The high prevalence of vitamin D deficiency and insufficiency has been reported in numerous countries and is recognized as a major public health issue worldwide (1). Vitamin D deficiency has been linked to a range of acute and chronic conditions (2), such as rickets, osteomalacia, pre-eclampsia (3), impairments in immune function (4), and metabolic or cardiovascular diseases (5). Additionally, it is closely associated with children’s growth and development (6), infectious diseases, and autism spectrum disorders (7). This deficiency not only affects children’s immediate health but may also have long-term implications for the risk of future diseases in both children and adults, such as autoimmune diseases and cardiovascular diseases and obesity (8). It may even affect the development of children’s cardio-cerebral vascular systems, leading to abnormal psychological and behavioral development in children (9). The standard biomarker for assessing vitamin D nutritional status is the serum level of 25-hydroxyvitamin D (25(OH)D). The classification of vitamin D status—whether deficient, insufficient, sufficient, or excessive—is primarily based on the concentration of 25(OH)D. It is important to note that the optimal 25(OH)D level remains a subject of debate, with varying guidelines and organizations proposing different thresholds for defining vitamin D deficiency (10).

25(OH)D levels below 30, 50, and 75 nmol/L have been associated with median prevalence rates (95% CI) of 15.7% (13.7–17.8), 47.9% (44.9–50.9), and 76.6% (74.0–79.1), respectively, across global participants (11). A study involving 1,006 adolescents from 10 cities in nine geographically diverse European countries found that approximately 27% had 25(OH)D levels between 50 and 75 nmol/L, indicative of vitamin D insufficiency, while 15% exhibited levels below 50 nmol/L, signifying vitamin D deficiency (12). According to the “2015–2017 China National Nutrition and Health Status Monitoring Report,” the rate of serum vitamin D deficiency among children and adolescents aged 6–17 years in China was 18.6% during 2016–2017. A meta-analysis by Na et al. (13) revealed that the prevalence of vitamin D deficiency in Chinese children reached 24.03%, with an insufficiency rate of 28.71%, which increased with age. In rural areas, particularly those that are impoverished, the prevalence of vitamin D deficiency among school-age children significantly exceeds the national average (14). Thus, the current landscape of vitamin D deficiency and insufficiency, especially in rural regions, is critically concerning.

Various factors influence the body’s vitamin D levels, including reduced cutaneous synthesis, impaired absorption, and both acquired and genetic metabolic disorders (15). Dietary intake is a significant determinant of vitamin D status; in Denmark, 25(OH)D3 constitutes 24% of the dietary intake among children aged 4–17 years (16). A strong correlation exists between dietary vitamin D intake and vitamin D status in children (17). In Brazil, findings suggest that dietary protein intake may interact with genetic predispositions, affecting vitamin D levels (18). Jingrong et al. (19) discovered that daily consumption of fish and eggs, with an intake of ≥30 grams, can lower the risk of vitamin D insufficiency. Additionally, a 2-year prospective randomized trial demonstrated that a daily intake of 200 g of milk and 50 grams of eggs significantly improved growth and reduced vitamin D deficiency in children (20). The rise in indoor activities has led to decreased sunlight exposure for vitamin D synthesis (21), underscoring the growing importance of dietary intake for vitamin D nutritional levels. However, the majority of existing studies, which focus on the impact of single nutrients or foods on health, ignoring their complex interactions within the human body, which can influence bioavailability and absorption (22), providing relatively limited explanations for health outcomes.

Guangzhou, a prominent city in South China, is celebrated for its traditional Cantonese cuisine. However, research on the Lingnan dietary pattern and its health outcomes is relatively scarce, particularly among children. Additionally, in rural areas of Guangzhou, the issue of vitamin D deficiency in children is more pronounced due to factors such as economic conditions (23), the extent of nutritional knowledge dissemination, and lifestyle habits. Given that the proportion of urban infants and young children taking vitamin D supplements is significantly higher than that in rural areas, and considering that rural children may not meet the minimum dietary intake and dietary diversity (24), investigating the dietary patterns of children in rural areas is crucial for addressing the problem of vitamin D deficiency. Thus, this study aimed to establish dietary patterns encompassing various dimensions, including food types, nutrient composition, and their interactions. It can comprehensively consider the possible interactions between various foods and nutrients, and may detect the cumulative effects of multiple nutrients, which is more conducive to implementing nutritional interventions and has greater public health significance. The findings provide new insights into childhood micronutrient inadequacy and offers scientific evidence and policy recommendations to improve children’s health outcomes.

