## 2 Materials and Methods  
### Field Survey  
For the purpose of this study, a consumption survey was conducted in the second half of 2022 and the first half of 2023. It was conducted in cities and villages and included both urban and rural population on the entire territory of the Republic of Serbia. The questionnaire for the consumption survey was developed in accordance with the recommendation of the European Food Safety Authority (EFSA) to collect data on the quantity and frequency of consumption of fruits and vegetables [22]. It consisted of two main sections: (i) basic demographic characteristics for this type of study--sex of respondents, their age, height (cm) and body weight (kg) [23]; (ii) recall method for fruits and vegetables consumed. In this study, the authors combined two recall methods--food frequency questionnaire (FFQ) and 24 h food recall. Combining two recall methods is preferable because it allows modeling of different consumption scenarios [24].  
The survey was conducted face to face and targeted two groups of respondents: those over 18 years of age who could self-answer and parents of adolescents between 10 and 18 years of age. In both cases, verbal consent was obtained from respondents before the interview began, and they were fully informed about the purpose of the study and our professional commitment to uphold key ethical standards--anonymity, confidentiality and privacy [24]. Respondents were randomly selected when purchasing fresh produce at retail stores (mainly in urban areas) or by distributing the questionnaire through family and friend networks (in rural areas).  
Body mass index (BMI) was calculated using data for respondents' weight (kg) and height (m) (BMI = kg/m\({}^{2}\)) with the following categorization: (i) below 18.5--underweight; (ii) 18.5--24.9--healthy weight; (iii) 25.0 and above--overweight [25]. The reporting period for the FFQ recall methods was divided into several categories [26]: 'on an annual basis' (for food commodities that are available and/or consumed throughout the year) or 'on a seasonal basis', where the respondent could indicate the following frequencies: 'daily', 'weekly' (2-4 times per week),'monthly' (up to 3 times per month) and 'rarely' (a few times per year or never). The FFQ part of the questionnaire included 51 different fruits and vegetables belonging to another 88 food categories: (i) bakery products, (ii) soups and stews, (iii) prepared meals, (iv) salads, (v) fruits. The respondents were asked to recall their dietary habits \"in the last 12 months\".  
As for dishes, as the most complex part of the questionnaire, consisting of a variety of ingredients, they were grouped according to culinary techniques and content. The size of a meal (dishes, pastries, soups and potages) and its content were also calculated based on the recommended diet of students, which provides guidance for over 350 dishes [27]. For fresh fruit consumption, one serving was set at 150 g [28].  
The 24 h method allowed respondents to recall all types of meals, snacks, beverages and sweets they consumed 'yesterday' from morning until bedtime, including breakfast, lunch, dinner and in-between meals (various snacks). Respondents were given the opportunity to indicate the type of food (with additional description if needed) and the amount consumed as accurately as possible (in grams, pieces, cups, plates/portions, etc.). Attached to the questionnaire was a set of photographs with predefined portions, which were provided to respondents as a visual aid for both the FFQ and the 24 h recall.