Sultan , MBBS – Raghda A Sultan , MBBS
– Areej O Mahjoub , MBBS – Abdulmoein E Al-Agha , FRCPCH
D is also known as Calcitriol or 1, 25-Dihydroxycholecalciferol. Vitamin D has
significant role in different physiological systems of human body. It has many
major roles in human body including normal growth. Vitamin D is mainly
considered for its role associated with the health of bones, teeth, and
cartilages as well as calcium absorption, but Vitamin D is also essential for
other mental and developmental functions. Vitamin D deficiency is one of the
major public health problem for all age groups worldwide 1. Vitamin D
deficiency is significantly more prevalent in obese children. In recent years,
the prevalence of obesity has increased, and now it is significantly one of the
major global public health problem 2. Vitamin D is one of the essential
components which needs to be included in the daily diet. It is essential for
activity and proper development of physiological systems of the human body.
Vitamin D causes many health issues and diseases associated with the physical
development, brain, thyroid glands, bones, teeth, and heart.
is one of the vital components to be included in the diet on daily basis. It
strengthens the bones and help in growth and developing by maintaining many
physiological and biochemical processes. Vitamin D is also important for the
absorption of calcium. It has been observed that calcium absorption is also
compromised in case of vitamin D deficiency. There are multiple health related
issues, which are associated with vitamin D deficiency. Vitamin D deficiency
can also compromise growth and development and may lead to short stature. The
term “short stature” is referred to two or more standard deviations of human
body below the average height for the appropriate age, gender, and race 3.
et al. stated that there is functional association of vitamin D with brain and
many neurological activities 4. Vitamin D is one of the fat-soluble vitamins
and can be synthesized and bioactivated in the human body with sun exposure.
The rich sources of vitamin D are fish, eggs, fortified milk, and cod liver oil
5. Obesity is defined as a body mass index (BMI) greater than the 95th
percentile for age and gender 6. Although, deficiency of vitamin D has
remained as a major public health issue, but there are not enough studies
conducted on vitamin D deficiency among Saudian children.
Aim & Objectives of Research. The
aim of this study is to investigate the impact of Vitamin D deficiency on
children growth in Jeddah, Saudi Arabia.
main objectives of this research are,
the association between vitamin D deficiency and obesity.
the link of deficiency of vitamin D with weight and height.
out the risk of obesity related to vitamin D deficiency.
Research Questions. This research seeks
the answers of the below mentioned questions;
What is the
relationship between vitamin D deficiency and obesity?
vitamin D deficiency relate to the weight and height?
How can the
obesity be developed due to deficiency of vitamin D?
have no conflict of interest, and the work was not supported or funded by
Significance of the Study. This study
has made a valuable contribution to the previous work achieved on the
evaluation of the relationship between vitamin D deficiency and obesity. This
study could help healthcare professionals while diagnosing causes of obesity in
children. The relation of weight and height with vitamin D deficiency are also
highlighted in the study supporting previous studies conducted in this context.
This study may add a piece of informative work regarding the vitamin D
deficiency in relation with the obesity in children in Saudi Arabia.
Limitations of the Study. This study
cannot be generalized to all the population of the world. The reason is that
this study has taken only children of Saudi Arabia. There are multiple factors
such as environmental and genetic factors that can affect the association of
the vitamin D with the obesity. That is why this study is limited to the
population of Saudi Arabia.
study is based on the cross-sectional study design. Cross-sectional study
design is widely used in the medical researches and studies related to social
sciences. This study design is a type of
observational study which involves the data collection from a population or a
group of population and then data analysis is performed 7. This type of study
design may also include a characteristic subsection to estimated results at a
specific point in time. The main purpose of selecting this study design is to
evaluate descriptive issues. This method is mostly used to investigate and
figure out the association between outcomes and experiences.
In this cross-sectional study, data was collected from 273 randomly
selected healthy children. There were 193 girls and 144 boys aged in between 4
to 13 years. These participants were evaluated in an ambulatory pediatric
clinic in King Abdul-Aziz University Hospital in Jeddah, Saudi Arabia, between
August 2016 and April 2017. A questionnaire was designed to collect information
on self-reported and direct measures of health and wellness. An interview was
held with children and their family, followed by height and weight
measurements. Phlebotomy team took blood samples for measurement of vitamin D,
thyroid and parathyroid hormones, and calcium. Any child with organic disease
(i.e. liver or kidney disease or diabetes mellitus), endocraniopathies,
secondary obesity or secondary short stature, short stature (familial, genetic,
malabsorption), supplementation with vitamin D or calcium, serious intercurrent
illness and data insufficiency were excluded from the study.
Considerations. There are multiple ethical concerns that are
significantly required to be considered while undertaking a study or research.
