Effect of Non-Pharmacologic Vitamin D Status Correction on Circulating Bone Markers in Healthy Overweight and Obese Saudis

While moderate to severe vitamin D deficiency is prevalent in Saudi Arabia, skeletal effects associated with this deficiency are not common in this population. In this interventional study we measured the effects of improving vitamin D status on bone biochemical markers in overweight and obese adult Saudis. A total of 47 volunteers (21 males, 26 females) out of the initial 95 subjects were given verbal advice to expose themselves to sunlight for 5-30 min twice weekly and were encouraged to increase their intake of vitamin D-rich foods. Serum 25(OH) D, osteocalcin, and type 1 collagen cross-linked C-telopeptide (CTx), were measured at baseline and after one year. A significant decrease in the prevalence of vitamin D deficiency was observed (44% to 27%) after one year follow-up (p = 0.025). Also, a parallel significant increase in osteocalcin and a decrease in CTX and osteoprotegerin were observed. The results suggest that a modest increase in vitamin D levels among overweight and obese subjects through the promotion of lifestyle changes for one year have marginal effects in bone turnover markers as well as obesity itself.