Effect of Monthly and Bi-Monthly 50,000 International Units (IU) Maintenance Therapy With Vitamin D3 on Serum Level of 25-Hydroxyvitamin D in Adults: A Randomized Controlled Trial

Background Vitamin D deficiency is a prevalent condition worldwide. Identification of optimal supplementation approaches for maintaining normal vitamin D level in healthy adults is still required. It has been clearly established that sun exposure and diet do not provide the recommended daily amount of vitamin D, and that vitamin D supplementation is needed to maintain normal levels in the Saudi population. The aim of this study was to compare the efficacy of two regimens, monthly and bimonthly doses of 50,000 International Units (IU) cholecalciferol (vitamin D3), in maintaining normal serum levels of 25-hydroxyvitamin D in Saudi adults. Methods This study was a randomized controlled trial conducted to compare the efficacy of three regimens in maintaining a normal level of vitamin D in adult individuals. The study took place at three primary healthcare centers in King Abdul-Aziz Medical City, Riyadh, Saudi Arabia. A total of 65 participants were enrolled and randomly divided into two intervention groups and one control group. All participants were contacted by researchers and followed up at their corresponding primary health care center for two successive visits. Results All 65 participants completed the study. The participants were mostly females (49; 75.4%); the mean age was 42.1 years (±13.5). The difference in vitamin D levels after three months of the trial was statistically significant among the three groups. A decrease in vitamin D level was recorded in the control group and in the once monthly intake of 50,000 IU group. The bimonthly intake of 50,000 IU group maintained statistically significant vitamin D levels > 75. Conclusion Bimonthly vitamin D3 supplementation appears to be an efficient regimen for maintaining a normal level of 25(OH)D, regardless of the amount of vitamin D obtained from diet and sun exposure.