January 02, 2008
Vitamin D Forms D2 And D3 Work Equally Well

If you've been persuaded (certainly I've tried) that you need more vitamin D maybe (but probably not) you've wondered what form of vitamin D you should take. Well renowned vitamin D researcher Michael Holick, PhD, MD, basically has found that you can take vitamin D as D2 or D3 without worrying which is more potent.

Boston, MA— Researchers from Boston University School of Medicine (BUSM) have found that vitamin D2 is equally as effective as vitamin D3 in maintaining 25-hydroxyvitamin D status. The study appears online in the December 2007 issue of the Journal of Clinical Endocrinology & Metabolism.

Researchers studied healthy adults aged 18-84 who received either placebo, 1,000 International Units (IU) of vitamin D3, 1,000 IU of vitamin D2, or 500 IU of vitamin D2 plus 500 IU of vitamin D3 daily for three months at the end of winter to establish what effect it had on circulating levels of total 25 (OH)D as well as 25(OH)D2 and 25(OH)D3. Sixty percent of the adults were vitamin D deficient at the start of the study.

Adults who received the placebo capsule daily for three months demonstrated no significant change in their total 25(OH)D levels during the winter and early spring. Adults who ingested 1,000 vitamin D2/d gradually increased their total 25(OH)D levels during the first six weeks. Adults who ingested 1,000 IU of vitamin D3 had a baseline 25(OH)D that was statistically no different from the baselines of either the placebo group or the groups that took 1,000 IU of vitamin D2/d or 500 IU vitamin D2 plus 500 IU vitamin D3/d. The vitamin D3 group increased their serum 25(OH)D levels similar to that of the group that ingested vitamin D2.

The circulating levels of 25-hydroxyvitamin D increased to the same extent in the groups that received 1,000 IU daily as vitamin D2, vitamin D3, or a combination of 500 IU vitamin D2 and 500 IU vitamin D3. The 25-hydroxyvitamin D3 levels did not change in the group that received 1,000 IU vitamin D2 daily. One thousand IU of vitamin D2 or vitamin D3 did not raise 25-hydroxyvitamin D levels in vitamin D deficient subjects above 30 ng/ml.

Even if you haven't wondered about this particular burning vitamin D research question at least this serves as a reminder that vitamin D probably will reduce your odds of cancer, auto-immune disorders, infections, osteoporosis, and assorted other maladies.

Share |      Randall Parker, 2008 January 02 10:02 PM  Aging Diet Studies

drtomcor said at January 3, 2008 7:30 AM:

The important finding is that 1000 units/day couldn't get the Vitamin D level above 30ng/ml. Fortunately, it is a low cost item in either D2 or D3 form. The desired level is 50-60 ng/ml.

S said at January 3, 2008 9:59 AM:

D2 vs D3, oil-based cap vs powdered tablet, now this. ARGH! I'll be getting my Vit D (2 or 3, whichever) from the sun while bicycling and gardening, and from cod liver oil capsules during the few cold spells we have on the 29th latitude until they figure this stuff out.

FCH said at January 3, 2008 10:36 AM:

FYI, I had my 25-hydroxy vitamin D level checked five months ago and it was 17, should be around 50.

I live in South Calif and bike/hike every weekend.

I took 2000 units of vitamin D per day for five months and just had my level rechecked. It had moved up from 17 to 27.

I'm now taking a once weekly 50,000 unit pill for 8 weeks, plus my usual 2000 units per day.

Bottom line, get tested to really know what your level is.

Brett Bellmore said at January 3, 2008 6:24 PM:

I've ordered a bottle of Nordic Naturals' "Arctic-D" cod liver oil. Should handle the Omega 3 and vitamin D issues at the same time. Sounds like I ought to hit the doc up for a blood test after I've been on it a little while, though.

