Who We Are
Articles - Health
Free MFZ Kits
MFZ in India
Woodstock Animal Rights Movement
A Store For Life
P. O. Box 746
Woodstock, NY 12498 USA
Vitamin D2 Is as Effective as Vitamin D3 in Maintaining Circulating Concentrations of 25-Hydroxyvitamin D
Michael F. Holick, Rachael M. Biancuzzo, Tai C. Chen, Ellen K. Klein,
Azzie Young, Douglass Bibuld, Richard Reitz, Wael Salameh, Allen Ameri,
and Andrew D. Tannenbaum
Endocrine Section (M.F.H., R.M.B., T.C.C., E.K.K., A.A., A.D.T.),
Department of Medicine, Boston University School of Medicine, Boston,
Massachusetts 02118; Mattapan Community Health Center (A.Y., D.B.),
Mattapan, Massachusetts 02126; and Quest Diagnostics Nichols Institute
(R.R., W.S.), San Juan Capistrano, California 92675
Address all correspondence and requests for reprints to: Michael F.
Holick, Boston University School of Medicine, 715 Albany Street, M-1013,
Boston, Massachusetts 02118. E-mail:
Context: Two reports suggested that vitamin D2 is less effective
than vitamin D3 in maintaining vitamin D status.
Objective: Our objective was to determine whether vitamin D2 was
less effective than vitamin D3 in maintaining serum 25-hydroxyvitamin D
levels or increased the catabolism of 25-hydroxyvitamin D3.
Subjects and Design: This was a randomized, placebo-controlled,
double-blinded study of healthy adults ages 18–84 yr who received
placebo, 1000 IU vitamin D3, 1000 IU vitamin D2, or 500 IU vitamin D2
plus 500 IU vitamin D3 daily for 11 wk at the end of the winter.
Results: Sixty percent of the healthy adults were vitamin D
deficient at the start of the study. The circulating levels of
25-hydroxyvitamin D (mean ± sd) increased to the same extent in the
groups that received 1000 IU daily as vitamin D2 (baseline 16.9 ± 10.5
ng/ml; 11 wk 26.8 ± 9.6 ng/ml), vitamin D3 (baseline 19.6 ± 11.1 ng/ml;
11 wk 28.9 ± 11.0 ng/ml), or a combination of 500 IU vitamin D2 and 500
IU vitamin D3 (baseline 20.2 ± 10.4 ng/ml; 11 wk 28.4 ± 7.7 ng/ml). The
25-hydroxyvitamin D3 levels did not change in the group that received
1000 IU vitamin D2 daily. The 1000 IU dose of vitamin D2 or vitamin D3
did not raise 25-hydroxyvitamin D levels in vitamin D-deficient subjects
above 30 ng/ml.
Conclusion: A 1000 IU dose of vitamin D2 daily was as effective
as 1000 IU vitamin D3 in maintaining serum 25-hydroxyvitamin D levels
and did not negatively influence serum 25-hydroxyvitamin D3 levels.
Therefore, vitamin D2 is equally as effective as vitamin D3 in
maintaining 25-hydroxyvitamin D status.
Vitamin D2, which comes from the UV irradiation of ergosterol
obtained from yeast, has been the mainstay for the prevention and
treatment of vitamin D deficiency in children and adults for more than
As little as 100 IU vitamin D2 was found to be effective in the
prevention of rickets.
When humans are exposed to sunlight, 7-dehydrocholesterol in the skin
absorbs UVB (290–315 nm) radiation resulting in the production of
Vitamin D3 is found naturally in cod liver oil and oily fish such as
Vitamin D3 is also made by irradiating 7-dehydrocholesterol obtained
from lanolin from sheep’s wool with UVB radiation.
Both vitamin D2 and vitamin D3 when ingested undergo metabolism in the
liver to form 25-hydroxyvitamin D [25(OH)D; D represents either D2 or
D3] and in the kidneys to 1,25-dihydroxyvitamin D.
Both vitamin D2 and vitamin D3 are available in supplements, but only
vitamin D2 is available as a pharmaceutical preparation because its use
predated the Food and Drug Administration and, thus, was grandfathered
as a pharmaceutical drug. Vitamin D3 was commercially developed in the
1950s and has not been approved as a pharmaceutical agent in the United
States but is used in food supplementation and vitamin supplements.
Since the 1930s, vitamin D2 has been considered to be equally as
effective as vitamin D3 for bone health.
Recently, it was suggested that vitamin D2 was less effective than
vitamin D3 in maintaining serum 25(OH)D levels when given either as 4000 IU/d for 2 wk
or as a single dose of 50,000 IU.
