Object: There have been many studies reporting the benefit of high dose vitamin D supplementations worldwide. We tried to provide unbiased information regarding the safety and efficacy of high dose supplementation of vitamin D. Method: PubMed database search was done with key words “vitamin D” and “high dose” to select the original research articles. Final selection comprised two research papers, one reporting the effect of vitamin D on cardiovascular disease, the other on the lowered risk of infection. Results: While there could still be some benefits from vitamin D supplementation, both reports failed to demonstrate the statistical significance of the beneficial roles of vitamin D. While the toxicity of high dose vitamin D supplementation is rare and unlikely, there is no strong evidence of the benefit from high dose vitamin D supplementation either. Conclusion: Clinical guidelines for vitamin D supplementation are presented here based on guidelines of Institute of Medicine (USA), Endocrine Society, and others explaining the recommended dietary allowances and upper limits, risk groups, pros and cons of supplementation.

Keywords: Vitamin D, Dietary supplements, Megavitamin therapy, Calcium