added—or to extend shelf life—like pasteurized milk.

2. Epidemiological evidence linking UPFs to harm

> The epidemiological evidence is now very consistent. Large prospective studies conducted around the world have linked higher consumption of ultra-processed foods with increased risk of cardiovascular disease, hypertension, stroke, heart failure and diabetes.

There is evidence that people who eat more ultra-processed foods have a higher risk of a wide range of health problems, including obesity, heart disease, type 2 diabetes and some cancers. Clinical trials show that people who consume a diet high in ultra-processed foods tend to overeat and gain unwanted weight.

The largest synthesis to date is a 2024 umbrella review in The BMJ of 45 pooled analyses (n=9,888,373):

Other meta-analyses report:

A separate global review of nearly 10 million participants underscores consistent associations with 32 damaging health outcomes including cancer, major heart and lung conditions, mental health disorders, and early death.

3. WHO and public-health framing

The World Health Organization listed UPFs and alcohol among four products that cause 19 million deaths per year globally, with UPFs and alcohol alongside tobacco and fossil fuels causing 34% of global deaths each year.

In its European region report, WHO said commercial determinants including unhealthy diets drive ill-health and premature mortality from non-communicable diseases such as cardiovascular diseases, cancers and diabetes, attributing 117,290 deaths per year to diets high in processed meats and 252,187 to diets high in salt, noting these figures do not include deaths from obesity, hypertension and high cholesterol linked to unhealthy diets.

The BMJ review concluded findings provide a rationale to develop and evaluate population based and public health measures to target and reduce dietary exposure to ultra-processed foods for improved human health. Review authors also note that reducing these foods and choosing more natural alternatives may help prevent disease, and that shifting toward minimally processed diets supports cardiovascular health.

4. Proposed mechanisms - beyond poor nutrition

Evidence suggests UPFs harm health not only through higher energy, salt, sugar, saturated fat and lower fibre/vitamins, but through non-nutritional factors.

The review highlights proposed mechanisms including gut microbiome disruption, chronic inflammation driven by NF-κB activation, and oxidative stress linked to specific additives.

Emerging evidence suggests UPF additives may increase CVD risk through inflammatory and oxidative pathways. Preservatives, emulsifiers, and synthetic colorants can disrupt gut microbial balance by reducing beneficial bacteria while promoting pro-inflammatory species. This dysbiosis can impair barrier integrity, promote endotoxemia, and trigger systemic immune activation, with NF-κB driving release of inflammatory cytokines including IL-6 and TNF-α. Oxidative stress via reactive oxygen species reinforces NF-κB signaling, creating a self-perpetuating cycle of inflammation and vascular injury.

Links persisted even after adjusting for overall nutrient profiles, suggesting non-nutritional factors contribute. Among NutriNet-Santé participants, higher consumption of emulsifiers including carboxymethylcellulose, trisodium phosphate, and fatty acid-derived glycerol esters was associated with increased CVD events (HRs 1.03-1.07).

Other work notes alterations in the food matrix during intensive processing may affect digestion, nutrient absorption, and satiety, and that additives including non-sugar sweeteners, emulsifiers, colorants, and nitrates/nitrites have been linked to detrimental outcomes and that multiple additives may have a "cocktail effect".

5. Limitations and nuance - not all UPFs equal?

Despite strong associations, most evidence is observational. The BMJ umbrella review rated 22 pooled analyses as low quality, 19 as very low, and only four as moderate quality using GRADE. The NOVA classification has been criticised as vague, based on non-exhaustive lists and subjective examples, though it remains the most frequently used classification in epidemiological studies.

Industry and some researchers argue:

Public health experts counter that harmful attributes co-occur systematically in UPFs as a consequence of manufacturing processes and ingredients needed to achieve their commercial purpose and that humans are “not biologically adapted” to these products which often contain additives, emulsifiers, colorings.

6. Bottom line

Current consensus among WHO, the BMJ umbrella review and large cohort studies is that high and frequent consumption of UPFs - especially sugar-sweetened beverages, processed meats, packaged snacks, ready meals and sweets - is consistently associated with higher risks of obesity, type 2 diabetes, cardiovascular disease and mortality, mental disorders and other outcomes, with dose-response relationships. Because UPFs tend to be cheaper, more convenient and dominate food supply, reducing intake is framed as a modifiable cardiovascular prevention strategy.

However, risk is proportional to overall dietary pattern and type/quantity of UPF consumed; reformulation, occasional consumption, and nutritionally better UPFs (e.g., whole-grain fortified cereals, plant-based meat alternatives) may not carry the same risk, and definitive causal proof from randomized trials is still limited. Public health guidance therefore emphasizes limiting UPFs, prioritizing vegetables, fruits, whole grains, legumes and nuts, and making incremental switches to minimally processed foods, rather than eliminating all processed foods entirely.