Supplementation of vitamin D isolated or calcium-associated with bone remodeling and fracture risk in postmenopausal women without osteoporosis: A systematic review of randomized clinical trials

Menopause and vitamin D deficiency increase bone reabsorption and bone fracture risk in women in postmenopause, and vitamin D supplementation may improve bone health and decrease bone fracture risk. This study aims to discuss the effect of vitamin D supplementation, isolated or calcium-associated, on remodeling and fracture risk bone in women in postmenopause without osteoporosis. This study was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PROSPERO database registration: CRD42022359796). A search was conducted in four databases and gray literature using MeSH and similar terms related to supplements, vitamin D, calcium, remodeling, and fracture bone, without the restriction of language and year of publication. A total of 3460 studies were identified, and nine were selected. Vitamin D supplementation increased 25-hydroxyvitamin D levels ≥10 ng/mL and decreased parathyroid hormone secretion dependent on baseline levels. The doses of 400 IU of vitamin D improved the percentage of carboxylated osteocalcin, whereas 800 to 1000 IU combined with calcium resulted in reduced, improved, or maintained bone mineral density and reduced alkaline phosphatase levels. However, 4000 IU alone or combined with calcium for 6 mo did not improve C-telopeptide and procollagen type 1 peptide levels. Additionally, 15 000 IU/wk increased the cortical area of metacarpal bone, whereas 500 000 IU of vitamin D annually for 5 y did not contribute to reducing the fracture risk and falls. Only one study found a reduction in fracture risk (dose of 800 IU of vitamin D plus 1200 mg of calcium). Thus, the vitamin D supplementation, alone or calcium-associated, improved the status of 25-hydroxyvitamin D and bone remodeling, but it was not possible to assert that it reduced fracture bone risk in postmenopausal women.