Bahareh Nikooyeh1, Zahra Abdollahi2, Majid Hajifaraji3, Hamid Alavi-Majd4, Forouzan Salehi2, Amir Hossein Yarparvar5, Tirang R Neyestani6. 1. 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. 2. Nutrition Office, Iran Ministry of Health, Treatment and Medical Education, Tehran 1467664961, Iran. 3. 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. 4. Department of Biostatistics, Shahid Beheshti University of Medical Sciences, Tehran 1971653313, Iran. 5. UNICEF Office, Tehran 193951176, Iran. 6. 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.
Abstract
BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.