Relationship between 25-Hydroxy Vitamin-D and Obesity in 2-7 years old Children Referred to a Paediatric Hospital in Iran.

BACKGROUND Obesity is increasing in children and it can cause many complications in adulthood, such as Diabetes mellitus (DM) and metabolic syndrome. In observational studies, vitamin-D was one of the factors which were found to be associated with obesity. AIMS To determine the association between body mass index (BMI) and serum level of vitamin-D in children who were outpatients at Taleghani Paediatric Hospital, Iran. SETTINGS AND DESIGN This was a cross-sectional observational study done on 215 children who were 2 to 7 y old, who were referred to Taleghani Hospital in winter (1391 solar calendar) 2013. MATERIALS AND METHODS In this cross-sectional study, anthropometric indices: weight, height and waist circumference were measured by using identical instruments. BMI was also determined as per CDC 2000 criteria. Vitamin-D levels were estimated by ELISA. STATISTICAL ANALYSIS Vitamin-D levels which were less than 20 nmol/L were considered as a deficiency, levels which were 20-30 nmol\L were considered as inadequate and those which were equal to or greater than 30 nmol\L were considered as sufficient. t-test, ANOVA and Pearson's correlation coefficient at a significant level of 0.05 were applied and data were analysed by using SPSS (version 16). RESULTS One hundred and twenty five children (47.4%) were males and the rest were females. One hundred eighty four children (85.6%) had vitamin-D deficiency and only 31 had adequate levels of vitamin-D. The prevalence of obesity and overweight were 27%, but considering the vitamin-D status, it was found to be insignificant. However, there was a linear relationship between waist circumference and serum vitamin-D (p<0.01). The means and standard deviations of serum vitamin-D levels in girls and boys were 22.76 ±11.62 and 23.46 ± 9.30 nmol/L and this difference was not significant. Vitamin-D levels found in the three ethnic groups of Fars, Turkmen and Sistani showed significant differences (p<0.002). CONCLUSIONS There was a high prevalence of vitamin-D deficiency in 2 to 7 year olds. There was no significant relationship between BMI and vitamin-D, but it was recorded in ethnic groups, and there was a correlation between waist circumference and vitamin-D levels. More exposure to sunlight and prescription of vitamin supplements were recommended.