Are ultra-processed foods a public health hazard?

I'll gather the latest evidence to assess whether ultra-processed foods pose a public health risk.

Yes, major public health authorities and the current epidemiological evidence increasingly treat ultra-processed foods (UPFs) as a public health hazard, although debate remains about definition, heterogeneity and mechanisms.

1. What are ultra-processed foods?

There is no single universally accepted definition, but research uses the NOVA classification system.

NOVA defines ultra-processed foods as "industrial formulations with five or more ingredients" that contain substances not typically used in culinary preparations, or more fully as industrial formulations made mostly from substances extracted from foods like oils, fats, sugars and proteins combined with additives such as preservatives, emulsifiers and artificial flavors.

Other formulations describe them as “ready-to-eat or heat-and-serve products that undergo extensive industrial processing … often containing multiple additives” that are typically energy-dense and high in sugar and salt but low in dietary fiber, protein, vitamins and minerals, and as “industrial formulations made mostly or entirely from substances extracted from other foods” with added sugars, fats, salt and cosmetic additives such as emulsifiers and flavourants.

Examples include sweetened carbonated and non-carbonated drinks, baked goods, sweet snacks, ready meals, savoury snacks, reconstituted meat products, packaged snacks, candy, and fast food.

NOVA attempts to relate levels of processing to health effects and infers that ultra-processed foods are typically unhealthy due to high fat, sugar and salt and low fiber, protein and micronutrients.

2. How prevalent is exposure?

UPFs now dominate diets in high-income countries:

Increases are fastest in low- and middle-income countries. Between 2007 and 2022 consumption increased by 40% in 22 lower-middle-income countries and by 20% in 26 upper-middle-income countries, with similar jumps in Spain (11% to 31.7%), Mexico and Brazil (10% to 23%) and China (3.5% to 10.4%). For younger, poorer or disadvantaged groups a diet comprising as much as 80% UPF is typical.

The Lancet series' central idea is that the now-global domination of UPF has caused "the displacement of long-established dietary patterns" and is driving the "escalating burden of multiple diet-related chronic diseases".

3. Evidence linking UPFs to adverse health outcomes

a) Umbrella review - BMJ 2024

The largest umbrella review to date evaluated meta-analyses of cohort, case-control and cross-sectional studies (45 pooled analyses, n=9,888,373).

Overall, direct associations were found between exposure to ultra-processed foods and 32 (71%) health parameters spanning mortality, cancer, and mental, respiratory, cardiovascular, gastrointestinal, and metabolic health outcomes. This is also summarized as exposure directly correlated with 32 (71 percent) health parameters, including mortality, cancer, and mental, respiratory, cardiovascular, gastrointestinal, and metabolic health outcomes.

Based on pre-specified evidence classification:

The most convincing or highly suggestive evidence linked diets rich in UPFs with increased risks for premature death, cardiovascular disease, mental health disorders, diabetes, obesity and sleep problems. Associations with asthma, gastrointestinal disease, some cancers and other outcomes were considered limited and needing further investigation.

The authors concluded greater exposure was associated with higher risk of adverse health outcomes, especially cardiometabolic, common mental disorder and mortality outcomes, providing a rationale to develop population-based measures to target and reduce dietary exposure.

Findings underscore need for urgent research to understand how ultra-processed foods affect health and measures to target and reduce exposure. Consistent evidence shows higher exposure is associated with increased risk of 32 damaging health outcomes including cancer, major heart and lung conditions, mental health disorders and early death.

b) Recent meta-analyses and The Lancet series

Epidemiological evidence is now described as very consistent, with large prospective studies around the world linking higher consumption with increased risk of cardiovascular disease, hypertension, stroke, heart failure and diabetes.

Prospective data also show those consuming high amounts had increased risk of death from any cause of 26% and of 58% specifically from cardiovascular diseases, and women consuming about 10 servings per day had 45% higher risk of precancerous colorectal polyps compared to those eating about three servings.

c) Experimental evidence

Researchers have also conducted clinical trials showing people who consume a diet high in ultra-processed foods tend to overeat and gain unwanted weight. The landmark Hall et al. 2019 inpatient randomized controlled trial found an extra ~500 kcal/day eaten on an ultra-processed diet, frequently cited in Lancet materials.

4. Why might UPFs be hazardous? Proposed mechanisms

Importantly, the Lancet authors and others note health risks do not stem merely from poor nutrient profiles but also from processing itself, though this remains debated.

5. Limitations and nuance

Some argue the NOVA system suffers from lack of biological plausibility so assertion that ultra-processed foods are intrinsically unhealthful is largely unproven and needs further examination, and lumps together nutritionally dissimilar products with categories too vague to support policy.

6. Public health response

Because of the breadth of associations - 71% of health parameters examined- authors and the Lancet series call for population-based measures.

Key elements include WHO recommendations to limit UPFs in national dietary guidelines and promotion of whole foods and minimally processed diets. WHO is developing its first guideline on UPF consumption with recommendations expected late 2026 or 2027, and in 2025-2030 US dietary guidance recommends limiting "highly processed packaged, prepared, ready-to-eat, or other foods that are salty or sweet".

The Lancet series emphasizes strong government policies to halt and reverse rise in UPF production, marketing and consumption, noting the main barrier is industry's corporate political activities coordinated globally to block regulation, and calls for unified global action similar to tobacco control, through taxes (e.g., sugar taxes), marketing restrictions to children, front-of-pack labelling, reformulation incentives and subsidies for minimally processed foods.

Bottom line: Based on current large-scale observational evidence synthesizing data from nearly 10 million people, higher UPF intake is consistently associated - at convincing to highly suggestive levels - with increased risks of cardiovascular death, type 2 diabetes, obesity, depression/anxiety and all-cause mortality. Public health agencies therefore increasingly view high UPF consumption as a hazard warranting policy intervention, while acknowledging that risk varies by UPF sub-type (sugary drinks, processed meats, and salty snacks drive most risk), that processing is an imperfect proxy for nutritional quality, and that more mechanistic and interventional research is needed before blanket elimination of all UPFs can be recommended.

This information is for educational purposes and does not constitute medical advice. For personalized dietary guidance, consult a healthcare professional or registered dietitian.