Researchers from the University Medical Center Groningen developed the Ultra-processed food (UPF) categorization for adults according to the NOVA classification using the Food Frequency Questionnaire Sum scores from the heart of the FFQ flower (1A Questionnaire 2). (sections: Nutrition and secondary & linked variables).

The UPF food categorization can be requested in the Lifelines catalogue. When this data has been used in your research, you will have to include a reference to the the following paper:

• Duan, M. J., Vinke, P. C., Navis, G., Corpeleijn, E., & Dekker, L. H. (2022). Ultra-processed food and incident type 2 diabetes: studying the underlying consumption patterns to unravel the health effects of this heterogeneous food category in the prospective Lifelines cohort. BMC medicine, 20(1), 1-11.

From the paper of Duan et al. (2022)
Research on UPF has been facilitated by the development of the NOVA classification. The NOVA classification is a frequently used method to categorize food and drinks based on the nature, extent, and purpose of food processing. The NOVA classification comprises four categories, ranging from un-processed/minimally processed food to UPF. According to the NOVA classification, UPF is mostly formulated from food substances and industrial ingredients that undergo a series of chemical and physical manufacturing processes. The resulting food products are often pre-packed, contain little or no intact (un-processed) food, and are considered microbiologically safe, convenient, and palatable.

Using the NOVA classification, the 110 food items from the FFQ heart were categorized in four proposed categories:

1. Unprocessed or minimally processed food: for example fresh vegetables or fruits and unprocessed meat
2. Processed culinary ingredient: for example butter or oil for cooking, sugar, and salt
3. Processed food: for example canned vegetables or fish and fruits in syrup
4. Ultra-processed food: for example processed meat, soft drinks

Per category three types of variables have been created:

• Classification variable: which adds up the intake of all food items that belong to the specific category
• Intake (nova) weight ratio variable: which indicates the weight proportion (% grams) of a specific category in the total diet of a day
• Intake (nova) energy ratio variable: which which indicates the energy ratio (grams/1000kcal) of a specific category in the total diet of a day

1. The current categorization doesn't specifically handle the reliability of energy intake (provided in the Food Frequency Questionnaire Sum scores). This could be a decision for other researchers using the UPF classification data. To make this easier, the reliability variable from the FFQ sum scores has been added as variable.
2. According to the NOVA classification, some alcohol products should also be characterized as ultra-processed food. However, we did not do this because alcohol may have separate health effects. Therefore, we analyze alcohol intake always as a separate covariate. This is also practiced by other papers from other cohorts.

* The UPF categorization according to the NOVA is included as assessment 'sec' because it is based on the FFQ sum scores.