A recent study involving over 200,000 American adults from the 1980s through the 2020s suggests that the nutritional quality of food has a greater impact on health outcomes than the degree of industrial processing. The research, led by Harvard University scientists, challenges the commonly held view that all ultra-processed foods (UPFs) should be avoided, emphasizing instead the importance of diet quality regardless of food processing levels.
The study categorized participants’ diets into four groups based on nutritional quality and processing: healthy/ultra-processed, healthy/minimally processed, unhealthy/ultra-processed, and unhealthy/minimally processed. Examples of healthy ultra-processed foods included fortified breakfast cereals, whole grain bread, plant-based milk, and canned fruits and beans. Unhealthy ultra-processed foods comprised mainly fast food and sugary soft drinks, while unhealthy minimally processed items included foods like white rice, fruit juice, and potatoes.
Over the course of the study, approximately 26,000 participants developed heart disease, 21,000 were diagnosed with type 2 diabetes, and 55,000 died. The analysis found that individuals with healthier diets had a lower risk of these outcomes, independent of whether their food choices were comprised mostly of minimally processed or ultra-processed items. Conversely, diets of poor nutritional quality — whether consisting of processed or minimally processed foods — were linked to elevated health risks.
Dr. Xiaowen Wang of Harvard’s TH Chan School of Public Health, a lead author of the study, remarked that while many ultra-processed foods tend to be nutritionally poor and should generally be limited, processing itself is not inherently harmful. “A healthy plant-based diet rich in whole grains, fruits, vegetables, nuts, legumes and healthy plant oils is beneficial, even if it includes some processed foods,” Wang said. The team used the Nova classification system, which evaluates foods based on their extent of industrial processing, including the presence of ingredients uncommon in home kitchens such as emulsifiers.
Public health experts not involved in the study noted the research offers a needed perspective amid widespread concerns about UPFs. Dr. Beverley O’Hara, a lecturer in public health nutrition, described the findings as “an important counterbalance” to earlier studies she characterized as generating excessive alarm over processed foods.
The study’s findings suggest that focusing solely on the level of processing may be overly simplistic. Instead, prioritizing the overall nutritional quality of foods—whether processed or minimally processed—may be a more effective approach for guiding dietary recommendations aimed at reducing the risks of cardiovascular disease, type 2 diabetes, and premature death.