1. Introduction
According to the most recent Global Burden of Disease study [
1], one in five premature deaths worldwide can be attributed to unhealthy diets. The relationship between nutrients, foods, and dietary patterns has important implications, particularly for the prevention and development of chronic non-communicable diseases (NCDs) such as cardiovascular disease, cancer, and diabetes [
2,
3]. The preschool years are a time of intense growth and development and a critical period for the development of lifelong eating habits that can help reduce the burden of NCDs later in life [
4]. Although the home environment is a key factor in shaping eating habits [
5], more than 80% of preschool children in high-income countries are enrolled in pre-primary education [
6,
7], where they may spend up to 251 days/year and up to 9 hours/day [
7]. During these hours, at least three meals per day (breakfast, lunch, and snack) and often an additional snack, are consumed, which should meet more than 60% of children's daily nutritional and energy needs. This high figure suggests that meals in kindergartens can influence children's health, either to their advantage or disadvantage.
In the last decade, many European countries have implemented various measures to improve food environment in kindergartens and schools [
8]. However, the recent report of EFSA Comprehensive European Food Consumption Database [
9] shows, that European children consume very low amounts of vegetables and nuts, while fruit intake is slightly better, but still too low. Nutrition in Slovenian kindergartens is well organized, as all children have access to the high-quality food, regardless of their socioeconomic status. Nevertheless, a Slovenian survey shows that only 30% of toddlers eat vegetables daily, 60% eat fruit and 59% of Slovenian toddlers do not eat nuts at all [
10].
Most kindergartens in Slovenia are municipal (public) and provide three to four meals daily (breakfast, lunch and 1-2 snacks). The menus are prepared by a qualified staff member who is obliged to follow the national Guidelines for Healthy Eating in Educational Institutions (Guidelines) [
11]. All meals are cooked and prepared in kitchens of the kindergartens or, to a small percentage, supplied by external food providers. Children in groups of up to 22 take all meals in classrooms with one to two teachers. Guidelines are well established, but allow for some simplifications, most notably reflected in inadequate supply of vegetables, whole grains and nuts [
12]. A low supply of whole grain products, fruits and vegetables in kindergarten diets is also reported in several other studies [
13,
14,
15], and nuts are rarely mentioned, despite the positive health effects and the known contribution of inadequate intake of the above food groups to the economic burden [
16,
17,
18,
19].
Some studies have described the contribution of kindergarten nutrition to a daily intake of food groups in children [
14,
15,
20,
21], but, to our knowledge, this is the first study to compare the contribution of kindergarten menus, within the same country, with same mandatory Guidelines, to the recommended daily intake of selected food groups in children. Our objective was to determine whether a properly planned kindergarten menu can contribute to a more adequate daily intake of healthy food groups and, consequently, to a more adequate nutrient intake in children. Therefore, our study had three main objectives: 1) to create a prototype 5-day kindergarten menu in strict adherence to the Guidelines and evaluate the average supply of foods from seven food groups (fruits, vegetables, whole grains, refined grains and potatoes, nuts, meat and meat substitutes and milk and dairy products) compared to the supply of a regular (simplified) 5-day kindergarten menus. 2) Comparison of the contribution of the prototype menu to the daily intake of the above food groups among participants in the prototype group (PG) with the contribution of the regular (control) menu to the daily intake of food groups among participants in the control group (CG). 3) To compare the food intake of participants in both research groups on weekdays and the weekend, with the Recommended Daily Food Intakes (RDFI) in the Guidelines [
11].
We hypothesized that the prototype kindergarten menu would significantly contribute to a more adequate daily intake of vegetables, fruits, whole grains, and nuts with respect to the RDFI compared with regular kindergarten menus. The second hypothesis states that food group intakes among participants of PG and CG would be more consistent with the RDFI on weekdays than on the weekend.
4. Discussion
This cross-sectional experimental study is, to the best of our knowledge, the first study that comparing the contribution of the prototype and regular 5-day kindergarten menu in the same country with obligatory national dietary Guidelines, to average daily intake of food groups in 5-6-year-old participants.
