Are ultra-processed foods a public health hazard?

I'll pull together the latest evidence on whether ultra-processed foods pose a public health hazard.

Based on the current scientific literature, the majority of researchers and public health agencies now consider diets high in ultra-processed foods (UPFs) a public health hazard, though with important nuance.

What are ultra-processed foods?

As defined by the NOVA classification system developed by Carlos Monteiro in 2009, ultra-processed foods are “industrial formulations with five or more ingredients” or more formally “snacks, drinks, ready meals, and many other products created mostly or entirely from substances extracted from foods or derived from food constituents with little, if any, intact food.”

Examples include:

These products also tend to be high in added sugar, fat, and/or salt, but are low in vitamins and fiber.

Evidence linking high UPF consumption to disease

Researchers have found links between the consumption of ultra-processed foods and a range of negative health outcomes, including obesity, cancer, heart disease, type 2 diabetes, and mental disorders, as well as an increased risk of death.

The largest synthesis to date is an umbrella review published Feb. 28, 2024 in The BMJ:

> Need more reasons to stop eating ultra-processed food? How about 32 of them? That's the number of health problems noted in the largest-ever review of studies about the dangers of diets high in ultra-processed foods. The findings, published online Feb. 28, 2024, by The BMJ, come from a review of 45 analyses published in the last three years, involving about 10 million people in total

The review carried out an umbrella review of 45 distinct pooled meta-analyses from 14 review articles involving almost 10 million participants, grading evidence as convincing, highly suggestive, suggestive, weak, or no evidence.

> Overall, the results show that higher exposure to ultra-processed foods was consistently associated with an increased risk of 32 adverse health outcomes

> Consistent evidence shows that higher exposure to ultra-processed foods is associated with an increased risk of 32 damaging health outcomes including cancer, major heart and lung conditions, mental health disorders, and early death

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.

Specifically:

> 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 studies support this:

The authors concluded:

> These findings support urgent mechanistic research and public health actions that seek to target and minimize ultra-processed food consumption for improved population health

And a linked editorial argued it is now time for United Nations agencies, with member states, to develop and implement a framework convention on ultra-processed foods similar to the framework on tobacco.

Why it is considered a population-level hazard: scale of exposure

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.

In the United States:

> The mean percentage of total calories consumed from ultra-processed foods (UPFs) eaten by everyone age 1 and older was 55%, during August 2021 and 2023... among those between the ages of 1 and 18, the mean consumption of UPFs was higher, 61.9% of calories

UPFs are extremely common, accounting for up to 70 percent of the American diet in some estimates, and have been linked in public discourse to an “epidemic” of chronic disease.

Public perception matches: More than 60% of survey respondents agreed that such foods are addictive and major causes of obesity, Type 2 diabetes and heart disease.

Nuance: Not all UPFs are equally harmful

Recent scientific advisories emphasize heterogeneity within the NOVA 4 category:

> The American Heart Association (AHA) suggests that not all ultra-processed foods (UPFs) are bad for you

> Certain processing methods help keep foods safe, nutritious, and affordable without sacrificing quality

> A new scientific advisory from the American Heart Association (AHA) has challenged the idea that all ultra-processed foods are unhealthy

> While many ultra-processed foods have been linked to adverse health outcomes, the advisory, published on August 8 in Circulation, offered a more nuanced perspective. For instance, AHA scientists argue that some UPFs appear to have better nutritional profiles and can fit into an overall healthy diet

The AHA notes that certain types of industrial food processing are beneficial for preservation and safety, and/or lowering cost, such as techniques that extend shelf life, control microbial growth, preserve nutritional and sensory qualities, and reduce food loss and waste.

Healthier UPFs tend to have more nutrients, while less healthy options are loaded with sugar, unhealthy fats, and salt.

Some examples of healthier ultra-processed foods include:

In contrast, 'less healthy' UPFs - sugar-sweetened beverages, refined snack foods, instant noodles, processed meats - are typically low in nutritional value and high in added saturated fat, sugars, and salt.

A WHO International Agency for Research on Cancer report also suggested that processed foods such as bread and cereal reduce the risk of multiple long-term conditions – multimorbidity – due to their fibre content, indicating not every UPF carries the same risk.

Researchers also acknowledge limitations: 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, and that Associations between ultra-processed foods and asthma, gastrointestinal disease, some cancers, and other health issues were limited [...] and need further investigation.

Public health implications

Because most UPFs are characterized by poor nutritional quality, contributing to excessive calories, and typically high in saturated fats, added sugars and sodium (HFSS), authors call for policies including:

Experts recommend an 80:20 approach - 80% whole foods with 20% leeway for healthier processed foods - prioritizing fiber (3g or more per serving), protein, and fortification while limiting added sugars, unhealthy fats, and sodium, and checking short, recognizable ingredient lists.

Bottom line: Based on consistent, though mostly observational, evidence from millions of participants, high consumption of typical ultra-processed foods - especially sugary drinks, processed meats, and salty/fatty packaged snacks - is widely regarded as a public health hazard associated with increased risk of cardiovascular death, type 2 diabetes, obesity, depression, anxiety and all-cause mortality. The hazard is dose-dependent and driven largely by nutritional quality and additives, not processing per se, so some fortified, fiber-rich UPFs can be part of a healthy diet when consumed in moderation.

This information is educational and not medical advice. If you are concerned about your diet, consult a healthcare professional or registered dietitian.