The present study showed the prevalence rates of vitamin D deficiency and insufficiency of 13.43 and 46.63%, respectively. The prevalence of vitamin D deficiency exhibits significant geographical variation, with particularly high rates reported in regions such as Asia, the Middle East, and Africa (34). In Asia, a widespread occurrence of infants with vitamin D levels below 30 nmol/L has been documented across several countries (34). For instance, in Turkey, the prevalence in this demographic reaches up to 51%, while in Iran, it escalates to 86%, underscoring the acute issue of vitamin D deficiency among infants and toddlers (34). Compared with other Asian countries, China’s situation is relatively better. A meta-analysis conducted by Na et al. (13) revealed that the prevalence of vitamin D deficiency in Chinese children is 24.03%, with an insufficiency rate of 28.71%, which shows an increasing trend with age. Compared with the results of Na et al.’s study, the findings of the present study indicate a significantly lower prevalence of vitamin D deficiency but a considerably higher prevalence of insufficiency than the national average. This suggests that, while the situation regarding vitamin D deficiency among school-age children has improved with ongoing socio-economic development (35), concerns remain significant.

This study employed dietary patterns to evaluate the nutritional status of children, offering a more holistic assessment that considers the complex interrelations among various dietary elements and nutrients (22). Three distinct dietary patterns were identified: a fruits and vegetables pattern, high-protein pattern, and snack pattern. These patterns provide a comprehensive framework for analyzing the nutritional intake of school-age children. The cumulative contribution rates of these three patterns are relatively balanced. Notably, as economic conditions improve, dietary patterns in China are gradually shifting from a traditional focus on fruits and vegetables to one characterized by increased protein intake, particularly from meat (36). Furthermore, the snack pattern, which primarily comprises fast food and convenience items, has emerged as a result of external cultural influences. The dietary patterns identified in this study can serve as critical nutritional guidance for children at risk of vitamin D deficiency.

In this study, multiple linear regression analysis indicated that the fruits and vegetables pattern was negatively correlated with logarithmic vitamin D levels, whereas the high-protein pattern exhibited a positive correlation. SEM corroborated these findings, demonstrating consistency between the two analytical methods and affirming the robustness of the results.

A comprehensive evaluation of the fruits and vegetables dietary pattern reveals several factors contributing to the observed lower levels of vitamin D, warranting careful consideration. First, despite including items such as certain seafood with relatively high vitamin D content, the overall intake remains low, as the primary constituents of this pattern are still predominantly fruits and vegetables. This reliance results in limited direct sources of vitamin D. Second, dietary fiber—particularly the insoluble variety abundant in fruits and vegetables—can increase intestinal content volume (37). This increase may lead to nutrient binding, including vitamin D, potentially reducing its solubility and absorption (38). Moreover, the relatively low fat intake associated with this dietary pattern could directly impede the solubility and absorption efficiency of vitamin D, as concurrent lipid co-transport is essential in the intestinal milieu. Lastly, the impact of dietary fiber extends beyond its direct effects; it is known to influence the metabolism and absorption of cholesterol and lipids (39), which, in turn, can indirectly affect vitamin D absorption by altering the lipid environment within the digestive tract. This indirect mechanism may further contribute to the reduced bioavailability of vitamin D. In summary, the dietary pattern’s reliance on fruits and vegetables, coupled with high dietary fiber and low fat intake, presents a multifaceted challenge for vitamin D absorption. This is in line with the findings of Neufingerl and Eilander (40), who observed that vitamin D intake associated with plant-based diets is typically inadequate, likely due to the limited number of foods naturally rich in vitamin D among fruits and vegetables (41).

By contrast, while cereals and tubers contribute significantly, the high protein dietary pattern is overwhelmingly dominant. A significant positive correlation exists between adherence to this pattern and vitamin D levels in the body, indicating that individuals who follow a high protein dietary regimen tend to have higher vitamin D levels. This finding can be reasonably attributed to the abundance of vitamin D3 sources within this dietary pattern. Specifically, it encompasses a variety of foods rich in vitamin D3, such as red meat, egg yolk, liver, and dairy products. Fish, particularly liver, contains the highest levels of vitamin D, followed by offal, which also provides substantial amounts of vitamin D (42, 43). Egg yolk ranks next, while red meat and meat products typically contain lower amounts. A common characteristic of these foods is their rich vitamin D3 content, alongside relatively high lipid levels. Given the fat-soluble nature of vitamin D, a high-fat environment enhances its dissolution and absorption in the intestine, thereby improving its bioavailability. The findings of this study align with existing literature, further reinforcing the positive correlation between this dietary pattern and vitamin D levels. For instance, a study in Taiwan has clearly indicated a link between adequate red meat consumption and a lower rate of vitamin D deficiency (44). This observation reflects the high protein pattern’s richness in red meat. Additionally, Polzonetti et al. (45) have highlighted the importance of whole milk, cheddar cheese, yogurt, butter, egg yolk, and certain mushrooms as significant dietary sources of vitamin D, all of which hold a prominent place in the high protein dietary pattern.

