There are some misconceptions about Vitamin D2
(And repeating these misconceptions often does not make them accurate)
Just to clarify:
There are two types of vitamin D:
Vitamin D3 - cholecalciferol; is derived from animals (usually from sheep's wool or fish oil). It is the preferred form that is usually recommended as studies have shown it to be more effective, and it is the form animals (including humans) synthesize from sunlight.
Vitamin D2 - ergocalciferol; a plant chemical that is the form synthesized by plants. It has vitamin D activity in humans, but not as much activity as D3;
While D3 has been shown to be more effective (some studies have estimated it to be about 3- 10x more effective) it doesn't mean that D2 is ineffective.
If you are avoiding animal products, and are unable to get enough Vit D from exposure to sunlight, a Vit D2 supplement may be a solution, but you may have to take more of it, or take it more often.
The reason is that in a study done in 2004, subjects were given one dose of 50,000 IU of vitamin D2 or vitamin D3. Vitamin D2 was absorbed just as well as vitamin D3. However, after three days, blood levels of 25(OH)D decreased rapidly in the subjects who were given vitamin D2 and by 14 days they had fallen to the original level. Those who received vitamin D3 sustained high levels for two weeks before dropping gradually. This seems to indicates that vitamin D2 needs to be taken at least every three days to maintain adequate blood levels.
Quoting from the study..
The relative potencies of vitamins D(2) and D(3) 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-hydroxyvitamin 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 3 d, but 25OHD continued to rise in the D(3)-treated subjects, peaking at 14 d, whereas serum 25OHD fell rapidly in the D(2)-treated subjects and was not different from baseline at 14 d.
(Armas LA, Hollis BW, Heaney RP. Vitamin D2 is much less effective than vitamin D3 in humans. J Clin Endocrinol Metab. 2004 Nov;89(11):5387-91.)
Here are a few more studies with relevant info
Eur J Clin Nutr. 2006 May;60(5):681-7. Vitamin D2 dose required to rapidly increase 25OHD levels in osteoporotic women. Mastaglia SR, Mautalen CA, Parisi MS, Oliveri B.
OBJECTIVE: Assessment of the effectiveness and safety of high daily 125 microg (5,000 IU) or 250 microg (10,000IU) doses of vitamin D(2) during 3 months, in rapidly obtaining adequate 25 hydroxyvitamin D (25OHD) levels.
DESIGN: Longitudinal study.
SUBJECTS: Postmenopausal osteopenic/osteoporotic women (n = 38 ) were studied during winter and spring. Median age (25-75th percentile) was 61.5 (57.00-66.25) years, and mean bone mineral density (BMD) was 0.902 (0.800-1.042)g/cm(2). Subjects were randomly divided into three groups: control group (n=13): no vitamin D(2), 125 mug/day (n=13) and 250 microg/day (n=12) of vitamin D(2) groups, all receiving 500 mg calcium/day. Serum calcium, phosphate, bone alkaline phosphatase (BAP), C-telopeptide (CTX), 25OHD, mid-molecule parathyroid hormone (mmPTH), daily urinary calcium and creatinine excretion were determined at baseline and monthly.
RESULTS: For all subjects (n=38 ), the median baseline 25 hydroxyvitamin D (25OHD) level was 36.25 (27.5-48.12) nmol/l. After 3 months, 8% of the patients in the control group, 50% in the 125 microg/day group and 75% in the 250 microg/day group had 25OHD values above 85 nmol/l (34 ng/ml). Considering both vitamin D(2) groups together, mmPTH and BAP levels diminished significantly after 3 months (P<0.02), unlike those of CTX. Serum calcium remained within normal range during the follow-up.
CONCLUSIONS: The oral dose of vitamin D(2) required to rapidly achieve adequate levels of 25OHD is seemingly much higher than the usual recommended vitamin D(3) dose (20 mug/day). During 3 months, 250 microg/day of vitamin D(2) most effectively raised 25OHD levels to 85 nmol/l in 75% of the postmenopausal osteopenic/osteoporotic women treated.
