Ultraprocessed foods may harm health far beyond calories, major new review finds

A growing body of scientific evidence suggests ultraprocessed foods may damage metabolic, reproductive and immune health in ways that go far beyond excess calories or poor nutrition, according to a major new review published this month.

The report, led by Dr. Mathilde Touvier, argues that the health risks linked to ultraprocessed foods, or UPFs, are rooted not only in what they contain, but in how they are manufactured, marketed and absorbed by the body. It concludes that these products may disrupt biological systems through multiple pathways that traditional nutrition science has struggled to explain.

UPFs, such as packaged snacks, sugary cereals, fast food, sweetened drinks and ready-to-eat meals, are typically made in factories using refined ingredients, additives and preservatives designed to enhance flavour, texture and shelf life. According to the review, they are often engineered to encourage overconsumption and replace whole foods such as fruits, vegetables, meats and grains.

“UPF consumption leads to an average caloric excess and contributes to displacing the consumption of nutritionally healthy foods,” Touvier wrote, as reported in the Defender. “These factors are among the possible explanations for the effects of UPF on health, but they do not explain their whole impact.”

Recent research is beginning to fill that gap. A large meta-analysis published this month found that diets heavy in ultraprocessed foods are displacing traditional eating patterns worldwide, reducing overall diet quality and increasing the risk of chronic diseases. Researchers noted that the scale of harm mirrors, in reverse, the protective effects associated with Mediterranean-style diets.

Scientists have long been puzzled by findings showing that people consuming UPFs experience higher rates of obesity, diabetes, heart disease, infertility, immune dysfunction and shorter lifespan, even when calorie intake is similar to those eating minimally processed diets. According to the report, several mechanisms now appear to explain why.

Ultraprocessed foods are often broken down and reassembled in ways that alter how quickly they are eaten and how nutrients are absorbed. They are commonly stored for long periods and sometimes heated in their packaging, allowing chemicals to migrate into food. Many are also designed to be hyper-palatable, stimulating reward pathways in the brain in ways that resemble addictive behavior.

Additives once considered harmless are now under closer scrutiny. Research from the past five years suggests some emulsifiers, sweeteners and preservatives can alter gut bacteria, disrupt metabolism and increase chronic disease risk.

Among the studies cited is a randomized controlled trial showing that young men placed on UPF-heavy diets experienced weight gain, worsening cholesterol, hormonal changes linked to energy use and sperm production, reduced sperm motility and elevated levels of chemicals associated with food packaging. Other research linked emulsifiers to higher diabetes risk and found that adolescents exposed to ultraprocessed diets consumed more food and ate when not hungry after just two weeks.

The report also highlights what it calls a major regulatory blind spot. Food safety agencies have largely relied on decades-old testing methods that assess additives individually and focus on short-term toxicity. In reality, consumers are exposed to complex mixtures of additives over a lifetime.

“So far, safety assessments of food additives have been performed substance by substance, while mixtures of additives are consumed daily by billions of people worldwide,” Touvier wrote.

Evidence supporting that concern is growing. A large cohort study linked combinations of additives, rather than single substances, to increased Type 2 diabetes risk. Laboratory research has also shown that additive mixtures can damage human cells even when individual components appear safe on their own.

Touvier argues the science is now strong enough to justify immediate public health action. In the United States, San Francisco has filed the first government lawsuit against major ultraprocessed food producers, while more than 100 state-level bills targeting food ingredients were introduced in 2025.

She says meaningful change will require clearer labeling, tighter marketing rules, better education and policies that make minimally processed, nutritious foods affordable and accessible.

“Existing evidence is sufficiently strong to warrant immediate public health actions to lower UPF exposure,” the report concludes.

Image credit: Ishaq Robin