Early childhood represents a critical period for growth and development, influencing physiological, cognitive, and immune functions. Establishing healthy eating habits during this phase is crucial for preventing chronic diseases later in life. Undernutrition negatively impacts neurocognitive development and social interactions, while excessive calorie intake and unhealthy diets increase the risk of obesity and related non-communicable diseases. A healthy diet involves consuming a variety of foods in moderation, with optimal dietary behavior essential for adequate nutrition. Studies suggest that dietary quality declines between 6 months and 4 years of age, potentially due to increased consumption of processed foods. This underscores the importance of food-based dietary guidelines and public health education to promote healthy eating. While the positive impact of healthy diets on immune function is recognized (e.g., phytochemicals in fruits and vegetables reducing oxidative stress and inflammation), few studies have examined the cost-effectiveness of promoting dietary guideline adherence in preschoolers. This study addresses this gap using medical service utilization as a surrogate measure of overall health and evaluates the cost-effectiveness of promoting adherence to dietary guidelines amongst Taiwanese preschoolers. The unique characteristics of Taiwan's National Health Insurance (NHI) program—compulsory coverage with comprehensive data on medical service utilization and expenditures—provide a valuable opportunity to conduct this research. The study's aim is to investigate the association between the TCHEI and medical service utilization for all diseases and respiratory diseases in Taiwanese preschoolers.

Existing literature highlights the importance of healthy eating habits in early childhood for optimal development and long-term health. Studies have shown a decline in dietary quality from 6 months to 4 years of age, emphasizing the need for interventions to improve children's diets. Research suggests that a healthy diet strengthens the immune system, while a Western-style diet increases the risk of asthma and respiratory infections. Previous research focusing on the cost-effectiveness of promoting dietary guidelines in preschoolers is limited. A study by Kirk et al. indicated a potential association between a higher healthy eating score and lower medical service utilization in Canadian elementary school children, but the low medical visit rate limited statistical significance. This study uses Taiwan's comprehensive NHI program to address this limitation and provides a more robust dataset for evaluating the association between dietary quality and medical resource utilization in preschoolers.

This study utilized data from the 2013–2016 Nutrition and Health Survey in Taiwan (NAHSIT), employing a multistage, stratified, clustered probability sampling method. 614 preschoolers (2–6 years) with 24-h dietary recall data were included, with their data linked to the 2013–2018 National Health Insurance Research Database (NHIRD) using scrambled IDs to assess medical service utilization. Dietary intake was evaluated using the Taiwanese Children Healthy Eating Index (TCHEI), developed based on Taiwanese Food-Based Dietary Guidelines (TFBDG), assessing dietary adequacy and behavior. The TCHEI incorporated six food groups (grains, soy/fish/eggs/meat, dairy, vegetables, fruits, oils/nuts) and dietary behaviors (breakfast frequency, sugar-sweetened beverage consumption, fried food, snack/biscuit intake, seasoning use). Medical service utilization included overall, outpatient, and emergency visits, categorized for all diseases and respiratory diseases (using ICD-9 and ICD-10 codes). Annual medical expenditures were adjusted for inflation. Covariates included age, sex, region, mother's education, family financial status, and total energy intake. Statistical analysis used multivariable generalized linear models (Poisson distribution for counts, gamma distribution for expenditures), adjusting for confounders. Age stratification (2–3 years and 4–6 years) was used to analyze the data, and all analyses were conducted unweighted due to the data's unique characteristics.

Children aged 2–3 years in the higher TCHEI tertiles (T2 and T3) exhibited significantly lower overall medical visits (25% and 16% reduction, respectively) compared to the lowest tertile (T1). This pattern was consistent for outpatient and emergency visits, both for all diseases and respiratory diseases. In children aged 4–6 years, the T2 group showed a 15% reduction in overall visits and an 11% reduction in respiratory disease visits. Across all ages, the T2 group showed lower overall medical expenditures than the T1 group. Higher TCHEI scores were significantly associated with higher intake of protein, polyunsaturated fatty acids, dietary fiber, vitamin C, vitamin B6, potassium, calcium, magnesium, and iron, while saturated fatty acid intake showed a non-significant trend towards lower intake in the T3 group compared to the T1 group. Sensitivity analyses excluding accidental injuries and participants with congenital conditions generally supported the primary findings, though the association between TCHEI and all-disease expenditure in the 2-3-year-old group became non-significant when congenital conditions were excluded. Children with higher TCHEI scores tended to have mothers with higher education levels and better household financial status.

The findings strongly support the association between optimal dietary intake, as measured by the TCHEI, and reduced medical service utilization and expenditure in Taiwanese preschoolers, particularly those aged 2–3 years. This suggests that promoting adherence to dietary guidelines could lead to considerable cost savings in healthcare, while potentially improving overall child health. The association between higher TCHEI scores and better nutritional status (higher intake of essential nutrients) further solidifies the importance of a healthy diet during early childhood. The observed differences based on age may be attributed to the less robust immune system of younger children, leading to higher medical service utilization. The influence of socioeconomic factors (maternal education and family financial status) is also noteworthy, highlighting the complex interplay between diet, health, and socio-economic conditions. While the study controlled for these factors, residual confounding remains a possibility.

This study demonstrates a significant association between adherence to dietary guidelines, as measured by the TCHEI, and reduced medical service utilization and expenditure in Taiwanese preschoolers. The findings highlight the importance of promoting healthy dietary habits in early childhood to improve overall health and reduce healthcare costs. Future research could explore the long-term effects of early childhood dietary patterns on health outcomes, potentially extending the follow-up period to assess adult health. Further research should also investigate culturally sensitive and cost-effective interventions to improve dietary intake amongst economically disadvantaged families.

The study's limitations include the use of a single 24-h dietary recall, which may not fully capture usual dietary intake. The TCHEI, while validated, is specific to Taiwan and may not be generalizable to other populations. Moreover, the study did not include data on physical activity, living environment, or psychological stress, which may influence health outcomes. The association between socioeconomic factors and dietary quality suggests a need for further investigation into the influence of these factors on health and healthcare utilization.