J Steroid Biochem Mol Biol. 2004 May;89-90(1-5):601-4.Effect of Vitamin D supplement use on serum concentrations of total 25OHD levels in elderly women.
Concluded: Vitamin D deficiency was less prevalent in elderly women taking Vitamin D(2) supplements (1.8%) compared to women not taking any supplements (12%).
Calcif Tissue Int. 2004 Feb;74(2):150-6. Epub 2003 Dec 5. Effect of vitamins D2 and D3 supplement use on serum 25OHD concentration in elderly women in summer and winter.
Concluded: In elderly subjects, both vitamin D2 and Vitamin D3 supplements may contribute equally to circulating 25OHD levels, with the role of vitamin D supplement use being more predominant during winter
Vit D2 is effective and further verified here.
More info and a great article on the topic from one of the worlds leading researchers on this topic
"Michael F. Holick, PhD, MD, is professor of medicine, physiology, and biophysics; director of the General Clinical Research Center; and director of the Bone Health Care Clinic and the Heliotherapy, Light, and Skin Research Center at Boston University Medical Center." The below interview is in a free full-text paper.
ALTERNATIVE THERAPIES, May/jun 2008, VOL. 14, NO. 3, 64-75.
Conversations: Michael Holick, PhD, MD.
MICHAEL HOLICK, PHD, MD: VITAMIN D PIONEER.
Interview by Frank Lampe and Suzanne Snyder. Photography by David Keough.
http://www.alternative-therapies.com/at ... erview.pdf
MICHAEL HOLICK, PHD, MD: VITAMIN D PIONEER
ALTERNATIVE THERAPIES, May/jun 2008, VOL. 14, NO. 3
ATHM: Has recent research shown that both vitamin D 2 and D3 are equally effective at increasing the levels of 25-hydroxyvitamin D? This is in opposition with earlier studies, is it not?
Dr Holick: Thatâ€™s correct.
There was a study done in Canada in which researchers gave a group of adults 4000 IU of vitamin D 2 or 4000 IU of vitamin D 3 in ethanol for a period of 2 weeks and showed wide variability, and there appeared to be a 50% reduction in the 25-hydroxyvitamin D levels in the adults who were taking vitamin D 2. This implied that vitamin D2 was less effective than vitamin D 3. The second study that set this kindling on ﬁ re was the observation by Dr Heaneyâ€™s group. They gave a single 50 000-IU dose of vitamin D 2 or a single 50 000-IU dose of vitamin D3 to healthy adults in the summertime. When they followed their 25-hydroxyvitamin D levels, they found that the levels more rapidly declined in the group that got that single dose of vitamin D 2. But more importantly and alarmingly was that the 25-hydroxyvitamin D 3 in those same subjects more rapidly declined than the subjects who received a placebo, implying that the vitamin D 2 induced the destruction of vitamin D 3. Therefore, not only was vitamin D 2 less active, but it caused the destruction of vitamin D3.
I decided to conduct a study in which we gave 1000 IU of Vitamin D 2 or 1000 IU of vitamin D3 to healthy adults at the end of the winterâ€”Dr Heaneyâ€™s study was done in the summer, and sun exposure may have inﬂ uenced the outcome of the study. We found that vitamin D 2 raised the blood levels of 25-hydroxyvita-min D identically to the group that took vitamin D 3. More importantly, to leave no stone unturned, we also made a capsule that contained 500 IU of vitamin D 2 and 500 IU of vitamin D 3 and showed that the 25-hydroxyvitamin D levels increased exactly the same degree for the 25-hydroxyvitamin D 2 and 25-hydroxyvitamin D 3 and that there was no alteration in the 25-hydroxyvitamin D 3 levels in the group that got vitamin D 2.
That, to me, proves that vitamin D 2 is as effective as vitamin D 3 in raising and maintaining 25-hydroxyvitamin D levels.