Are ultra-processed foods a public health hazard?

Ultra-processed foods and your health — I'll pull the latest evidence on whether they pose a public health hazard.

Yes - The current epidemiological and clinical evidence indicates that high consumption of ultra-processed foods (UPFs) is a significant and growing public health hazard, though debate continues about causality and mechanisms.

1. What are ultra-processed foods?

There is no single regulatory definition, but the most widely used system is the NOVA Food Classification System.

> Ultra-Processed Foods (UPF; NOVA "Group 4") refers to "industrial formulations made entirely or mostly from substances extracted from foods (oils, fats, sugar, starch, and proteins), derived from food constituents (hydrogenated fats and modified starch), or synthesized in laboratories from food substrates or other organic sources (flavor enhancers, colors, and several food additives used to make the product hyperpalatable)

The Lancet summary of NOVA defines them as "formulations of ingredients, mostly of exclusive industrial use, that result from a series of industrial processes"

Examples include packaged baked goods and snacks, fizzy drinks, sugary cereals, and ready-to-eat or heat products, which undergo multiple industrial processes and often contain colours, emulsifiers, flavours, and other additives. These products also tend to be high in added sugar, fat, and/or salt, but are low in vitamins and fibre.

They can account for up to 58% of total daily energy intake in some high income countries, and have rapidly increased in many low and middle income nations in recent decades.

2. Evidence linking UPFs to adverse health outcomes

The largest synthesis to date - an umbrella review published Feb 28, 2024 in The BMJ - reviewed 45 distinct pooled meta-analyses from 14 review articles involving almost 10 million participants, none funded by UPF manufacturers.

> 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

> Based on the pre-specified evidence classification criteria, convincing evidence (class I) supported direct associations between greater ultra-processed food exposure and higher risks of incident cardiovascular disease related mortality (risk ratio 1.50, 95% confidence interval

Harvard Health summarized that review:

> When scientists graded the evidence, they found the most convincing or highly suggestive evidence linked diets rich in ultra-processed foods with increased risks for premature death, cardiovascular disease, mental health disorders, diabetes, obesity, and sleep problems

In detail:

> Convincing evidence showed that higher ultra-processed food intake was associated with around a 50% increased risk of cardiovascular disease related death, a 48-53% higher risk of anxiety and common mental disorders, and a 12% greater risk of type 2 diabetes

> Highly suggestive evidence also indicated that higher ultra-processed food intake was associated with a 21% greater risk of death from any cause, a 40-66% increased risk of heart disease related death, obesity, type 2 diabetes, and sleep problems, and a 22% increased risk of depression

Other large prospective studies around the world have been 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 experience higher risk for a wide range of health risks and problems including obesity, heart disease, type two diabetes and some cancers

Dose-response relationships have been reported:

> The relative risk of premature mortality increased by 18% with each additional serving of ultra-processed food

> higher consumption of ultraprocessed foods (more than 4 servings per day) was associated with a 62% increased risk of all cause mortality compared with lower consumption (less than 2 servings per day)

Researchers have also conducted clinical trials showing that people who consume a diet high in ultra-processed foods tend to overeat and gain unwanted weight.

The BMJ authors concluded these findings support urgent measures that target and aim to reduce dietary exposure to these products and better understand the mechanisms linking them to poor health.

A linked editorial went further, stating ultra-processed foods damage health and shorten life and calling for public policies.

3. Why might they be harmful? Proposed mechanisms

Researchers emphasize that harm is likely not due to a single nutrient, but a cluster of attributes that systematically co-occur in UPFs:

> including: disrupted food matrices and excessive energy density that accelerate eating and increase energy intake; engineered hyper-palatable formulations that override satiety; additives (e.g., emulsifiers and non-sugar sweeteners) linked to gut and metabolic dysfunction; and toxic industrial contaminants (e.g., packaging-derived chemicals)

Other theories include:

> UPFs contain a higher density of calories than fresh food, provoke overeating by combining elements such as fat and sugar, can be consumed more quickly because they are softer, or potentially contain harmful additives

Additional attributes discussed in reviews:

> Low nutrient density : High in sugar, salt, fat; low in fiber, vitamins, minerals
> engineered for taste and texture, they bypass natural satiety signals leading to overconsumption
> Additives and processing may disrupt the microbiome and promote inflammation

4. Are they officially classified as a public health hazard?

Major health authorities have not yet formally classified UPFs as a hazard in a regulatory definition, but are moving in that direction:

Proposed public health actions include:

> front-of-pack labels, restricting advertising and prohibiting sales in or near schools and hospitals, and fiscal and other measures that make unprocessed or minimally processed foods and freshly prepared meals as accessible and available as, and cheaper than, ultra-processed foods

Researchers in The BMJ studies also urge policymakers to shift priorities away from food reformulation toward promoting availability, affordability, and accessibility of unprocessed or minimally processed foods.

5. Limitations and debate

The evidence is largely observational:

> The researchers acknowledge that umbrella reviews can only provide high-level overviews and they can’t rule out the possibility that other unmeasured factors and variations in assessing ultra-processed food intake may have influenced their results

> Evidence for the associations of ultra-processed food exposure with asthma, gastrointestinal health, some cancers and cardiometabolic risk factors, such as high blood fats and low levels of ‘good’ cholesterol, remains limited

Critics note:

Food industry-linked scientists have also argued that focusing only on processing may distract from established advice about sugar, sodium, saturated fat and fiber.

Despite these caveats, authors state their use of rigorous and prespecified systematic methods suggests that the results withstand scrutiny, and that consistent associations across 32 outcomes in multinational cohorts of ~10 million people cannot be easily ignored.

6. What does this mean for individuals?

There is no need to eliminate every UPF, but health bodies consistent with the review advise:

Bottom line: Based on convincing and highly suggestive evidence from the 2024 umbrella review - linking higher UPF exposure to ~50% higher cardiovascular death, 12% higher type 2 diabetes, 48-53% higher anxiety, 21% higher all-cause mortality and 22% higher depression among 32 outcomes - most independent public health researchers now consider excess consumption of ultra-processed foods a public health hazard warranting urgent research and policy action, even as precise mechanisms and regulatory definitions are still being refined.