Vitamin D Status and Biochemical Markers Related to Bone Health among Premenopausal Women with Obesity

Abstract

Vitamin D is important for calcium homeostasis and skeletal health, while obesity may influence circulating vitamin D concentrations through altered metabolism and adipose tissue sequestration. This study assessed vitamin D status and selected biochemical markers related to bone health among premenopausal women with obesity. A case-control study was conducted among 120 women aged 18–40 years recruited from General Hospital Ijede, Ikorodu, Lagos State. Participants comprised 30 normal-weight controls and 90 women with obesity, categorised as mildly obese, moderately obese, and severely obese, with 30 participants in each group. Serum 25-hydroxyvitamin D, calcium, phosphorus, bone-specific alkaline phosphatase, and thyroid-stimulating hormone were analysed using standard laboratory methods. Data were analysed using analysis of variance, Pearson correlation, and chi-square tests at p ≤ 0.05. Vitamin D concentrations differed significantly across groups, with lower levels in mildly obese, moderately obese, and severely obese women than in controls. Calcium concentrations were also significantly lower among women with obesity, while phosphorus showed a modest but significant difference. Bone-specific alkaline phosphatase and thyroid-stimulating hormone did not differ significantly across groups. A significant negative correlation was observed between vitamin D and body mass index in severely obese women. Calcium deficiency was more frequent among women with obesity than among controls. These findings indicate that obesity is associated with lower vitamin D and calcium concentrations among premenopausal women, and calcium status may be important in assessing bone health in this population.