In this validation study, the validity of the Nutri-plus module will be investigated.

The Nutri+ module is part of the TNO 360-degree diagnostics tool. The aim of this tool is to generate a holistic perspective on an individual's health; that is, in addition to biomedical health, it also maps an individual's behavior, mental health, and socio-economic environment. This tool can be used for decision support and shared decision-making in, for example, primary care. Furthermore, based on this more holistic diagnostic approach, more personalized advice or better-tailored interventions can be offered to individuals.

However, the dietary questionnaire that is currently part of the 360-degree diagnostics tool is still fairly limited; it assesses consumption in only four food groups. In contrast, the Health Council distinguishes 15 product groups. As a result, the current 360-degree diagnostics tool provides an insufficient picture of an individual's dietary intake. In order to better assess dietary behavior within the 360-degree diagnostics and to provide more appropriate advice, the dietary questionnaire was further developed last year into the so-called "Nutri+ module."

The new questionnaire consists of 38 questions on an individual's dietary intake across 17 product groups. The questionnaire and cutoff values are based on the Guidelines for Healthy Diet, where applicable further refined using the recommendations of the Netherlands Nutrition Centre. After completing the questionnaire, a profile wheel (see Figure 1) is displayed, providing insight into compliance with the guidelines for 17 product groups. In this profile wheel, a "traffic light" color is used for each product group to indicate whether an individual roughly meets the guidelines (green), consumes more than 50% of the recommended amount (orange), or consumes less than 50% of the recommended amount (red). For (sub)product groups for which no guideline exists, a grey color is shown (for example, for potatoes).

The product groups defined by the Health Council were further refined to provide participants with more detailed insight into areas of their dietary pattern that could be improved. In addition, unhealthy choices are included in the Nutri+ module, even though they are not part of the Guidelines for Healthy Diet. By assessing and displaying these in the profile wheel, individuals can also gain insight into the extent of their unhealthy choices.

With the Nutri+ module, we aim to offer a dietary intake assessment as an integral part of the 360-degree tool, enabling individuals to gain insight into their own dietary patterns and areas for improvement. These outcomes can be used to provide personalized dietary advice or interventions tailored to the individual.

Before the Nutri+ module can be used for personalized dietary assessment and advice, it must be evaluated to determine whether it provides an accurate picture of an individual's dietary intake. To this end, the outcomes of the Nutri+ module, consisting of a red-orange-green categorization, can be compared with those of an already validated method for dietary intake assessment. In the literature, (weighed) dietary recall methods are commonly used to validate dietary questionnaires, as these methods are less sensitive to underreporting than food frequency questionnaires.

In a 24-hour recall method, individuals are asked to provide detailed information about all foods and beverages consumed in the previous 24 hours. To obtain a reliable estimate of habitual dietary intake, the 24-hour recall must be repeated on multiple days in order to correct for day-to-day variation. Wageningen University & Research has developed and validated a Dutch online 24-hour dietary recall method that can be completed entirely online by participants, known as "Compl-Eat". This significantly reduces the costs and burden for both researchers and participants.

This study will consist of two phases. The first phase will involve a pre-test to assess the usability, comprehensibility, and completeness of the developed Nutri+ module among end users and experts. The insights generated will be used to further improve the Nutri+ module and the profile wheel visualization. After completion of the first phase, the second phase will commence, in which the Nutri+ module will be compared with a reference method in an evaluation study. The selected reference method for this evaluation study is a 24-hour recall using Compl-Eat.

Inclusion Criteria:

• Eligibility criteria included proficiency in the Dutch language, digital literacy, access to a laptop or PC, and consuming a typical Dutch diet. All answers to these criteria are self-reported and self-interpreted.

Exclusion Criteria:

• Exclusion criteria included recent unintentional weight loss of more than 5 kg, treatment by a medical specialist for a (chronic) disease, a history of heart attack or stroke, planned or previous bariatric surgery, and pregnancy.