Vitamin D is a fat-soluble vitamin that plays a crucial role in calcium and phosphate metabolism, directly influencing bone health and growth in children. Beyond its well-established function in the skeletal system, vitamin D also affects various non-skeletal physiological processes, including immune function, cellular differentiation, and the modulation of inflammation. Despite its importance, vitamin D deficiency remains a widespread public health issue, especially in developing countries, including India.

The primary source of vitamin D is sunlight, specifically ultraviolet B (UVB) rays, which facilitate the synthesis of vitamin D3 (cholecalciferol) in the skin. However, factors such as limited sunlight exposure, air pollution, the use of sunscreen, and clothing habits in many parts of the world, including India, contribute to insufficient vitamin D levels. Additionally, dietary sources of vitamin D, such as fortified foods, dairy products, and fatty fish, are often limited in the typical diet of children in low-income populations, exacerbating the deficiency.

Vitamin D deficiency in children is particularly concerning due to its association with several health conditions, including rickets, osteomalacia, and delayed growth and development. Rickets, a condition characterized by the softening and weakening of bones in children, is one of the most severe consequences of vitamin D deficiency. In addition to skeletal abnormalities, insufficient vitamin D levels have been linked to impaired muscle function, increased susceptibility to infections, and potential cognitive delays. Inadequate vitamin D may also contribute to the development of chronic diseases later in life, such as osteoporosis, cardiovascular disease, and metabolic disorders.

In India, the prevalence of vitamin D deficiency among children has reached alarming proportions, with studies indicating that up to 80% of children may have suboptimal vitamin D levels, especially in rural and low socioeconomic communities. This is largely attributed to inadequate dietary intake, reduced sunlight exposure due to the geographical location, and socio-cultural practices such as the early use of coverings and limited outdoor activities. Malnutrition, which is prevalent in many parts of India, also worsens the deficiency, as children often lack foods that are rich in vitamin D and calcium.

One of the critical periods of growth and development in children is from birth to five years, as this is the time when physical and cognitive development occurs at the fastest rate. Growth parameters such as height, weight, and head circumference are key indicators of a child’s overall nutritional and health status. These parameters are influenced not only by genetic factors but also by nutritional intake and the presence of micronutrient deficiencies. Vitamin D plays a pivotal role in this phase by facilitating the absorption of calcium and phosphorus, which are essential for bone growth, thus influencing the child’s height and weight. Recent studies have suggested a link between low vitamin D levels and stunted growth, underweight status, and delayed development in children.

The World Health Organization (WHO) recommends that children receive adequate levels of vitamin D to ensure optimal bone health and prevent growth disorders. However, there is still a significant gap in the availability of data from specific regions in India that investigate the relationship between vitamin D status and growth parameters in children, particularly in rural and semi-urban populations like those in Saharanpur, Uttar Pradesh.

This study aims to bridge this gap by evaluating serum vitamin D levels and their association with growth parameters (height, weight, and head circumference) in children under 5 years of age attending the pediatric outpatient department or admitted at Ul-Hind Maulana Mahmood Hasan (SMMH) Government Medical College in Saharanpur. This will be the first step in identifying the extent of vitamin D deficiency in this demographic and its potential impact on child health. Furthermore, understanding the socio-economic and environmental factors that contribute to vitamin D deficiency in this region will aid in formulating effective public health strategies to address this issue.

Thus, the primary objectives of this study are to assess the serum vitamin D levels in children under 5 years of age and to explore the relationship between vitamin D status and growth parameters, which will help inform future interventions targeting this important nutritional deficiency.

This was a prospective observational study conducted from September 2024 to February 2025 at Ul-Hind Maulana Mahmood Hasan (SMMH) Government Medical College, Saharanpur, Uttar Pradesh, India. The study aimed to evaluate the serum vitamin D levels and their association with growth parameters in children under the age of five. Ethical approval was obtained from the Institutional Ethics Committee of the medical college, and informed consent was acquired from the parents or guardians of the children enrolled in the study.

The study included 200 children aged between 6 months and 5 years who were either attending the pediatric outpatient department or admitted to the hospital wards. Children with chronic diseases known to affect bone metabolism, such as nephrotic syndrome, rickets, or osteomalacia, as well as those currently receiving vitamin D supplements or other medications influencing vitamin D levels, were excluded from the study. Similarly, children who were acutely ill during the study period were not enrolled to avoid confounding factors.

