what form of vitamin D is best?

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Meta-analysis of RCTs compares efficacy of D2 vs D3 supplementation

by Kate Saley<http://blog.vitamindcouncil.org/author/kate-saley/>

One of the most common questions we receive about vitamin D supplementation is

whether to use D2 or D3. Generally, studies show that D3 is more potent and more

efficacious, and it is also the " natural " form because it's what your own body

produces.

But let's look at a recent meta-analysis to settle the potency debate.

Tripkovic L, Lambert H, Hart K, CP, Bucca G, Penson S, Chope G, Hypponen

E, Berry J, Vieth R, Lanham-New S. Comparison of vitamin D2 and vitamin D3

supplementation in raising serum 25-hydroxyvitamin D status: a systematic review

and meta-analysis. Am J Clin Nutr. May

2012.<http://www.ncbi.nlm.nih.gov/pubmed/22552031>

http://www.ncbi.nlm.nih.gov/pubmed/22552031

Professor Tripkovic and colleagues at the University of Surrey reviewed 10

randomized controlled trials (RCTs) with a collective total of 1,016

participants ages 18-97. The studies included in the review encompassed a range

of different dosages and administration methods:

§ Two of the studies administered a single bolus dose of varying quantities,

one using alternate routes of administration (oral or intramuscular).

§ Six studies preferred daily supplementation with dosages ranging from 1,000

to 4,000 IU.

§ One study compared daily to monthly supplementation, 1,600 to 50,000

respectively, while another study supplemented 50,000 IU weekly.

§ The final study compared a single intramuscular injection of 300,000 IU of D2

to a single oral dose of 300,000 IU D3.

The researchers found:

§ In eight of the studies, regardless of the dose, frequency, or

administration, concluded that cholecalciferol (D3) produced a significantly

greater increase from baseline serum 25(OH)D levels compared with ergocalciferol

(D2).

§ Two studies showed D2 and D3 were equally effective.

The authors also determined whether frequency of dosage had an effect on

favoring of D2 or D3. Three out of the 4 studies which used bolus doses reported

results which favored using vitamin D3 to raise serum levels most effectively.

When focusing on the studies which used daily supplementation the results

weren't as strong, but a clear preference for cholecalciferol was present.

So the recommendation remains that D3 is preferable to D2 for better potency. If

your doctor prescribes vitamin D from a pharmacy (usually Drisdol), ask them if

you might be able to take alternative steps to ensure you receive vitamin D3

instead.

Abstract

BACKGROUND:

Currently, there is a lack of clarity in the literature as to whether there is a

definitive difference between the effects of vitamins D(2) and D(3) in the

raising of serum 25-hydroxyvitamin D [25(OH)D].

OBJECTIVE:

The objective of this article was to report a systematic review and

meta-analysis of randomized controlled trials (RCTs) that have directly compared

the effects of vitamin D(2) and vitamin D(3) on serum 25(OH)D concentrations in

humans.

DESIGN:

The ISI Web of Knowledge (January 1966 to July 2011) database was searched

electronically for all relevant studies in adults that directly compared vitamin

D(3) with vitamin D(2). The Cochrane Clinical Trials Registry, International

Standard Randomized Controlled Trials Number register, and clinicaltrials.gov

were also searched for any unpublished trials.

RESULTS:

A meta-analysis of RCTs indicated that supplementation with vitamin D(3) had a

significant and positive effect in the raising of serum 25(OH)D concentrations

compared with the effect of vitamin D(2) (P = 0.001). When the frequency of

dosage administration was compared, there was a significant response for vitamin

D(3) when given as a bolus dose (P = 0.0002) compared with administration of

vitamin D(2), but the effect was lost with daily supplementation.

CONCLUSIONS:

This meta-analysis indicates that vitamin D(3) is more efficacious at raising

serum 25(OH)D concentrations than is vitamin D(2), and thus vitamin D(3) could

potentially become the preferred choice for supplementation. However, additional

research is required to examine the metabolic pathways involved in oral and

intramuscular administration of vitamin D and the effects across age, sex, and

ethnicity, which this review was unable to verify.

S. Kalman PhD, RD, FACN

Director, BD - Nutrition & Applied Clinical Trials

Miami Research Associates

6141 Sunset Drive - Suite 301

Miami, FL. 33143

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