Furthermore, it was observed that when a single dose of 50,000 IU
vitamin D2 was given to healthy adults that the serum 25(OH)D levels
decreased more rapidly than the placebo group, suggesting that vitamin
D2 not only was less effective in maintaining serum 25(OH)D levels but
also enhanced the degradation of 25(OH)D3.
These two observations have led to the conclusion that vitamin D2 is
approximately 30–50% as effective as vitamin D3 in maintaining serum
25(OH)D in humans.
Our purpose was to evaluate in healthy adults what the effect of
ingesting 1000 IU vitamin D2, 1000 IU vitamin D3, or a combination of
500 IU vitamin D2 and 500 IU vitamin D3 daily for 11 wk at the end of
the winter had on circulating levels of total 25(OH)D as well as
25(OH)D2 and 25(OH)D3.
Subjects and Methods
Healthy, white, African-American, Hispanic, Asian, and Native
American adults between the ages of 18 and 84 yr were enrolled in
February 2007 after signing a consent form approved by our Institutional
Review Board at Boston University Medical Center. We excluded those with
chronic liver and kidney disease and those taking medications, including
anticonvulsants, glucocorticoids, and barbiturates, that might affect
vitamin D metabolism as well as subjects who were taking a vitamin D
supplement. Subjects were permitted to take their multivitamin, a
majority of which contained 400 IU vitamin D3 (Table 1).
Sixty-eight subjects were randomly assigned in a double-blinded
fashion to receive daily in a capsule for 11 wk 1) placebo, 2) 1000 IU
(25 μg) vitamin D2 (ergocalciferol), 3) 1000 IU (25 μg) vitamin D3
(cholecalciferol), or 4) 500 IU vitamin D2 plus 500 IU vitamin D3. All
of the capsules made by Tishcon Corp. (Salisbury, MD) contained lactose
(98.75%), magnesium stearate (1.0%), and silicon dioxide (1.25%). All of
the products were analyzed in our laboratory by HPLC and found to
contain either no vitamin D (placebo) or concentrations within 10% of
their specified content. All subjects had blood samples collected at
baseline and every week for a total of 11 wk. Each subject was given a
dietary questionnaire at baseline to assess multivitamin and milk
consumption. Pill compliance (Table 1)
was determined by a pill count at each visit.
Serum 25(OH)D2 and 25(OH)D3 were determined by liquid chromatography
tandem mass spectroscopy at Quest Diagnostics Nichols Institute, San
Juan Capistrano, CA.
The detection limit for the assay was 4 ng/ml, and the interassay
coefficient of variation was about 10%. Values for serum 25(OH)D2
reported as less than 4 ng/ml were obtained by subtracting 25(OH)D3 from
the total 25(OH)D.
The results are presented as means ± sd. Data were analyzed using
mixed-effects regression to perform a repeated-measures analysis of
25(OH)D levels across time and groups. Pairwise comparisons were
performed between all treatment groups as well as each treatment group
vs. placebo. Interactions between treatment group and time
compared the linear change in 25(OH)D over time between the groups. A
repeated-measures mixed-effect model also compared the 25(OH)D2 and
25(OH)D3 across visits for each of the treatment groups. Statistical
analysis was performed using SAS (SAS Institute, Inc., Cary, NC).
Sixty percent of our healthy adult subjects were vitamin D deficient
[25(OH)D < 20 ng/ml], and 87% were insufficient [25(OH)D < 30 ng/ml],
even though about 29% took a multivitamin daily that contained 400 IU
vitamin D and about 47% drank about 1.2 glasses of milk per day. Adults
who received the placebo capsule daily for 3 months demonstrated no
significant change in their total 25(OH)D levels during the winter and
early spring (Fig. 1).
Adults who ingested 1000 IU vitamin D2/d gradually increased their total
25(OH)D levels from 16.9 ± 10.5 ng/ml to 25.8 ± 6.6 ng/ml during the
first 6 wk and then remained stable (Fig. 1).
Adults who ingested 1000 IU vitamin D3 had a baseline 25(OH)D of 19.6 ±
11.1 ng/ml that was statistically no different from the baselines of
either the placebo group or the groups that took 1000 IU vitamin D2/d or
500 IU vitamin D2 plus 500 IU vitamin D3/d (P = 0.79). The
vitamin D3 group increased their serum 25(OH)D levels similar to that of
the group that ingested vitamin D2. The 25(OH)D levels in the vitamin D3
group began to plateau by wk 6 and was 28.9 ± 11.0 ng/ml at the end of
the study, which was not statistically different from the vitamin D2
group (26.8 ± 9.6 ng/ml) (Fig. 1).
