Association of weekly or biweekly use of 50 000 IU vitamin D3 with hypervitaminosis D.

Since the beginning of the COVID-19 pandemic, many Iranian people have been taking 50 000 IU of vitamin D3 on weekly or biweekly bases in order to enhance their immune system function. This cross-sectional study was conducted on the patients of endocrinology clinic to compare 25(OH)D levels of weekly or biweekly consumption with the monthly users of vitamin D3 50 000 IU. The level >100 ng/mL of 25(OH)D was defined as hypervitaminosis D. In total, 211 patients (108 and 103 patients in monthly and weekly/biweekly groups, respectively) were studied. In the subgroups of weekly and biweekly users, the rates of hypervitaminosis were 18.9% and 4.5%, respectively. In contrast, only 0.9% of monthly users had hypervitaminosis D. The highest vitamin D value of 185 ng/mL was detected in a patient who had consumed 50 000 IU vitamin D3 weekly for 6 years. No hypercalcaemia was detected in patients with hypervitaminosis D.