Relationship between 1,25-Dihydroxyvitamin D and Body Composition in Middle-Aged Sedentary Adults: The FIT-AGEING Study

Response to vitamin D replacement therapy in obese children and adolescents with vitamin D deficiency: a randomized controlled trial

OBJECTIVES

Vitamin D deficiency is common in the pediatric group with obesity and is a risk factor for metabolic syndrome. Supplementation of vitamin D may require higher dosing than in normal-weight children. The aim of our study was to investigate the response of supplementation on vitamin D levels and the metabolic profile in youths with obesity.

METHODS

Children and adolescents with obesity (Body mass index >2.3 SDS, age ≤18 years) and hypovitaminosis D (level <20 μg/L) who entered a residential weight-loss program in Belgium, were included during summer. Subjects were randomized: Group 1 received 6,000 IU vitamin D daily for 12 weeks, whereas Group 2 simultaneously participating in the weight-loss program received no supplementation. Differences in vitamin D levels, weight, insulin resistance, lipid patterns, and blood pressure after 12 weeks were assessed.

RESULTS

A total of 42 subjects (12-18 years) with hypovitaminosis D were included, group 1 (n=22) received supplementation after randomization. After 12 weeks, a median increase in vitamin D levels of 28.2 (24.1-33.0) and 6.7 (4.1-8.4) µg/L was observed in group 1 and group 2, respectively (p-value<0.001), resulting in vitamin D sufficiency in 100 and 60% of subjects. No significant differences in weight loss (p-value 0.695), insulin resistance (p-value 0.078), lipid patterns (p-value 0.438), or blood pressure (p-value 0.511) were observed between both groups after 12 weeks of treatment.

CONCLUSIONS

Supplementation with 6,000 IU vitamin D daily during 12 weeks in children and adolescents with obesity and hypovitaminosis D is safe and sufficient to reach vitamin D sufficiency. However, no positive effects on weight loss, insulin resistance, lipid patterns, or blood pressure were observed.

1,25-Dihydroxyvitamin D and S-Klotho Plasma Levels: The Relationship Between Two Renal Antiaging Biomarkers Mediated by Bone Mineral Density in Middle-Aged Sedentary Adults

The main active metabolite of vitamin D, the 1,25-dihydroxyvitamin D (1,25(OH)₂D), and the shed form of the α-Klotho gene (S-Klotho) play an important role in aging-related physiological processes and are currently considered powerful antiaging renal biomarkers. We aimed to investigate the relationship between 1,25(OH)₂D and S-Klotho plasma levels in middle-aged sedentary healthy adults. We also aimed to study the mediation role of body composition, physical activity levels, dietary parameters, and blood markers in the association between 1,25(OH)₂D and S-Klotho plasma levels. A total of 73 middle-aged sedentary adults (53.4% women; 53.7 ± 5.1 years old) were enrolled in this cross-sectional study. The 1,25(OH)₂D plasma levels were measured using a DiaSorin Liaison^® immunochemiluminometric analyzer. S-Klotho plasma levels were measured using a solid-phase sandwich enzyme-linked immunosorbent assay. Body composition analysis was performed using dual-energy X-ray absorptiometry scanner. A tendency toward a negative association was observed between 1,25(OH)₂D and S-Klotho plasma levels (β = -0.222, R² = 0.049, p = 0.059). The association was attenuated after controlling for age and sex and become significant after controlling for fat mass index. In addition, the association between 1,25(OH)₂D and S-Klotho levels was indirectly influenced by bone mineral density (BMD), with a percentage of mediation of 31.40%. Our study shows that 1,25(OH)₂D is negatively associated with S-Klotho plasma levels in middle-aged sedentary adults, which is partially mediated by BMD. Clinicaltrial.gov: ID: NCT03334357.