Mean (± sem) serum 25(OH)D levels after oral administration of
vitamin D2 and/or vitamin D3. Healthy adults recruited at the
end of the winter received placebo (•; n = 14), 1000 IU vitamin
D3 (D3, ; n = 20), 1000 IU vitamin D2 (D2, ; n = 16), or 500 IU
vitamin D2 and 500 IU vitamin D3 [D2 and D3, ♦; n = 18) daily
for 11 wk. The total 25(OH)D levels are demonstrated over time.
*, P = 0.027 comparing 25(OH)D over time between vitamin D3 and
placebo; **, P = 0.041 comparing 25(OH)D over time between 500
IU vitamin D3 plus 500 IU vitamin D2 and placebo; ***, P = 0.023
comparing 25(OH)D over time between vitamin D2 and placebo
To determine whether vitamin D2 ingestion had any effect on
circulating levels of 25(OH)D3, we determined 25(OH)D2 and 25(OH)D3 in
the samples. The 25(OH)D2 levels increased from undetectable (<4 ng/ml)
to 14 ± 5.3 ng/ml by wk 6 and remained at approximately 14 ng/ml for the
ensuing 5 wk in the group that received 1000 IU vitamin D2 (Fig. 2A).
The baseline 25(OH)D3 level in the same subjects was 15.1 ± 9.8 ng/ml
and did not significantly change during the entire study and was 13.6 ±
10.2 ng/ml at the end of the study (P = 0.14) (Fig. 2A).
Similarly, the group that received vitamin D3 showed no significant
change in the serum 25(OH)D2 throughout the study (P = 0.33)
Effect of vitamin D2 or vitamin D3 on serum 25(OH)D2 and
25(OH)D3 levels. Serum levels of 25(OH)D2 () and serum 25(OH)D3
(♦) were measured in healthy subjects receiving 1000 IU vitamin
D2 (A), 1000 IU vitamin D3 (B), or 500 IU vitamin D2 plus 500 IU
vitamin D3 (C) daily for 11 wk. Results are presented as means ±
sem over time. *, P < 0.0001 comparing 25(OH)D2 between baseline
and 11 wk (A); *, P < 0.0001 comparing 25(OH)D3 between baseline
and 11 wk (B); *, P = 0.0014 comparing between 25(OH)D3 and
placebo group (C); **, P = 0.0031 comparing 25(OH)D2 and placebo
group (C). Note serum 25(OH)D2 levels less than 4 ng/ml were
obtained by subtracting the total 25(OH)D3 from the total
To determine further whether vitamin D2 interfered with vitamin D3
metabolism, we gave one group of subjects 500 IU vitamin D2 mixed with
500 IU vitamin D3. The rise in the total 25(OH)D was identical to that
observed for the groups who received either 1000 IU vitamin D2 or 1000
IU vitamin D3 daily, and the total 25(OH)D levels at the end of the
study were no different in all three groups (P = 0.957) (Fig. 1).
An analysis of the 25(OH)D2 and 25(OH)D3 also demonstrated a comparable
increase in both levels in the group that received the combination of
500 IU vitamin D2 (5.7 ± 4.5 ng/ml) and 500 IU vitamin D3 (6.1 ± 4.3
ng/ml) (Fig. 2C).
Many multivitamin preparations and some foods are fortified with
vitamin D2. Two recent observations have raised questions as to whether
vitamin D2 should be used either as a pharmaceutical agent or as a
supplement because it appeared that vitamin D2 not only was less
effective than vitamin D3 in maintaining 25(OH)D levels
but that it also had a negative effect on 25(OH)D status.
There has also been concern that vitamin D2 may not be bioequivalent to
vitamin D3 in maintaining bone health.
The Food and Nutrition Board has recommended that adults up to the
age of 50 yr require 200 IU vitamin D/d, whereas adults 51–70 yr and 71
yr and older require 400 and 600 IU/d, respectively.
However, many experts now agree that in the absence of adequate sun
exposure, at least 1000 IU vitamin D/d is required to maintain 25(OH)D
in the sufficient range.
Because the placebo group did not demonstrate any change in their
circulating levels of 25(OH)D, there was little influence of
environmental sun exposure or dietary or supplemental vitamin D intake
on their vitamin D status. Subjects who received 1000 IU vitamin D2 or
1000 IU vitamin D3 daily gradually increased blood levels of 25(OH)D to
the same levels throughout the study. The increase from baseline in the
total 25(OH)D levels at the end of the study was 9.3 ng/ml for the
vitamin D3 group, 9.9 ng/ml for the vitamin D2 group, and 8.2 ng/ml for
the vitamin D2 plus vitamin D3 group, which is consistent with the
observation that serum 25(OH)D levels increased by 1 ng/ml for every 100
IU vitamin D3.
