Current food classification systems for processed foods lack consistency and consensus often leading to confusion and debate even amongst scientists, a new study in the journal Trends in Food Science & Technology, reports.

During this unique study researchers from the University of Surrey and European Food Information Council (EUFIC) reviewed over 100 scientific papers to examine if different criteria exist in developing classification systems for processed foods and, if so, what distinguishes them. Classification systems that categorize foods according to their "level of processing" have been used to predict diet quality and health outcomes, inform guidelines and in product development.

Researchers found that most classification system's criteria are not aligned with existing scientific evidence on nutrition and food processing. It is thought that this may stem from different perspectives and intentions behind the development of some classification systems.

Researchers also noted a failure to include measurements of nutritional content within some systems which may be confusing to consumers. The authors contrast this with nutrient profiling schemes such as Nutri-score, which converts the nutritional value of products into a simple code consisting of five letters.

Only a few of the classification systems examined in the analysis also acknowledge food processing done at home, and instead focus more on industrially processed foods. Researchers believe that this omission is misguided as food that is homemade is not automatically a healthier choice.

Categorization of foods deemed 'ultra-processed' and what is meant by the term, was also examined by researchers. While there is a lot of confusion and disagreement about the term, from the evidence available it is thought that these foods could relate to obesity by energy density and food properties such as texture. However, this will need confirmation through further research studies.

We found that food processing and the degree of processing used are interpreted in different ways by different classification systems. It is concerning that there are no clear agreements on what features make food more or less processed, and how this relates to healthy eating advice, which may make it more difficult for consumers to make informed choices consistently."

Christina Sadler, Postgraduate Researcher and PhD Candidate, University of Surrey

Sadler is also the Senior Manager at EUFIC. "What is needed is clarification of the underlying methods, meanings and rationales of food classification systems so that foodstuffs can be classified consistently. This will help inform public health and ensure we eat a more balanced diet."