Informed consent is one of the major ethical considerations while conducting
research. It is regarding the permission, willingness, and understanding of the
participants to take part in the study. It is quite essential that participants
taking part in the research must have information of the purpose, process,
potential benefits and risk related to study, as well as their alternative in
participation in the study. Written and verbal consent were obtained prior to
asking parents to fill in the questionnaire. Ethical approval for this study
was obtained from the Research Ethics Committee at King Abdul-Aziz University
and Height Variables. SDS was calculated for weight and height.
Obesity was defined as weight SDS > 1.6, and short stature was defined as height
SDS < 2. Log transformation was on weight which was measured in kilograms (kg) to transform positive skewed data of weight and to conform the normality at approximately level. Laboratory Tests Vitamin D Measurements. A fasting blood sample was drawn from participants. Vitamin D deficiency is the state of having a 25(OH)D concentration < 50 nmol/L (Lavie et al., 2014). For calcium level, a concentration of 2.2-2.62 mmol/L was considered normal. For evaluation of thyroid function, FT4 was assessed and a concentration of 12-22 pmol/L was taken as normal level. For parathyroid hormone, a concentration of 1.6-6.2 pmol/L was considered normal. Statistical Analysis Data analysis was performed using SPSS Statistics version 16.0 software (IBM Corp., Armonk, NY, USA). SPSS is widely used for analyzing the data collected from a research to interpret the results. Standard descriptive statistics were presented as percentages or mean ± SD. Paired t-test was performed to compare group variables. The Levene test for equality of variances was used to test the normal distribution of variables in the groups. ANOVA was used to analyze the differences among group means and their associated procedures. A value of P < 0.05 was considered statistically significant. Results Relevant characteristics of study group and measured serum levels are reported in table 1. This study group consisted of 193 girls (57.3%) and 144 boys (42.7%). The mean age of the participants was 9.9 ± 3.8 years (95%) with confidence interval (CI), (9.4 to 10.6). The average weight of the participants was 34.6 kg for boys and 33.1 for girls. Mean values for log 10 of weight was same i.e. 1.5 for boys and girls. The average height in 132.3 cm in boys and 132.6 cm in girls. Table 1: Baseline characteristics of study population Age, Body Measurement and Vitamin Males Mean ± SD Females Mean ± SD Age (year) 9.5 ± 3.4 10.3 ± 4.2 Weight (Kg) 34.7 ± 15.5 33.2 ± 14.2 Weight (sds) 1.4 ± 2.3 0.8 ± 1.8 Log10 Weight 1.5 ± 0.2 1.4 ± 0.1 Height (cm) 132.3 ± 17.8 132.6 ± 17.3 Height (sds) -0.01±1.3 -0.1±1.1 BMI (kg/m2) 18.2 ± 3.7 17.7 ± 3.2 BMI (sds) 0.9 ± 1.2 0.6 ± 1.2 Vitamin D 28.5 ± 11.5 25.9 ± 11.01 On the other hand, the P-value is estimates as 0.004, which is less than significance value of 0.05 . It means that there is a significant relation of body weight and Vitamin D for both gender and decrease in Vitamin D level will affect the body weight of both male and female. For height, there was no significant relation with vitamin D with the correlation value of 0.01 . Figure 1: Vitamin D among population of the study Serum level of 25(OH)D concentration < 50 nmol/L is indicative of vitamin D deficiency, the results are shown in Figure 1. Deficiency of vitamin D was identified in 96.7 % of participants, while there were only 3.3% of participants with a normal serum level of 25(OH)D. Mean level of Vitamin D was 27.04 ± 11.3 nmol/L which was 95% (Confidence Interval = 25.7, 28.4). With respect to calcium, thyroid and parathyroid levels, levels of calcium were normal in 91.2% of participants. Levels of FT4 were normal in 84.1% of participants. Levels of parathyroid hormone were normal in 86.1% of participants. Table 2: Relation of Vitamin D with other factors Items P-value Mean ± SD Body Measurements Log10 Weight 0.004 (SD= - 0.23) Height (cm) 0.91 (SD= 0.01) Gender Male 0.06 28.5 ± 11.5 Female 0.06 25.9 ± 11.02 The P-value was 0.913 for the relation of vitamin D and height of the children showing that there is no significant relation between the height and vitamin D. This data is presented in Table 2. Figure 2a and b: Vitamin D relation with height SDS a) b) The relationship between level of vitamin D and weight/ height is shown in Figure 2a and b. The results reported that Log10 weight increases as vitamin D levels decreases. On the other hand, as vitamin D level decreases, no change in height was found. Vitamin D showed significant relation with weight. Low vitamin D levels showed increase in the weight with the correlation value of -0.231 for both genders which means that Vitamin D has weak and negative relationship with the body weight for both gender. Discussion In this study, it has been investigated that there is a strong impact of vitamin D deficiency on children growth. A significant relation was found between vitamin D and weight, which directed toward the fact that low vitamin D levels increase weight and ultimately leads to obesity. There are multiple studies conducted worldwide on this issue to evaluate the relation between vitamin D deficiency and obesity. A study conducted in turkey showed that the prevalence of 25(OH)D deficiency