Too much vitamin D? a drug safety review

Vitamin D is an essential pro-hormone that helps to regulate mineral metabolism and skeletal health. Epidemiological data suggest that many individuals have insufficient serum levels of 25-hydroxy vitamin D, the marker of vitamin D status, for most of the year. Recognition of this observation has led to replacement regimens for vitamin D that have often led to its overuse even in disorders not related to bone homeostasis. Since vitamin D toxicity is rare, safety issues related to vitamin D supplementation have not been carefully addressed recently. Overall safety issues related to administration of vitamin D pro-hormones from nutritional sources and from supplements are reviewed, along with recommendations for correct intakes. Traditional and new areas in which an improper use of vitamin D may occur are specifically addressed. Supplementation with vitamin D pro-hormones is effective and safe at usual daily, weekly or monthly doses that are recommended to maintain optimal mineral homeostasis. Monitoring is generally not mandatory once the desired level of serum 25(OH)D is obtained. However, clinical circumstances often change from year to year, in which cases confirmation of the adequacy of 25(OH)D is reasonable. When calcidiol is used, long term, monitoring is expected. Ingestion of excessive amounts of vitamin D, either through overprescribing or overdosing, is potentially harmful.