A structured questionnaire was used to collect demographic data, including age, sex, and socioeconomic status, as well as dietary habits, sun exposure, and family history of vitamin D deficiency. Growth parameters, including height, weight, and head circumference, were measured by trained pediatricians using calibrated instruments. Height was measured using a stadiometer, weight with an electronic weighing scale, and head circumference with a flexible measuring tape, all adhering to standard pediatric measurement protocols. The growth parameters were compared to WHO growth standards, with the 5th and 85th percentiles used to categorize children as underweight, stunted, or overweight.

Blood samples were collected from each child for analysis of serum 25-hydroxyvitamin D (25(OH)D) levels, which is considered the best marker of vitamin D status. Blood samples were drawn in the morning hours and processed in the hospital's central laboratory. Serum 25(OH)D levels were quantified using high-performance liquid chromatography (HPLC), and vitamin D deficiency was defined as a serum 25(OH)D concentration of less than 20 ng/mL, insufficiency as 20–30 ng/mL, and sufficiency as above 30 ng/mL.

Statistical analysis was performed using SPSS version 25. Descriptive statistics were used to summarize demographic characteristics, serum vitamin D levels, and growth parameters. For correlation analysis, Pearson’s or Spearman’s rank correlation tests were employed, depending on the distribution of the data, to evaluate the relationship between serum vitamin D levels and growth parameters (height, weight, and head circumference). A p-value of less than 0.05 was considered statistically significant.

This methodology allowed for a comprehensive analysis of the vitamin D status and growth metrics in the study cohort, providing valuable insights into the nutritional challenges faced by children under five in this region.

A total of 200 children under the age of 5 years were enrolled in the study, with a mean age of 2.5 ± 1.2 years. Of these, 52% were male and 48% were female. The majority of the children (75%) resided in rural areas, and 60% came from lower-middle-class families. The study aimed to assess the vitamin D status of these children and its association with their growth parameters, including height, weight, and head circumference. The findings revealed a concerning prevalence of vitamin D deficiency, with a significant proportion of children exhibiting suboptimal serum vitamin D levels. Furthermore, the data indicated clear associations between vitamin D levels and the children's growth metrics, providing critical insights into the impact of vitamin D deficiency on early childhood development in this region.

Demographic Profile

The following table presents the demographic characteristics of the study participants:

Serum Vitamin D Levels

The distribution of serum vitamin D levels in children is as follows:

Growth Parameters

The following tables display the growth parameters of the children:

Height Distribution

Weight Distribution

Head Circumference Distribution

Correlation between Vitamin D Levels and Growth Parameters

The table below summarizes the correlation between serum vitamin D levels and various growth parameters:

Risk Factors for Vitamin D Deficiency

The table below summarizes the risk factors associated with vitamin D deficiency in the study population:

Vitamin D deficiency is a well-recognized public health concern, particularly in children, as it directly impacts bone health and has broader implications for overall growth and development. In this study, we assessed the serum vitamin D levels and growth parameters (height, weight, and head circumference) in children under 5 years of age attending Ul-Hind Maulana Mahmood Hasan (SMMH) Government Medical College in Saharanpur, Uttar Pradesh, India. Our findings indicate a high prevalence of vitamin D deficiency among children, with 30% of children having deficient levels (serum 25(OH)D < 20 ng/mL) and an additional 40% having insufficient levels (serum 25(OH)D 20–30 ng/mL). These results are consistent with previous studies conducted across various regions of India and other developing countries.

Vitamin D Deficiency and Its Prevalence

In our study, 70% of children had either deficient or insufficient levels of vitamin D, highlighting the widespread nature of this deficiency. This is in line with findings from other studies in India, which have reported a high prevalence of vitamin D deficiency, ranging from 50% to 90%, particularly in children under 5 years. For instance, a study conducted by Ghosh et al. (2018) in Kolkata found that nearly 80% of children had serum 25(OH)D levels below 30 ng/mL. Similarly, in a study conducted in Delhi, Choudhary et al. (2020) reported that 72% of children had insufficient or deficient levels of vitamin D.

The high prevalence in our study can be attributed to several factors commonly seen in the Indian context. Firstly, reduced sunlight exposure, particularly in rural areas, significantly limits the synthesis of vitamin D in the skin. The geographical location of Uttar Pradesh, along with cultural practices such as limited outdoor activities and the use of coverings, likely contributed to this deficiency. Secondly, the lack of dietary sources of vitamin D, particularly in low-income families, further exacerbates the issue. While fortified foods like milk and cereals are available, they are often inaccessible or unaffordable to families in rural or economically disadvantaged regions.

