Endocrine Abstracts

Numerous studies have identified several extra-skeletal health outcomes to be associated with vitamin D deficiency, yet a definitive causal link is yet to be discovered. Our recent 3D LC-nESI-FTMS proteomic analysis among normal and overweight but apparently healthy adult Saudis identified apolipoproteins, a known independent cardiovascular risk factor, as one of the serological molecular signatures that modulate vitamin D levels. The present interventional study aims to compare and validate the identified apolipoproteins among vitamin D deficient subjects that have achieved full vitamin D status correction. 199 Saudi adults [89 males, mean age 42.0±10.4; BMI 28.6±4.4 kg/m²; 110 females, mean age 39.1±12.0; BMI 30.7±5.3] (with vitamin D deficiency [25(OH)D <50 nmol/l] were recruited and given 50 000 IU cholecalciferol (VitaD50000®) weekly for 2 months, then twice a month for 2 months, followed by daily 1000 IU (VitaD1000®) until month 6. Blood samples were taken at baseline and after 6 months. Serum 25(OH)D was measured using electrochemiluminescence and apolipoproteins (AI, AII, B, CI, CII, CIII and E) using commercially available kits. In all subjects, serum 25(OH)D increased significantly from baseline and after 6 months (32.6±11.1 vs 63.4±16.4 nmol/l; P<0.001). In parallel, a significant increase in apolipoproteins B, CI, CII, CIII and E (P-values<0.05) after 6 months compared to baseline was observed. After stratification according to sex, only apolipoproteins CII and CIII were significantly increased in males (P-values<0.001), and only apolipoprotein CI was significantly increased in females (P<0.001), showing sexual dimorphism in the effects of vitamin D with regards to apolipoprotein levels. The rest of the apolipoproteins were not significantly different pre- and post-vitamin D correction. The present study partially explains the effects of vitamin D correction in the reduction of cardiovascular risk through significant modification of apolipoproteins, particularly the apolipoprotein C class. These effects differ according to sex.