A letter published in the Archives of Internal Medicine revealed that treatment with 50,000 IU of vitamin D per week was safe over an 8-week period, and could also be used every other week as maintenance.
The researchers reviewed the records of 86 patients treated for vitamin D insufficiency. Forty-one subjects received 50,000 IU vitamin D2 weekly for 8 weeks followed by a maintenance dose of 50,000 IU every other week for up to 6 years. The remainder of the patients received every-other-week maintenance therapy.
For patients who received the starting therapy, 25-hydroxyvitamin D levels rose to 37.2 ng/mL after 8 weeks. Maintenance therapy increased these levels to 46.9 ng/mL. For those who received only maintenance therapy, vitamin D levels increased to 47 ng/mL.
“While treating and preventing vitamin D deficiency, these large doses of vitamin D2 do not lead to vitamin D toxicity,” researcher Michael Holick concluded.
It is interesting to see that even when these high doses of vitamin D2 are used, the average study subject did not attain optimal vitamin D blood levels of greater than 50 ng/mL. This further validates the importance for most people to take the Vitamin D3 form and have their blood tested for 25-hydroxyvitamin D (25(OH)D). Dosage adjustment can then be made to achieve optimal 25-hydroxyvitamin D status, which based upon the current scientific literature appears to be 50-80 ng/mL.
Arch Int Med. 2009 Oct 26;169(19).