ORLANDO – after 2 years of daily use, according to data presented at the annual meeting of the American Society for Bone and Mineral Research.
“Participants may have already reached the vitamin D level needed for bone health,” Meryl S. LeBoff, MD, of Brigham and Women’s Hospital in Boston, said in her presentation.
Dr. LeBoff presented results from 771 patients (mean age, 63.8 years) in the Bone Health Subcohort of VITAL (Vitamin D and OmegA-3 TriaL) who were not on any bone active medications and were randomized to receive daily vitamin D3 at a dose of 2,000 IU or placebo. Patients received bone imaging at baseline and at 2 years; areal bone mineral density (aBMD) of the whole body, femoral neck, total hip, and spine was assessed via dual x-ray absorptiometry scan. Total 25-hydroxyvitamin D (25[OH]D) levels were measured via liquid chromatography tandem mass spectrometry, and free 25(OH)D levels were measured via the ELISA assay. The baseline characteristics of the vitamin D3 supplementation and placebo groups were similar. Overall, 52% of patients had osteopenia and 10.4% had osteoporosis.
Between baseline and 2 years, the vitamin D group’s total 25(OH)D levels increased from a mean 27.0 ng/mL to 39.5 ng/mL (46%) and the free 25(OH)D levels increased from 5.8 pg/mL to 9.0 pg/mL (55%), whereas levels in the placebo stayed the same. The researchers found no significant absolute percentage changes over 2 years in aBMD of the whole body (P = .60), femoral neck (P = .16), total hip (P = .23) and spine (P = .55), compared with patients in the placebo group.
In a secondary analysis, Dr. LeBoff and colleagues found no benefit to volumetric BMD (vBMD) of the radius and the tibia at 2 years, and the results persisted after they performed a sensitivity analysis. Adverse events, such as hypercalciuria, kidney stones, and gastrointestinal symptoms, were not significantly different in the vitamin D group, compared with the placebo group.
Dr. LeBoff noted among the limitations of the study that it evaluated one dose level of vitamin D and was not designed to determine whether vitamin D supplementation was effective in people with vitamin D insufficiency, and the results are not generalizable to patients with osteoporosis or osteomalacia. Future studies should also examine whether free 25(OH)D levels can be used to detect which patients can benefit from vitamin D supplementation, she added.
Risk of falls
In a separate abstract, which Dr. LeBoff presented in a different session, 12,927 patients who received vitamin D supplementation for 5 years, were studied for risk of falls, compared with 12,994 individuals in a placebo group. At baseline, 33.3% of patients had fallen at least once in the previous year, and overall 6,605 patients reported 13,235 falls. At 5.3 years of follow-up, there were no significant differences in number of falls between groups, falls leading to injury, and falls leading to a doctor or a hospital visit.
There are ongoing parallel studies examining the incidence of fractures between groups in the total population of the VITAL study (25,871 participants); bone turnover markers; bone microarchitecture measurements through high-resolution peripheral quantitative computed tomography; and examining the connection between free 25(OH)D, parathyroid hormone, and vitamin D binding protein, said Dr. LeBoff.
The study was funded in part by grants from the National Cancer Institute, the National Heart, Lung and Blood Institute, the Office of Dietary Supplements, the National Institute of Neurological Disorders and Stroke, and the National Center for Complementary and Integrative Health. Dr. LeBoff reported receiving grants from the National Institute of Arthritis Musculoskeletal and Skin Diseases. Two authors reported nonfinancial support Pharmavite LLC of Northridge, Calif., Pronova BioPharma of Norway and BASF, and Quest Diagnostics. The remaining authors reported no conflicts of interest.
SOURCE: LeBoff M et al. ASBMR 2019, Abstracts 1046 and 1057.