January 24, 2011

RDA for Vitamin D Needs Change

At least I feel vindicated by what I said in my blog of December 20, 2010. Others including Dr. Miller are also pointing out more accurately the problems of the report issued by Institute of Medicine of the National Academies of Science (IOM). There are some glaring errors that punch holes in the report by IOM. These errors make me wonder how these men of science could miss this or do they simply lack the education necessary for their duties.

Harsh, yes. But these errors are serious. Even David Mendosa has told me to be careful not to take vitamin-D2, but to take vitamin-D3. What bothers me is that people will go to the doctor for a vitamin D prescription and pay the doctor fee and a higher cost for vitamin-D2, when vitamin-D3 is on the shelves and a lot cheaper.

Vitamin-D2 is much less effective in humans than vitamin-D3. D2 is largely human made and added to foods as a fortifier. Vitamin-D3 is also consumed by consuming animal based foods. So those on non-meat lifestyles, should have their doctor check their vitamin D levels and consider taking vitamin-D3 supplements.

Vitamin D, also known as calciferol, comprises a group of fat-soluble seco-sterols. The two major forms are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). In addition to having markedly lower potency, D2 also has a significantly shorter duration of action relative to vitamin D3. Both forms of vitamin D produce similar initial rises in serum 25OHD over the first 3 days, but 25OHD continues to rise with D3 supplementation, peaking at 14 days, and serum 25OHD falls rapidly in D2 treated subjects.

I think that this statement in the American Journal of Clinical Nutrition is most effective and needs to be heeded. They say that vitamin-D2 should not be used as a nutrient suitable for supplementation or fortification.

Dr Miller's blog is well stated and has some excellent comments to read here and read his latest blog here. Jon Barron writes his understanding of the IOM study and publishing of standards here. He is very factual and reports on the errors.  NOTE:  The two links for Dr. Miller's information are no longer functional.

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