However, the 25(OH)D levels did not rise above 30 ng/ml, which is now
considered to be the vitamin D-sufficient range, suggesting that more
than 1000 IU vitamin D2 or vitamin D3 is necessary to maintain serum
25(OH)D levels above 30 ng/ml when the sun provides no vitamin D3.
Armas et al.
reported that a single dose of 50,000 IU vitamin D2 was less effective
than 50,000 IU vitamin D3 in maintaining serum 25(OH)D levels over the
ensuing 30 d in the summer. Furthermore, when compared with the group
that received placebo, the group that received 50,000 IU vitamin D2 had
a significant reduction in serum 25(OH)D at the end of the study. We did
not observe any negative influence of vitamin D2 on either total 25(OH)D
or 25(OH)D3 levels (Figs. 1
The maintenance of the serum 25(OH)D3 levels observed in this report
was most likely due to the release of vitamin D3 stored in the body fat
because skin synthesis of vitamin D3 does not occur during the winter in
It is possible that a single pharmacological dose of vitamin D2 enhanced
the destruction of both vitamin D2 and vitamin D3 and their 25-hydroxy
derivatives. However, when 50,000 IU vitamin D2 was given weekly for 8
or twice a week for 5 wk,
there was on average a 100% increase in serum 25(OH)D levels
and a significant increase in bone mineral density in both the hip and
Thus, vitamin D2 when given in pharmacological doses is effective in
maintaining serum 25(OH)D levels and is beneficial for skeletal health.
Why Trang et al.
observed that the daily dosing of 4000 IU vitamin D3 for 2 wk was 1.7
times more effective in raising blood levels of 25(OH)D (increased 9.0 ±
2 ng/ml) than 4000 IU vitamin D2/d (increased 4.2 ± 2 ng/ml) is unclear
at this time. The rise in serum 25(OH)D3 was only about 20% of what
would have been expected for a 4000 IU dose, i.e. 40 ng/ml. This
may be due to their ethanol formulation. This could also be due to the
short time course because we observed that 25(OH)D levels did not begin
to plateau until 6 wk. When vitamin D2 was combined with vitamin D3,
there was no significant difference in the rise in 25(OH)D (Fig. 1).
Furthermore, the group that received 1000 IU vitamin D2 had no
significant change in the level of 25(OH)D3, suggesting that vitamin D2
at least at 1000 IU/d had no influence on the catabolism of vitamin D3
or 25(OH)D3. Thus, 1000 IU vitamin D2/d is as effective as vitamin D3 in
maintaining 25(OH)D status. These observations are consistent with those
of Markestad et al.
and Rapuri et al.
who observed that vitamin D2 and vitamin D3 contributed equally to serum
25(OH)D levels in mothers and their neonates and elderly women,
respectively. Furthermore, the concentrations of 1,25-dihydroxyvitamin
D2 and 1,25-dihydroxyvitamin D3 were reported to be proportional to the
distribution of 25(OH)D2 and 25(OH)D3,
implying that the 25(OH)D-1-hydroxylase (CYP27B-1) recognized 25(OH)D2
equally as well as 25(OH)D3. Therefore, collectively, these data and our
results suggest that vitamin D2 is as effective as vitamin D3 in
sustaining both 25(OH)D and 1,25(OH)2D levels
and improving bone health.
More studies are needed to determine whether the carrier (i.e.
ethanol vs. oil vs. lactose) that vitamin D2 and vitamin
D3 are dissolved in influence either their bioavailability or
catabolism. Our observations also suggest that 1000 IU vitamin D2 or
vitamin D3 is required to sustain blood levels of 25(OH)D above a mean
of 20 ng/ml but was insufficient in raising the levels above a mean of
We thank Lindsey Minion, Bernadette Folly, Thomas Peeples, Sr.,
Horace Shearer, Johanna Gusman, Tarma Johnson, and Deborah Lancaster for
their help with the study; Tim Heeren for his statistical acumen; and
Donna Gendron and Lorrie MacKay for their secretarial assistance.
This work was supported by National Institutes of Health Grant
M01RR00533 and The Beverage Institute for Health and Wellness, a
Division of The Coca-Cola Co., Atlanta, GA.
