Vitamin D Status, Latitude and their Associations with Some Health Parameters in Children: National Food and Nutrition Surveillance.
Recent data indicate a role for vitamin D in many health aspects including anthropometric measures and blood lipid profiles. Dermal vitamin D synthesis may be influenced by latitude. However, the contribution of latitude in vitamin D status and its association with anthropometric and blood lipid measures in Iranian children have not been studied to date.



We used data from the National Food and Nutritional Surveillance Program. In total, 667 apparently healthy children aged 5-18 years were randomly selected from six provinces of Iran with different latitudes, from 29 to 37°. Weight, height, circulating 25-hydroxycalciferol; calcidiol [25(OH)D] and blood lipids were measured.



In total, 16.7 and 4.1% of children were overweight or obese, respectively. The mean 25(OH)D concentration was 27.3 ± 17.6 nmol/l (95% confidence interval: 26.0-28.7 nmol/l). Over 93% of all children had suboptimal circulating calcidiol concentrations. Undesirable status of vitamin D, serum triglyceride and low-density lipoprotein were all more prevalent in children living in regions  >33° latitude than those in  <33°, significantly. There was no significant difference in duration of sun exposure between children living in latitudes below and above 33° (p = 0.093). In multivariate regression model, sex, latitude, body mass index for age z-score and sun exposure duration were independently related to 25(OH)D concentrations, but age was not.



Despite significant association of latitude and vitamin D status, hypovitaminosis D is prevalent across latitude gradient in Iranian children. Our findings warrant immediate sustainable nutritional intervention, including supplementation, to protect children from hypovitaminosis D irrespective of the latitude of their residence.
Laboratory of Nutrition Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran 1981619573, Iran.
Bahareh
B
Nikooyeh
Nutrition Office, Iran Ministry of Health, Treatment and Medical Education, Tehran 1467664961, Iran.
Zahra
Z
Abdollahi
Department of Nutritional Policy-Making Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran 1981619573, Iran.
Majid
M
Hajifaraji
Department of Biostatistics, Shahid Beheshti University of Medical Sciences, Tehran 1971653313, Iran.
Hamid
H
Alavi-Majd
Nutrition Office, Iran Ministry of Health, Treatment and Medical Education, Tehran 1467664961, Iran.
Forouzan
F
Salehi
UNICEF Office, Tehran 193951176, Iran.
Amir Hossein
AH
Yarparvar
Laboratory of Nutrition Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran 1981619573, Iran neytr@yahoo.com tneyestani@nnftri.ac.ir.
Tirang R
TR
Neyestani
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006306:Health Surveys; D006801:Humans; D007492:Iran / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D009752:Nutritional Status; D015995:Prevalence; D012111:Residence Characteristics; D012307:Risk Factors; D013472:Sunlight; D014808:Vitamin D Deficiency / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*
anthropometry; children; latitude; lipid profile.; vitamin D