Scripted D Fail.

On March 22, 2010, in Fat Solubles, Vitamins, by Andrea

Going back to my roots a bit and explain a common problem in the WLS community — scripted vitamin D supplements.


Drisdol is the trade name for the prescription strength vitamin D treatment.  It is 50,000 IU of D2, suspended in an oil-base.  The typical regimen is 1 per week for 8 or 12 weeks, then retest.  This is in additional to the vitamin D that is packaged in calcium supplements and possibly additional vitamin D taken through the week depending on the prescriber.

Consider the following:

The case against ergocalciferol (vitamin D2) as a vitamin supplement1,2

Lisa A Houghton and Reinhold Vieth

1 From the School of Nutrition and Dietetics, Acadia University, Wolfville, Canada (LAH); the Department of Nutritional Sciences, University of Toronto, Toronto, Canada (RV); and the Mount Sinai Hospital, Toronto, Canada (RV)

Supplemental vitamin D is available in 2 distinct forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Pharmacopoeias have officially regarded these 2 forms as equivalent and interchangeable, yet this presumption of equivalence is based on studies of rickets prevention in infants conducted 70 y ago. The emergence of 25-hydroxyvitamin D as a measure of vitamin D status provides an objective, quantitative measure of the biological response to vitamin D administration. As a result, vitamin D3 has proven to be the more potent form of vitamin D in all primate species, including humans. Despite an emerging body of evidence suggesting several plausible explanations for the greater bioefficacy of vitamin D3, the form of vitamin D used in major preparations of prescriptions in North America is vitamin D2. The case that vitamin D2 should no longer be considered equivalent to vitamin D3 is based on differences in their efficacy at raising serum 25-hydroxyvitamin D, diminished binding of vitamin D2 metabolites to vitamin D binding protein in plasma, and a nonphysiologic metabolism and shorter shelf life of vitamin D2. Vitamin D2, or ergocalciferol, should not be regarded as a nutrient suitable for supplementation or fortification.

Vitamin D2 Is Much Less Effective than Vitamin D3 in Humans

VitaminsD2 andD3 are generally considered to be equivalent in humans.  Nevertheless, physicians commonly report equivocal responses to seemingly large doses of the only high-dose calciferol (vitaminD2) available in the U.S. market.  The relative potencies of vitamins D2 and D3 were evaluated by administering single doses of 50,000 IU of the respective calciferols to 20 healthy male volunteers, following the time course of serum vitamin D and 25-hydroxy  vitamin D (25OHD) over  a period of 28 d and measuring the area under the curve of the rise in 25OHD above baseline.  The two calciferols produced similar rises in serum concentration of the administered vitamin, indicating equivalent absorption.  Both produced similar initial rises in serum 25OHD over the first 3d, but 25OHD continued to rise in the D3-treated subjects, peaking at 14d, where as serum 25OHD fell rapidly in the D2-treated subjects and was not different from baseline at 14d.  Area under the curve (AUC) to d28 was 60.2ngd/ml (150.5nmold/liter) for vitamin D2 and 204.7 (511.8) for vitamin D3 (P < 0.002).  Calculated AUC  indicated an even greater differential, with the relative potencies for D3:D2 being 9.5:1.  Vitamin D2 potency is less than one third that of vitaminD3.  Physicians resorting to use of vitamin D2 should be aware of its markedly lower potency and shorter duration of action relative to vitamin D3.  (J Clin Endocrinol Metab 89:5387–5391,

So for all intents and purposes, we see that D2 is not as good as D3.  I had heard that it takes 10 units of D2 to make a single unit of D3, but since I couldn’t readily find that reference, I’m going to use the 3 units for now.  50,000 IU of D2 would be equivalent to approximately 16,666 IU of D3 after conversion.  If it’s the 10 units of D2 for every unit of D3 like I have heard previously, then the number is more like 5,ooo IU of D3 — which is exactly what you can get off the shelf at your local CVS.

However, after a malabsorbptive procedure like the Roux-en-Y gastric bypass or the Duodenal Switch, we heavily malabsorb fats and oils — including the oil this D2 is immersed in.  This means we get even less of that 50,000 IU to begin with.  I can’t even guess exactly how much, but let’s guess 50% of that.  Let’s say 25,000 IU of D2.  Using the 1/3rd figure, we get 8333 IU of D3 and using the 1/10th figure, we get 2,500 IU of D3.  Both are significantly less than the 50,000 IU scripted originally.

What we really need to realize is this — normal-gutted folks need 2,000 IU of supplemental vitamin D to simply maintain their levels.  After our re-routing, we are nowhere near normal, and we need to accept this fact.  Rather than use the prescription, there is a water-miscible, or “dry” version of D3 that will work much better with our designer anatomy.

Vitamin D3-5

Please take the time to read the above links, print them out and be prepared in case you are faced with a low vitamin D level.

Remember that we care about the 0,25(OH)D level.  The 1,25(OH)D level is only a level to check for compliance — it does not tell us anything about our actual vitamin D status.  The 0,25(OH)D, or simply 25(OH)D level paired with a parathyroid hormone level (PTH) tells us the state of our bones.

Vitamin D is critical in maintaining our bone health.  Without adequate D levels, we could get osteomalacia (adult-form rickets) — which, let me tell you from personal experience?  Hurts.  Osteopenia.  Osteoporosis.  Higher chances for cancer, heart disease, diabetes, stroke.

It’s important — take the right stuff when the time comes.

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