Single 300,000 IU Vitamin D dose lasts about 2 months
Pharmacokinetics and effects of demographic factors on blood 25(OH)D3 levels after a single orally administered high dose of vitamin D3.

Acta Pharmacol Sin. 2016 Nov;37(11):1509-1515. doi: 10.1038/aps.2016.82. Epub 2016 Aug 29.
Chen PZ1, Li M1, Duan XH1,2, Jia JY3, Li JQ1, Chu RA1, Yu C3, Han JH4, Wang H1,2,4.
* Loading dose of 300,000 IU of vitamin D does not last long – March 2014
Note the large variation in the individual responses
* some got much higher than mean response
* some got virtually no resonse
* see Reasons for low response to vitamin D - includes
* poor health, very deficient, obese, poor liver, poor gut, gallbladder removed, old age,
AIM:
To examine the biological consequences and demographic factors that might affect the pharmacokinetics of vitamin D3 after a single high dose intervention in a young Chinese population with vitamin D insufficiency status.
METHODS:
A total of 28 young subjects (25 to 35 years old) with vitamin D insufficiency status [serum 25(OH)D <30 ng/mL] was recruited in Shanghai, China. The subjects were orally administered a single high dose of vitamin D3 (300 000 IU). Baseline characteristics and blood samples were collected at d 0, 1, 2, 3, 7, 28, 56, 84 and 112 after the intervention. The blood biomarker levels were determined with standardized methods.
RESULTS:
The intervention markedly increased the blood 25(OH)D3 levels within the first five days (mean Tmax=5.1±2.1 d) and sustained an optimal circulating level of 25(OH)D3 (=30 ng/mL) for 56 d. After the intervention, body weight and baseline 25(OH)D3 levels were significantly correlated with circulating 25(OH)D3 levels. No adverse events and no consistently significant changes in serum calcium, creatinine, glucose, parathyroid hormone, vitamin D binding protein, or the urinary calcium/reatinine ratio were observed. However, there was a significant increase in phosphorus after the vitamin D3 intervention. Total cholesterol and triglyceride levels were decreased at the end of the trial.
CONCLUSION:
The pharmacokinetics of vitamin D after intervention were influenced by baseline 25(OH)D3 levels and the body weight of the subjects. The results suggest that a single high oral vitamin D3 intervention is safe and efficient for improving the vitamin D status of young Chinese people with vitamin D insufficiency.
PMID: 27569392 DOI: 10.1038/aps.2016.82 Publisher rents PDF for $4