We confirmed our hypothesis that kindergarten menus designed by strictly following nutritional guidelines can significantly contribute to a more adequate daily intake of vegetables, fruits whole grains and nuts in PG participants during weekdays. Results also confirmed our second hypothesis that compared to the nutrition provided outside kindergartens, kindergarten nutrition in both research groups contributed to a more optimal intake of healthy food groups; however, the contribution of the prototype menu was superior. Despite the fact that Slovenian educational institutions are obligated to prepare meals in accordance with national Guidelines, our previous study revealed that kindergarten meals can significantly differ, both in terms of offered food groups as well in terms of the content of macronutrients, minerals and antioxidants [
31].
There are only few studies examining the daily intake of food groups and/or nutrients in preschool children (under 6 years of age), some of them examining the contribution of daily nutrition inside and outside kindergartens [
14,
15,
32], others only individual meals, either at home or in kindergartens or at both places [
21,
33,
34,
35]. They all report similar outcomes, namely that organized kindergarten nutrition is on average of higher quality than nutrition outside kindergartens, which was also confirmed in our study.
Since the main goal of our study was to clarify the contribution of kindergarten nutrition to daily nutrition in participants, we focused mainly on the offer and intake of food groups in kindergartens. All menus in PG and CG kindergartens were planned in accordance with the Guidelines, which was reflected in the similar offer of all main food groups, including total offer of combined fruit and vegetables groups (331 g vs. 301 g) and combined whole grains and refined grains plus potatoes (211 vs. 223 g). However, there were significant differences in the ratio of offered vegetables and fruits, whole grains and refined grains with potatoes and offered nuts on the PG vs CG menus (
Table 1), mainly due to the greater diversity of offered foods. Namely, PG menu contained on average 14 different dishes/day, while CG menu comprised on average 10 dishes/day. The more diverse offer in PG was reflected in a significantly higher intake of vegetables, whole grains and nuts in PG kindergarten participants, corroborating the results of a recent meta-analysis which reports that food intake can be increased in the presence of variety [
36]. The results of our study are also consistent with the findings of Roe et al. [
37] that children eat more vegetables when offered a variety of different types of familiar vegetables compared to being offered a single vegetable snack. A recent study on portion sizes of vegetables and fruits shows that serving larger portions results in increased daily consumption of vegetables and fruits in children [
38], however, these foods were also wasted in bigger amounts. This was not confirmed in our study, as the amount of waste in PG kindergartens was not significantly higher than in CG kindergartens (
Supplementary Table S5), as prototype menu included dishes that children were familiar with and which comprised more vegetables, whole grains and nuts. The effectiveness of incorporating vegetables into multiple main dishes as strategies to increase vegetables intake was also confirmed in some other studies [
39].
Although the weekdays intake of vegetables was not adequate even in PG participants, their average daily weekday’s intake was significantly more optimal than average weekend intakes and weekdays intakes in CG participants whom were offered too low amount of vegetables in kindergarten. Low amounts of vegetables contained in daily kindergarten meals, only around 20% of RDFI, are also reported by some other studies from Finland [
15] and the US [
14,
38].
The prototype kindergarten menu also contributed to a more adequate daily intake of whole grains on weekdays in PG participants, while the intake of whole grains in CG participants was low during the weekdays, but still significantly higher than during the weekends. Our results strongly encourage a greater supply of whole grains in kindergartens as we revealed that replacing refined grains with whole grains can contribute to the recommended daily intake, considering that intake outside kindergarten is low. Additionally, as a result of significantly higher amount of offered vegetables and whole grains in PG kindergarten meals it is necessary to highlighted the significantly higher content of dietary fiber in meals, which was also confirmed by chemical analysis our kindergarten meals [
31]. Providing a sufficient amount of dietary fiber is very important, as the recent study states that a higher fiber intake is associated with better glucose tolerance levels and lower cardiovascular risk in children [
40]. Unfortunately, the OPEN analysis and also the chemical analysis of our kindergarten meals [
31] showed, that too much sodium/salt is used in kindergarten food preparation, which calls for immediate action, especially in terms of educating the kitchen staff.
Participants in both study groups during weekdays were consumed the recommended fruit intake, but not during the weekend, which was in the first case due to the implementation of the Slovenian national guidelines [
11] which have been mandatory in all educational institutions since 2010, and in second case due to poor eating habits among Slovenian [
10].
