D2d Publication: Safety and tolerability of high-dose daily vitamin D3 supplementation in the vitamin D and type 2 diabetes (D2d) study—a randomized trial in persons with prediabetes
Routine use of vitamin D supplements has increased substantially in the United States. However, the safety and tolerability of long-term use of high-dose vitamin D are not known.
This pre-specified analysis in D2d assessed the safety and tolerability of vitamin D3 at a dose of 4000 IU per day in a population that is overweight/obese and at high risk for diabetes. Safety events, including laboratory values (e.g., calcium) and outcomes (e.g., kidney stones), were carefully recorded during the course of the study. During 3 years of follow-up, adverse events were less frequent in the vitamin D group compared to placebo. The overall frequency of protocol-specified adverse events of interest, which included nephrolithiasis, hypercalcemia, hypercalciuria, or low estimated glomerular filtration rate, was low and did not differ by group. There were no significant between-group differences in total serious adverse events.
Routine use of vitamin D supplements has increased substantially in the United States. These results provide reassuring data of the safety and tolerability of long-term use of high-dose vitamin D.
The manuscript is published in European Journal of Clinical Nutrition.