LARGE, SINGLE-DOSE, ORAL VITAMIN D SUPPLEMENTATION IN ADULT POPULATIONS: A SYSTEMATIC REVIEW
Correction of vitamin D insufficiency is commonly achieved using oral vitamin D supplements. The Endocrine Society guidelines suggest that daily intake of 1,500 to 2,000 international units (IU) of vitamin D is necessary to achieve serum 25(OH)D concentrations consistently >30 ng/mL in adults (18). However, adherence to daily doses has been reported to be low in several large clinical trials (1). Poor adherence has been associated with difficulty swallowing combined vitamin D/calcium tablets, gastrointestinal (GI) side-effects (21), the number of concurrent treatments a patient is receiving, and the patient’s attitude towards vitamin D supplementation (22). Vitamin D given as a large bolus dose has demonstrated higher adherence rates compared with daily and monthly dosing regimens, and has the potential to yield sustained improvements in serum 25(OH)D and parathyroid hormone (PTH) concentrations (23). The sustained effect of high-dose vitamin D may be attributed to its long half-life.