People who ate more ultraprocessed food were more likely to develop several chronic health conditions and to die during follow-up, according to a large new analysis of research from around the world.
The study, published in Family Medicine and Community Health, combined findings from 51 long-term studies involving nearly 8.82 million adults. Higher consumption of ultraprocessed food was associated with cardiovascular disease, cancer, overweight or obesity, metabolic syndrome or diabetes, depression or anxiety, digestive disease and death from any cause. But because the research was observational, it can't show that ultraprocessed foods themselves caused those outcomes.
The researchers also looked at whether health risks changed as people ate increasing amounts of ultraprocessed food. For several conditions, higher intake was associated with progressively higher risk.
For every additional 100 grams consumed per day, the analysis found a 14% higher risk of cardiovascular events, 4% higher cancer risk, 3% higher risk of death from any cause and 2% higher risk of metabolic syndrome or diabetes.
That doesn't mean adding 100 grams of ultraprocessed food to your diet will automatically raise your personal risk by those amounts. The numbers describe patterns across large groups of people, and 100 grams can represent very different foods.
That's particularly important with ultraprocessed foods.
The studies used Nova, a system that classifies foods based on how and why they're processed. Its ultraprocessed category includes many foods people might expect, such as sugary drinks, candy and processed meats. But it can also include some breads, yogurts and nut-based products.
The researchers themselves acknowledge that as a limitation. Foods grouped together as ultraprocessed can have very different nutritional profiles and may not affect health in the same way. The analysis couldn't determine which types of ultraprocessed foods might account for the associations it found.
Still, when researchers looked across the studies, a broad pattern emerged. Compared with people who ate the least ultraprocessed food, those who ate the most had a 24% higher risk of cardiovascular events, 24% higher risk of metabolic syndrome or diabetes and 18% higher risk of death from any cause.
Associations were also found for cancer, overweight or obesity, depression or anxiety and digestive diseases.
High blood pressure was less clear. Simply comparing people who ate the most and least ultraprocessed food did not produce a statistically significant difference. However, a separate analysis looking at how risk changed as consumption increased did find an association.
There are other reasons to interpret the results cautiously.
All of the studies depended on people reporting what they ate, and remembering years of everyday eating habits accurately can be difficult. Some food questionnaires also weren't designed specifically to distinguish ultraprocessed foods from other foods.
And diet is only one part of people's lives. People who eat more ultraprocessed food may differ from those who eat less in other ways that affect health. Researchers can account for many of those differences, but they can't account for everything.
That's why the enormous number of participants doesn't turn these findings into proof that ultraprocessed foods cause disease.
The researchers themselves rated most of the evidence as low certainty. Evidence involving overweight or obesity was rated moderate, while evidence involving high blood pressure was rated very low.
The study also can't tell us exactly why higher ultraprocessed food intake was associated with poorer health. Researchers have proposed a number of possibilities, including differences in nutritional quality and how some of these foods affect how much or how quickly people eat. But this analysis wasn't designed to test those explanations.
Nor did it find a clear daily limit that separates a “safe” amount of ultraprocessed food from an unhealthy one.
Instead, the study adds to a larger body of research finding that diets higher in foods classified as ultraprocessed tend to be associated with poorer health. Its size and ability to compare different levels of consumption make that pattern harder to ignore, but they don't resolve one of the biggest questions in UPF research.
Ultraprocessed food is a broad category. Researchers still need to determine which foods within it matter most and how much of the health differences are related to processing itself, the nutritional qualities of particular foods or people's overall diets.
The study was supported by the Natural Science Foundation of China, the Natural Science Foundation in Jiangxi Province and the Jiangxi Province Thousands of Plans.