was higher in the overweight and obese groups than in the normal weight groups and demonstrated link between decreased 25(OH)D levels and a high BMI 8. Obesity is also observed in people suffering from vitamin D deficiency. It is suggested by some researches that low level of vitamin D is associated with the development of obesity, in addition to environmental and genetic factors and eating behaviors 9, 10, 11, 12. Obesity has become a major health problem and its association with multiple serious complications including cardiovascular diseases, hypertension, diabetes mellitus which leads to high morbidity and mortality rates, affect the quality of life and cause social discrimination 11, 13, 14. The impact of vitamin D deficiency on developing obesity is still under debate and researches are being conducted to evaluate the critical situation to overcome it 15. The findings of this research revealed the importance of vitamin D and its association with obesity. For explanation of possible causes for the relation of vitamin D and obesity, several theories have been developed. One of them suggested that certain vitamin D receptor (VDR) polymorphisms are associated with obesity 16. Another theory suggested that vitamin D is an essential factor for generation of leptin. Accordingly, depletion of vitamin D can take part in increasing the level of appetite resulting as obesity 17. One of another experiment data has revealed that deficiency of vitamin D has role in increasing the process of lipogenesis by exaggerating the levels of parathyroid hormone facilitating calcium influx in adipocytes 18. These theories and processes are also indicative of the relation of vitamin D and obesity. An inverse association between vitamin D status and obesity was also reported in a study conducted in Kuala Lumpur 19. The results of this research revealed that sub-optimal status of vitamin D are observed in the primary school children with obesity. Additionally, various epidemiological studies have demonstrated that vitamin D deficiency is closely related to obesity and increased risk of type 2 diabetes mellitus 20. The results of an invitro study revealed that vitamin D plays a beneficial role in obesity progression, and that vitamin D deficient diet exacerbates weight gain. Similar results was reported in a preclinical research that high doses of vitamin D provided metabolic benefits such as increased insulin sensitivity and decreased body mass 21. Another randomized clinical trial speculate that vitamin D supplementation may enhance weight reduction 22. A study conducted by Kaseb, Haghighyfard, Salami, and Ghadiri-Anari (2017) revealed different results and reported no significant relationship between vitamin D deficiency and metabolic syndrome 23. Frequency of vitamin D deficiency was 93.2% and the frequency of metabolic syndrome was 36 percent 23. On the other hand, the relationship between vitamin D and height was not significant; low vitamin D level does not lead to short stature. Short stature can be attributed to several factors. One explanation of this can be need of a very low level of vitamin D < 10 ng/ml or 25 nmol/L to develop short stature. In accordance with the study population included in this study, only 107 (42%) had vitamin D levels below 25 nmol/L. Another important factor is calcium, which plays a major role in bone mineral density, and was found to be normal in most of the study subject. In contrast to results of this study, the relation between Vitamin D deficiency and short stature has been observed in a study conducted by Bueno, Czepielewski, and Raimundo (2010) in Brazil 24. This study explored that low vitamin D intake was observed in short-stature children. Conclusion Vitamin D has significant impact on the physical and mental development of the human body. Deficiency of Vitamin D can raise different physiological and neurological issues. Vitamin D deficiency is one of the public health issues at global level. This study has shown a significant effect of low levels of vitamin D (Vitamin D deficiency) on the development of obesity. It is certain that deficiency of vitamin D in childhood may lead to different negative outcomes related to health in later stages of life. In accordance with the results of the study, the link of obesity and vitamin D has been evaluated. It can be stated that obesity and associated vitamin D deficiency are among the risk factors for developing different diseases and disorders in later age so it is required to spread awareness regarding this issue. To prevent the society from this public health issue, it is essential to take care of the health patterns of the children and include vitamin D rich sources in their food. Early prevention and vitamin D supplementation can be helpful in this regards. Exposure to sunlight also impact significantly on the bioactivation and synthesis of vitamin D in human body. It is also essential to conduct more researches by defining more factors such as genetics, ethnicities, and races that can help in determining more accurate results. Many researches are conducted and being conducted but still there is need of more researches to be executed. These health issues must be taken into consideration and all the states and countries worldwide should conduct the study to prevent the children and adults form vitamin D deficiency and its associated risks and complications.