Vitamin D and Growth Parameters

Our study found a significant positive correlation between serum vitamin D levels and growth parameters, such as height, weight, and head circumference. Children with sufficient vitamin D levels exhibited better growth outcomes compared to those with insufficient or deficient levels. This finding aligns with existing literature that has demonstrated the critical role of vitamin D in bone mineralization and overall growth.

For example, a study by Sachdev et al. (2019) reported that vitamin D deficiency in children was associated with stunted growth and lower weight in the first five years of life. Similarly, a study conducted by Agarwal et al. (2017) found a significant relationship between low vitamin D levels and underweight status in Indian children. Our findings are also supported by a meta-analysis by Wu et al. (2021), which concluded that vitamin D deficiency in early childhood is linked to an increased risk of impaired linear growth and delayed physical development. This underscores the importance of adequate vitamin D for skeletal and overall growth during the critical developmental years.

The relationship between vitamin D levels and head circumference, a marker of brain growth, was also observed in our study, with children having sufficient vitamin D showing better head circumference measurements. This finding is particularly relevant as it suggests that vitamin D may play a role not only in physical growth but also in neurological development. A similar observation was made in a study by Bener et al. (2018), which showed a positive association between vitamin D levels and head circumference growth in young children.

Risk Factors for Vitamin D Deficiency

Our study identified several key risk factors for vitamin D deficiency, including exclusive breastfeeding, limited sunlight exposure, and low socioeconomic status. A significant number of children in the study were exclusively breastfed, and while breast milk provides essential nutrients, it is a poor source of vitamin D unless the mother is vitamin D sufficient or supplements are given. This is consistent with findings from several studies, including a study by Gupta et al. (2017), which found that exclusive breastfeeding without supplementation was a major risk factor for vitamin D deficiency in infants.

Limited sunlight exposure is another critical factor contributing to vitamin D deficiency in our study. The geographical location of Saharanpur, with its relatively low sunlight exposure during the winter months, coupled with a culture that often limits outdoor activity for children, likely plays a significant role in the observed deficiency. A study by Thorne et al. (2019) also highlighted that children living in urban areas with high pollution and limited outdoor play have significantly lower levels of vitamin D. In contrast, children with more exposure to sunlight, especially in the morning hours, tend to have better vitamin D status.

Socioeconomic status, which was another significant risk factor identified in our study, has been well-documented as a determinant of vitamin D deficiency. Lower-income families may have limited access to nutritious foods that are rich in vitamin D, such as fortified dairy products, fish, and eggs. A study by Saha et al. (2020) in rural West Bengal also found a high prevalence of vitamin D deficiency in children from low-income families, with insufficient dietary intake and inadequate healthcare access as contributing factors.

Public Health Implications and Recommendations

The findings of this study underscore the urgent need for public health interventions to address vitamin D deficiency in children, particularly in rural areas like Saharanpur. Vitamin D supplementation programs for children, along with public awareness campaigns on the importance of sunlight exposure and dietary sources of vitamin D, should be prioritized. The Government of India has already recognized the need for vitamin D fortification of staple foods, and this could be an effective strategy to address the deficiency at a population level, particularly for children under five.

Additionally, promoting outdoor physical activity, particularly in the morning hours when sunlight is less intense, can be a practical approach to improving vitamin D status in children. Since many children in India spend a significant amount of time indoors due to environmental and cultural factors, encouraging outdoor play could have significant benefits for their overall health.

Limitations and Future Research

While this study provides important insights into the relationship between vitamin D and growth parameters, it has some limitations. The study was conducted at a single center in Saharanpur, and thus, the results may not be generalizable to other regions with different environmental and socioeconomic conditions. Furthermore, we did not measure serum calcium and phosphorus levels, which are also important in bone health and may offer additional insights into the relationship between vitamin D and skeletal growth. Future studies with larger sample sizes, multi-center data, and longitudinal designs could provide more comprehensive information on the long-term effects of vitamin D deficiency on child health.

This study highlights the high prevalence of vitamin D deficiency in children under 5 years of age in Saharanpur, UP, and its significant association with impaired growth parameters. Our findings support the growing body of evidence indicating that adequate vitamin D is crucial for optimal growth and development in early childhood. Efforts to improve vitamin D status through supplementation, dietary interventions, and increased sunlight exposure are essential to promote better health outcomes in Indian children.

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