The gender-stratified analysis revealed a consistent decline in vitamin D levels among individuals adopting a fruits and vegetables dietary pattern, regardless of gender. This observation suggests that the high dietary fiber and phosphate content in fruits and vegetables may inhibit vitamin D absorption, indicating a potential universality in the mechanisms of action of these bioactive substances across genders. Further analysis showed that the high-protein dietary pattern exerts a protective effect solely in girls, likely due to the following reasons. Firstly, girls tend to engage in fewer outdoor activities compared to boys, which may reduce (46) their opportunities for sunlight exposure and subsequent vitamin D synthesis through ultraviolet radiation. Given the limited endogenous pathways for vitamin D synthesis, dietary components become particularly crucial for regulating vitamin D levels in girls. Secondly, studies have indicated that female intake of high-protein foods, particularly dairy products (47), is higher than that of males. This dietary preference suggests that girls may have a higher intake of vitamin D from food sources compared to boys, thereby potentially elevating their serum vitamin D levels. Thirdly, females generally have a higher body fat percentage than males (47). Given that vitamin D is a fat-soluble vitamin, the body composition of girls may facilitate better absorption and storage of vitamin D, enhancing the benefits of a high-protein diet that is rich in this nutrient (48). Lastly, the intricate role of sex hormones in vitamin D homeostasis can be considered. A negative correlation exists between estrogen levels and vitamin D status (49), while testosterone levels are positively associated with vitamin D concentrations (50). This hormone-dependent regulatory mechanism may amplify the influence of dietary patterns on vitamin D levels in girls, rendering the effects of nutritional interventions, such as high protein intake, more pronounced.

Hence, there is a need to place increased emphasis on health education for school-age children, offering scientific guidance in terms of dietary structure, quality, and habits. This approach can enhance the understanding of students, parents, and educational institutions regarding the importance of proper nutrition and balanced diets, modify unhealthy dietary behaviors, and encourage outdoor activities, all of which contribute to the healthy development of school-age children. In the case of school-age children from impoverished regions, taking into account the costs and benefits of interventions, the implementation of nutritional supplement programs may be considered as a feasible strategy to improve their nutritional status.

To the best of our knowledge, this study is the first to assess the effect of dietary patterns on vitamin D levels in school-age children, which is one of the most important indoor factors affecting vitamin D levels. The study has several strengths, the most important of which is its rigorous methodology and quality control. This study performed multi-stage cluster random sampling of subjects and multi-step quality control in the field data collection process, which enhanced the authenticity and validity of the results. Furthermore, multiple methods such as multiple linear regression, structural equation modeling, and stratified analysis were used to test the stability of the results. However, this study has three main limitations. First, the cross-sectional design of the research precludes the establishment of a clear causal relationship between dietary patterns and vitamin D levels. To validate the association, further longitudinal studies or intervention experiments are necessary. Second, data on lifestyle behaviors and dietary intake were collected through questionnaire surveys, a method that may introduce recall bias and social desirability bias. Finally, the study sample consists of rural children from the Guangzhou area, and the characteristics of this specific population may restrict the generalizability of the findings. When extending these results to other populations, it is crucial to account for the differences among diverse groups.

The relationship between dietary patterns and internal vitamin D levels merits further investigation. This study identified three distinct dietary patterns: the fruits and vegetables pattern, the high-protein pattern, and the snack pattern. Using dietary pattern factor scores for multiple linear regression and constructing structural equation models based on food intake amounts, validation of the results from both aspects makes the results more convincing. Notably, the fruits and vegetables pattern emerged as a risk factor for inadequate internal vitamin D levels. Conversely, among girls, the high-protein pattern functioned as a protective factor. The study findings provide robust scientific evidence and policy recommendations aimed at enhancing children’s health outcomes.