Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Am J Clin Nutr. 1999 May;69(5):842-56.
For adults, the 5-microg (200 IU) vitamin D recommended dietary allowance may prevent osteomalacia in the absence of sunlight, but more is needed to help prevent osteoporosis and secondary hyperparathyroidism. Other benefits of vitamin D supplementation are implicated epidemiologically: prevention of some cancers, osteoarthritis progression, multiple sclerosis, and hypertension. Total-body sun exposure easily provides the equivalent of 250 microg (10000 IU) vitamin D/d, suggesting that this is a physiologic limit. Sailors in US submarines are deprived of environmentally acquired vitamin D equivalent to 20-50 microg (800-2000 IU)/d. The assembled data from many vitamin D supplementation studies reveal a curve for vitamin D dose versus serum 25-hydroxyvitamin D [25(OH)D] response that is surprisingly flat up to 250 microg (10000 IU) vitamin D/d. To ensure that serum 25(OH)D concentrations exceed 100 nmol/L, a total vitamin D supply of 100 microg (4000 IU)/d is required. Except in those with conditions causing hypersensitivity, there is no evidence of adverse effects with serum 25(OH)D concentrations <140 nmol/L, which require a total vitamin D supply of 250 microg (10000 IU)/d to attain. Published cases of vitamin D toxicity with hypercalcemia, for which the 25(OH)D concentration and vitamin D dose are known, all involve intake of > or = 1000 microg (40000 IU)/d. Because vitamin D is potentially toxic, intake of >25 microg (1000 IU)/d has been avoided even though the weight of evidence shows that the currently accepted, no observed adverse effect limit of 50 microg (2000 IU)/d is too low by at least 5-fold.
3 thoughts on “Blood vitamin D levels”
So you are saying that its impossible to rise above 140 nmol/L if you take less that 10000uI/day? Currently my levels are 121 with only 4560uI/day. – with that amount what should my max level then be? (even better – how do you calculate such a thing?(approximated))But yes, if what you are saying is that its ok to be under 140nmol/L and being above _may_ cause some issues, then it answers my question.
Wow … I take 10,000 IU daily on days when I don't get out in the sun. On days when I go for a walk or am outside for a bit, I take 5,000 IU. My most recent level was 97.9 ng/mL. If I have the correct conversion, then that would be 244 nmol/L!!I seemed to have overshot my goal. However, as per the lab reference ranges (for the hospital reporting my results), I am at the upper limit of normal. The ranges are as follows:Deficiency = <10 ng/mL (25 nmol/L)Insufficiency = 10 – 25 ng/mL (25 – 75 nmol/L)Sufficiency = 30 – 100 ng/mL (75 – 250 nmol/L)Toxicity = >100 ng/mL (> 250 nmol/L)
Re: "So you are saying that its impossible to rise above 140 nmol/L if you take less that 10,000uI/day?"Very unlikely. vD levels are controlled by many factors, including genetic factors. If in doubt have your levels checked. "Currently my levels are 121 with only 4560uI/day. – with that amount what should my max level then be? (even better – how do you calculate such a thing?(approximated))"You can't calculate a max level. In addition, your levels will vary depending on sun exposure; being higher in summer than winter. It looks as if you don't need more than 4,000 per day.