The nutritional quality of food may matter more than how much it is processed, according to new research.

Researchers say products often categorised as processed, such as canned beans, plant-based dairy alternatives, or breakfast cereals fortified with essential vitamins, can still contribute to a healthy, balanced diet.

They added that advising the public to avoid all ultra-processed food (UPF) could inadvertently hinder dietary quality, as many "healthy" processed products such as whole grain bread and canned fruit can still be “beneficial”.

The findings are based on the analysis of data from more than 200,000 people across three large studies in the US. Participants had their dietary habits tracked over several decades, from the 1980s to the 2020s, and were grouped into four categories according to their plant-based eating habits.

These categories included healthy/ultra-processed, which included plant-based milk and yoghurts, and healthy/minimally processed, including fresh fruit and nuts.

Unhealthy/ultra-processed products included fast food and fizzy drinks, and unhealthy/minimally processed items included fruit juice, potatoes and white rice.

Some 26,209 people went on to develop cardiovascular disease while around 21,000 developed type 2 diabetes and 55,493 died.

The study found that the risk of death, diabetes and cardiovascular disease varied depending on the overall quality of a person’s diet.

Those who ate more healthily had a lower risk, regardless of whether food was ultra-processed or minimally processed.

Xiaowen Wang, a postdoctoral research fellow in the department of nutrition at Harvard TH Chan School of Public Health, said: “While many ultra-processed foods tend to be of poor nutritional quality and should generally be limited or avoided, processing itself is not inherently harmful.”

Ms Wang said the findings suggest that people should focus on what they are eating overall, not just if it is processed.

“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,” she added.

“Advising people to universally ‘avoid ultra-processed foods’ can lead to lower diet quality since healthy ultra-processed foods are beneficial and unhealthy minimally processed foods are detrimental.

“People should prioritise the quality of foods rather than focusing solely on the level of processing. Aim for more nutrient-dense, high-quality foods to help lower your risk of chronic diseases.”

The findings will be presented at Nutrition 2026, the flagship meeting of the American Society for Nutrition, on July 28.