Bahareh Nikooyeh1, Zahra Abdollahi2, Majid Hajifaraji3, Hamid Alavi-Majd2, Forouzan Salehi4, Amir Hossein Yarparvar5, Tirang R Neyestani1. 1. 1Laboratory of Nutrition Research,National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology,Shahid Beheshti University of Medical Sciences,PO Box 19395-4741, Tehran,Islamic Republic of Iran. 2. 2Department of Biostatistics,Shahid Beheshti University of Medical Sciences,Tehran,Islamic Republic of Iran. 3. 3Department of Nutritional Policy-Making Research,National Nutrition and Food Technology Research Instituteand Faculty of Nutrition Sciences and Food Technology,Shahid Beheshti University of Medical Sciences,Tehran,Islamic Republic of Iran. 4. 4Nutrition Office,Iran Ministry of Health,Treatment and Medical Education,Tehran,Islamic Republic of Iran. 5. 5UNICEF Office,Tehran,Islamic Republic of Iran.
Abstract
OBJECTIVE: To investigate seasonal variations of vitamin D status at different latitudes and if these changes are accompanied by corresponding variations in certain health parameters in children living in a broad latitudinal range in Iran. DESIGN: Longitudinal study. SUBJECTS: In total, 530 apparently healthy children aged 5-18 years were randomly selected from six regions of Iran with a latitudinal gradient from 29°N to 37·5°N. All anthropometric and biochemical assessments were performed twice during a year (summer, winter). High BMI (Z-score >1), low HDL cholesterol (150 mg/dl) were considered cardiometabolic risk factors. RESULTS: Serum 25-hydroxyvitamin D (25(OH)D) showed between-season variation, with significantly higher concentrations (mean (sd)) in summer v. winter (43 (29) v. 27 (18) nmol/l; P33°N v. <33°N: 4·5; 0·09, 9·0; P=0·04) were predictors of change of serum 25(OH)D between two seasons. CONCLUSIONS: Summertime improvement of vitamin D status was accompanied by certain improved cardiometabolic risk factors, notably serum TAG, total cholesterol and BMI, in children.
OBJECTIVE: To investigate seasonal variations of vitamin D status at different latitudes and if these changes are accompanied by corresponding variations in certain health parameters in children living in a broad latitudinal range in Iran. DESIGN: Longitudinal study. SUBJECTS: In total, 530 apparently healthy children aged 5-18 years were randomly selected from six regions of Iran with a latitudinal gradient from 29°N to 37·5°N. All anthropometric and biochemical assessments were performed twice during a year (summer, winter). High BMI (Z-score >1), low HDL cholesterol (150 mg/dl) were considered cardiometabolic risk factors. RESULTS: Serum 25-hydroxyvitamin D (25(OH)D) showed between-season variation, with significantly higher concentrations (mean (sd)) in summer v. winter (43 (29) v. 27 (18) nmol/l; P33°N v. <33°N: 4·5; 0·09, 9·0; P=0·04) were predictors of change of serum 25(OH)D between two seasons. CONCLUSIONS: Summertime improvement of vitamin D status was accompanied by certain improved cardiometabolic risk factors, notably serum TAG, total cholesterol and BMI, in children.
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Keywords:
Cardiometabolic risk factors; Seasonal variation; Vitamin D