Not all ultra-processed foods are created equal. Here are the 4 UPFs linked with early death in a study.

• Ultra-processed foods have been associated with multiple health conditions.
• Eating certain types of UPFs carries a higher risk of early death than others, a new study found. 
• Processed meat and sweetened drinks had strong links to dying of any cause.

People who eat a lot of ultra-processed foods are more likely to die early than those who don't, according to a study. But certain foods appeared to increase the risk more than others.

Processed meat, drinks sweetened with sugar or artificially, dairy-based desserts, and sugary breakfast foods were linked with dying earlier from any cause, the authors of the study published in The BMJ found. Processed meat, in particular, carried the highest risk.

Lead study author Dr. Mingyang Song, associate professor of clinical epidemiology and nutrition at Harvard T.H. Chan School of Public Health, told CNN that the association between UPFs and early death was "moderate" and not equally strong among all UPFs. "The positive association is mainly driven by a few subgroups," he told the outlet.

The link between UPFs and death appeared to be reduced if a person's overall diet was healthy, but the authors said the findings suggest eating as few UPFs as possible is likely to be beneficial for long-term health.

"Our data together suggest that dietary quality has a predominant influence on long-term health, whereas the additional effect of food processing is likely to be limited," the authors wrote.

To make the findings, researchers from multiple universities looked at existing data on more than 100,000 US healthcare professionals. The participants had no history of cancer, cardiovascular disease, or diabetes when they signed up to provide information on their health, diet, and lifestyle habits every two years between 1986 and 2018.

The researchers also took into account how closely the participants' diets adhered to the Alternative Healthy Eating Index, a rating system that measures how nutritious a person's diet is and predicts their risk of developing chronic diseases.

The group who ate the least UPFs averaged around three servings a day, while the group who ate the most averaged seven servings a day, according to the study. The group who ate the most UPFs had a 4% higher risk of dying from any cause compared to those who ate the least, and a 9% increased risk of dying from causes other than cancer or cardiovascular diseases. This included deaths related to respiratory or neurodegenerative conditions such as Alzheimer's and Parkinson's disease.

Certain UPFs seemed to be more harmful than others

UPFs typically contain ingredients not found in a regular kitchen and are made using industrialized techniques. A wealth of research has found associations between a diet high in UPFs and poor health outcomes. Notably, a recent study linked UPFs to 32 health problems, including cancer, cardiovascular disease, and depression. But the studies, including this latest one, are typically observational, meaning it's difficult to prove that UPFs cause ill health.

Equally, as UPFs tend to be high in saturated fat, refined sugar, and salt and low in fiber and other nutrients, as noted in the study, there's an ongoing debate over whether the processing and additives are behind the link to poor health or their low nutrient profile.

UPF is also a wide category encompassing soda and candy to packaged whole wheat bread. To address these concerns, the researchers placed UPFs into nine groups to assess if some foods had a greater impact than others.

The groups were:

• Ultra-processed breads and breakfast foods
• Fats, condiments, and sauces
• Packaged sweet snacks and desserts
• Sugar-sweetened and artificially sweetened beverages
• Ready-to-eat or heat dishes
• Meat, poultry, seafood-based ready-to-eat products such as processed meat
• Packaged savory snacks
• Dairy-based desserts
• Other

Gunter Kuhnle, professor of nutrition and food Science at the University of Reading, UK, who was not involved in the study, said that despite the large sample size, the questionnaires used were never designed to determine UPF intake, and "it is therefore impossible to know how reliable results are."

Future studies are needed to improve the classification of UPFs and confirm the findings in other populations, the authors said.