Disclosure Statement: M.F.H. is on the Speaker’s Bureau for Merck,
Proctor and Gamble, and Eli Lilly and a consultant for Amgen, Novartis,
Quest Diagnostics, Proctor and Gamble, and Merck. R.M.B., T.C.C., E.K.K.,
A.Y., D.B., W.S., A.A., and A.D.T. have nothing to declare. R.R. is
Medical Director of Quest Diagnostics/Nichols Institute and has equity
interests in Quest Diagnostics/Nichols Institute.
First Published Online December 18, 2007
Abbreviation: 25(OH)D, 25-Hydroxyvitamin D.
Holick MF 2007 Vitamin D deficiency. N Engl J Med
Eliot MM, Park EA 1938 Rickets. In: Brennemann’s practice
of pediatrics. Vol. 1. Hagerstown, MD: WF Prior; 1–110.
Holick MF 2006 Resurrection of vitamin D deficiency and
rickets. J Clin Invest 116:2062–2072.
Jeans PC 1950 Vitamin D. JAMA 143:177–181.
Dusso AS, Brown AJ, Slatopolsky 2005 Vitamin D. Am J
Physiol Renal Physiol 289:F8–F28.
DeLuca H 2004 Overview of general physiologic features
and functions of vitamin D. Am J Clin Nutr
Selye, H 1932 On the stimulation of new bone-formation
with parathyroid extract and irradiated ergosterol.
Trang HM, Cole DEC, Rubin LA, Pierratos A, Siu S, Vieth R
1998 Evidence that vitamin D3 increases serum 25-hydroxyvitamin
D more efficiently than does vitamin D2. Am J Clin Nut
Armas LAG, Hollis B, Heaney RP 2004 Vitamin D2 is much
less effective than vitamin D3 in humans. J Clin Endocrinol
Holick MF, Siris ES, Binkley N, Beard MK, Khan A, Katzer JT,
Petruschke RA, Chen E, de Papp AE 2005 Prevalence of vitamin
D inadequacy among postmenopausal North American women receiving
osteoporosis therapy. J Clin Endocrinol Metab 90:3215–3224.
Glendenning P 2002 Vitamin D deficiency and multicultural
Australia. Med J Aust 176:242–243.
Standing Committee on the Scientific Evaluation of Dietary
Reference Intakes Food and Nutrition Board, Institute of
Medicine 1999 Dietary reference intakes for calcium,
phosphorus, magnesium, vitamin D and fluoride. Washington, DC:
National Academy Press.
Vieth R, Bischoff-Ferrari H, Boucher BJ, Dawson-Hughes B,
Garland C, Heaney RP, Holick MF, Hollis BW, Lamberg-Allardt C,
McGrath JJ, Norman Aw, Scragg R, Whiting SJ, Willett WC,
Zittermann A 2007 The urgent need to recommend an intake of
vitamin D that is effective. Am J Clin Nutr 85:649–650.
Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ
2003 Human serum 25-hydroxycholecalciferol response to extended
oral dosing with cholecalciferol. Am J Clin Nutr 77:204–210.
Malabanan A, Veronikis IE, Holick MF 1998 Redefining
vitamin D insufficiency. Lancet 351:805–806.
Adams JS, Kantrorovich V, Wu C, Javanbakht M, Hollis BW
1999 Resolution of vitamin D insufficiency in osteopenic
patients results in rapid recovery of bone mineral density. J
Clin Endocrinol Metab 84:2729–2730.
Markestad T, Aksnes L, Ulstein M, Aarskog D 1984
25-Hydroxyvitamin D and 1,25-dihydroxyvitamin D of D2 and D3
origin in maternal and umbilical cord serum after vitamin D2
supplementation in human pregnancy. Am J Clin Nutr 40:1057–1063.
Rapuri PB, Gallagher JC, Haynatzki G 2004 Effect of
vitamins D2 and D3 supplement use on serum 25(OH)D concentration
in elderly women in summer and winter. Calcif Tissue Int
Clemens TL, Zhou XY, Myles M, Endres D, Lindsay R 1986
Serum vitamin D2 and vitamin D3 metabolite concentrations and
absorption of vitamin D2 in elderly subjects. J Clin Endocrinol
Hartwell D, Hassager C, Christiansen C 1987 Effect of
vitamin D2 and vitamin D3 on the serum concentrations of
1,25(OH)2D2 in normal subjects. Acta Endocrinol (Copenh)
Return to Health & Nutrition Articles
Fair Use Notice: This document may contain copyrighted material whose use has not been specifically authorized by the copyright owners. We believe that this not-for-profit, educational use on the Web constitutes a fair use of the copyrighted material (as provided for in section 107 of the US Copyright Law). If you wish to use this copyrighted material for purposes of your own that go beyond fair use, you must obtain permission from the copyright owner.