Thursday, 14 August 2014

Will there ever be a consensus on what dose of vD to take?

Vitamin D supplementation: 5,000 is the magic number #MSBlog #MSResearch

"The following paper provides an equation on how to calculate what dose of vD level is needed to raise vD levels. Interesting the average dose required was 4707IU/day, not far from 5,000IU/day recommended by the Vitamin D Council. Is this a conincidence? What is clear that the current RDA that was derived from studies on cod liver oil supplementation for the prevention of rickets is far too low."

Singh G, Bonham AJ. A predictive equation to guide vitamin d replacement dose in patients. J Am Board Fam Med. 2014 Jul-Aug;27(4):495-509.

BACKGROUND:  Vitamin D is essential for bone health and probably the health of most non-skeletal tissues. Vitamin D deficiency is widespread, and recommended doses are usually inadequate to maintain healthy levels. We conducted a retrospective observational study to determine whether the recommended doses of vitamin D are adequate to correct deficiency and maintain normal levels in a population seeking health care. We also sought to develop a predictive equation for replacement doses of vitamin D.

METHODS: We reviewed the response to vitamin D supplementation in 1327 patients and 3885 episodes of vitamin D replacement and attempted to discern factors affecting the response to vitamin D replacement by conducting multiple regression analyses.

RESULTS: For the whole population, average daily dose resulting in any increase in serum 25-hydroxyvitamin D level was 4707 IU/day; corresponding values for ambulatory and nursing home patients were 4229 and 6103 IU/day, respectively. Significant factors affecting the change in serum concentrations of 25-hydroxyvitamin D, in addition to the dose administered, are (1) starting serum concentration of 25-hydroxyvitamin D, (2) body mass index (BMI), (3) age, and (f) serum albumin concentration. The following equation predicts the dose of vitamin D needed (in international units per day) to affect a given change in serum concentrations of 25-hydroxyvitamin D: Dose = [(8.52 - Desired change in serum 25-hydroxyvitamin D level) + (0.074 × Age) - (0.20 × BMI) + (1.74 × Albumin concentration) - (0.62 × Starting serum 25-hydroxyvitamin D concentration)]/(-0.002). Analysis of thedose responses among 3 racial groups-white, black, and others-did not reveal clinically meaningful differences between the races. The main limitation of the study is its retrospective observational nature; however, that is also its strength in that we assessed the circumstances seen in usual health care setting.

CONCLUSIONS: The recommended daily allowance for vitamin D is grossly inadequate for correcting low serum concentrations of 25-hydroxyvitamin Din many adult patients. About 5000 IU vitamin D3/day is usually needed to correct deficiency, and the maintenance dose should be ≥2000 IU/day. The required dose may be calculated from the predictive equations specific for ambulatory and nursing home patients.


  1. As 25(OH)D has a half life in the body, the maintenance dose cannot be lower than the dose that got you to that steady level in the first place. If 5000IU a day is needed to correct the deficiency it is also needed to maintain that level.

  2. This work was done in Kansas City which is 39 degrees North, so same as Ibiza Spain.


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