Our study was also focused on offer and intake of nuts, as we did not find any study that addressed the inclusion of nuts in the kindergarten diet. The EFSA report state that European children, on average has low intake or no consumption of nuts [
9], but we demonstrate in our study that we can contribute, with kindergarten nutrition only, to an adequate daily intake. In addition to their broad health benefits [
18,
41] nuts also improve overall diet quality [
42] therefore they should be more specifically addressed in dietary guidelines. It is to be pointed out that care should be taken when providing nuts to children in kindergartens, as there is a risk of suffocation, which must be considered when preparing and serving this food group. In addition, tree nut allergies are among the eight most common food allergies that may cause severe reactions [
43]. Despite all the risks, the benefits of eating nuts may exceed the possible disadvantages; therefore, nuts could be included in kindergarten menus, providing that all safety precautions are maintained.
Considering that the children are expected to consume more than 60% of their daily energy and nutritional needs (in Slovenia and some other countries even up to 75%) in kindergartens, we observed that offer in the prototype menu satisfied RDFI requirements with regard to almost all parameters, while the regular menu did not. Besides that, the 7-day participants dietary record showed that diet outside the kindergarten contained very low amounts of vegetables, whole grains and nuts, which is in accordance with EFSA report, which shows that intakes of healthy food groups are inadequate [
9]. By comparing the average amounts of food groups consumed during the week and during the weekend, when only parents take care for children’s nutrition, we can clearly distinguish the positive contribution of kindergarten nutrition, especially in providing an adequate amount of vegetables, fruits, whole grains and nuts. This contribution was also revealed in CG participants, although their weekday’s nutrition was less adequate than nutrition in PG participants. Based on results, we recommend designing kindergarten meals by strictly following the Guidelines, without simplifying. Although some healthy foods are not well accepted by children, we should try different strategies for increasing their consumption, rather than stop offering them [
44].
The results of our study coincide with the findings of several other studies [
13,
14,
21], as they show that kindergarten nutrition contributes to a more adequate daily intake of vegetables, fruits, and whole grains in the participants from both study groups. However, with our study we also revealed that by consistently following the dietary guidelines in the design of kindergarten menus, we can contribute to a significantly more adequate daily intake of vegetables, fruit, whole grains and nuts, compared to a simplified menu design, which should lead to more effective supervision of the implementation of the nutritional guidelines in kindergartens. As illustrated in
Supplementary Table S4, differences in offered food groups were seen even between dishes prepared in PG kindergartens with the same menu, as cooks including different amounts of food groups, the biggest differences being in the use of vegetables and whole grains.
Kindergarten nutrition depends on several factors, one of the most important being the ability and educational level of nutritionists and cooks who should be able to design menus and prepare healthy meals in accordance with the guidelines of healthy eating. Additional studies and national measures are needed to achieve these goals.
The main strength of our study was that we compared differently designed kindergarten menus within the same country, with the same dietary guidelines, which, to the best of our knowledge, has not been studied yet. Additionally, strength is represented by the 7-day weighted dietary record, which also includes weekends, providing a solid insight into the average amount of food groups’ intakes in 5-6-year-old children. All mixed dishes were carefully disaggregated according to weighted recipes to obtain accurate data on the content of individual food groups. Due to the relatively small number of participants, we were able to daily interact with their parents, teachers and cooks, which additionally prevented errors in filling dietary records. Data are presented in grams, which allows for the most accurate comparison with other studies. As there are no national data on the average daily intake of food groups for 5-6 years old children, our results filled the gap on missing data, although they were not representative. Furthermore, the 5- day prototype menu can be helpful for designing new menus and can be easily transferred to other kindergarten environments.
The findings of this study need to be interpreted in the light of its limitations. Since the OPEN tool does not provide discrimination between whole grain and refined starchy food products, the classification was performed manually. This could lead to a difference between the results of other studies, as the methodology for calculating whole grain foods is not yet unified. Besides relatively small number of participants, limitations is also, due to COVID-19 epidemic, a relatively short observational period.
In the last decade, many European countries have implemented various measures to improve food environment in kindergartens and schools [
8], but still, recent national surveys [
9] indicate that children do not consume a sufficient amount of food groups, which are recognized as beneficial for health. We believe that with our study, we have opened a new field of future research that should look for more sustainable ways for the most optimal intakes of recommended food groups in kindergartens.