Evaluation of 25-hydroxyvitamin D levels in obese individuals

Aims: Although 25-hydroxyvitamin D [25(OH)D] deficiency is common, only a few studies have focused on the 25(OH)D level in obese people in Turkey. Therefore, this study assessed the relationship between 25(OH)D status and obesity in the Kayseri region in Turkey. Methods: This cross-sectional study included otherwise healthy individuals aged 20 to 49 years. Obesity was defined as body mass index (BMI) ?30. A bioelectrical impedance analyzer was used to measure the body composition. The short form of the “International Physical Activity Questionnaire” was used to assess the physical activity level. Blood 25(OH)D and parathyroid hormone (PTH) levels, dietary intake, body composition, and potential factors associated with the 25(OH)D status were determined. Results: The study included 268 adults (mean age: 31.4±9.5 years, 69.5% were women). The proportion of vitamin D deficiency (<20 ng/mL) was 84.3% and 83.5% in the obese and normalweight individuals, respectively. Obese individuals had lower 25(OH)D level [11.6 (8.1-17.9) vs. 13.5 (9.7-18.3) ng/mL, p=0.069] and higher PTH level [44 (35.0-63.0) vs. 36 (28.0-47.0) pg/mL, p<0.001] compared with their normal-weight counterparts. Dietary vitamin D and calcium intake were similar, whereas phosphorous intake was higher in the obese subjects [1052.7 (754.9-1118.4) vs. 945.7 (754.9-1118.4) mg/day p=0.015]. 25(OH)D levels correlated with BMI (p<0.001, r=-0.170), body fat mass (p<0.01, r=-0.179), and muscle mass (p<0.001, r=0.251). Conclusions: 25(OH)D deficiency is common among obese and normal-weight individuals in this large middle Anatolian city of Turkey. This study found a relationship between serum 25(OH)D levels and BMI, body fat, and muscle mass in the study sample. © 2022. by the University of Health Sciences Turkey, Gülhane Faculty of Medicine / Gülhane Medical Journal published by Galenos Publishing House