Effect of Vitamin D Supplementation According to Daily Dietary Levels on Biochemical Parameters in 25-Hydroxyvitamin D Deficiency of Women with Obesity.

Objectives: This study examined how vitamin D supplementation based on daily dietary intake affects biomarkers in obese women with 25-hydroxyvitamin D deficiency.

Materials and methods: Group D (n= 14) used vitamin D supplements daily for 2 months, and Group C (n= 16) did not receive supplements. Three blood samples were collected from the volunteers during the initial phase of the study. In this study, blood was collected from the volunteers: first measurement (M1), second measurement (M2), and third measurement (M3).

Results: Compared with Group C, Group D had lower high-density lipoprotein (HDL) levels at M2 and fasting serum glucose (FSG) levels at M3 (p < 0.05), and lower HDL levels at M2 and FSG levels in normal-weight individuals at M3 (p < 0.05). In addition, 25-hydroxyvitamin D levels were higher in normal-weight women than in obese women according to M3 (p= 0.043). There was a higher negative correlation between HDL-C in M1 and FSG in Group D (r= -0.710, p= 0.004). 25-hydroxyvitamin D was moderately positively correlated with dietary vitamin D in M2 in Group D (r= 0.559, p= 0.038). Significant positive correlations were observed between iodine intake and triiodothyronine (T3) levels, whereas no significant difference was observed between thyroid-stimulating hormone and T3 levels.

Conclusion: Vitamin D intake improves HDL levels in normal-weight individuals and causes an effect on FSG to be at the desired low level, whereas in individuals with obesity, although serum 25-hydroxyvitamin D levels increased in the last measurement, no effect was observed. Women with normal vitamin D levels have higher serum 25-hydroxyvitamin D levels than those who are obese.