Peter knopfler said at January 3, 2008 6:30 PM:

I personally find that Sunlight vitamin D through the skin is very different than vitamin D run through the digestive tract. Born in Vienna, educated in Canada, however after my degree I moved to Hawaii because of the amount, and angle of sunlight. 20 years in Hawaii, hours in the Sun,did a film in Puerto Vallarta, and in doing so, I noticed my cells felt at home, check the globe, sure enough tropic of Cancer. 10 years in Vallarta, got restless now live in Cancun, again angle of sunlight. I go to my roof, sun naked for one and half hours daily, all one color now, and feeling good. I feel like the Son of the Sun, never a thought of skin cancer, no one can beleive my age, I just look and act half my age, for many it might not be possible for me the sun is better than vitamin D supplement, your skin absorbes information from the sun, you can't get that from a pill. I'm 58 years old, sunning the last 40 years no problems, so I will continue my relationship to the sun, permanent tan for me, don't be shy google my name Peter Knopfler. Thankyou.

Jim Wint said at January 4, 2008 12:04 AM:

Here is another medical study that reaches the opposite conclusion.

Vitamin D2 Is Much Less Effective than Vitamin D3 in Humans
Creighton University (L.A.G.A., R.P.H.), Omaha, Nebraska 68131; and Medical University of South Carolina (B.W.H.), Charleston, South Carolina 29425


The Journal of Clinical Endocrinology & Metabolism 89(11):5387–5391
Copyright © 2004 by The Endocrine Society
doi: 10.1210/jc.2004-0360

Moderate exposure to UV light (sunlight or in a tanning bed) on skin is the best source of vitamin D3.

A single tanning bed session can process 15,000IU of healthy natural vitamin D3.

Jim said at January 4, 2008 12:11 AM:

Be careful not to overdose on cholcalciferol (vitamin D3), also known as rat poison.

It is better to get your vitamin D naturally from moderate exposure to UV light.

drtomcor said at January 4, 2008 6:44 AM:

Some thoughts:

The sun may deliver other benefits beyond Vitamin D, but of course don't overdo it.

Cod liver oil not a good way to get Vitamin D because the Vitamin A component is much higher and toxicity is a real possibility with that.

Toxicity with Vitamin D almost unknown. Consider that 30-45 minutes in midday sun helps you produce 30,000 units without any ill effects.

Brett Bellmore said at January 4, 2008 9:22 AM:

According to their reference materials for doctors, that Arctic-D cod liver oil contains, per teaspoon,

1000-2000IU vitamin A
400IU vitamin D
5IU vitamin E
625mg DHA
410mg EPA
225mg other Omega 3s
600mg Oleic acid

So I'll be suplementing it with pure Vitamin D, rather than trying to take enough of the cod liver oil to get all my vitamin D.

Dr. Edward Gorham said at January 7, 2008 11:29 AM:

Dear Mr. Parker,

This work advances the understanding of the pharmacokinetics of vitamin D2 and vitamin D3 metabolism; however it does not provide a basis for assuming that vitamin D2 has equivalency with vitamin D3 with respect to cancer or chronic disease prevention. The study interprets the increase in serum 25-hydroxyvitamin D2 or 25-hydroxyvitamin D3 as equivalent endpoints. The fact is that the metabolites of vitamin D2 and vitamin D3 are different molecules. Animals have evolved to use vitamin D3, and serum 25-hydroxyvitamin D3 is the biomarker that varies by sun exposure and latitude. Geographic studies of latitude and sun exposure have found reduced risk of colon cancer, breast cancer, diabetes and other cancers and chronic diseases at low latitudes with high levels of sun exposure. This protective association is based on the photosynthesis of 25-hydroxyvitamin D3 that results from sun exposure. This study found an elevation of two distinct intermediate biomarkers resulting from a dosing regime with two different forms of vitamin D. It does not demonstrate the equivalency of these compounds for prevention of colon cancer, breast cancer, multiple sclerosis, diabetes or other chronic diseases. Reduced risk of these diseases is associated with a daily intake of 2,000 IU of vitamin D3.

Edward D. Gorham, M.P.H, Ph.D.
Assistant Professor,
Dept of Family and Preventive Medicine
San Diego, CA 92186-5122

Edward Hutchinson said at January 15, 2008 1:57 AM:

I would like to point out that D2 is often considerably more expensive than D3. So on a cost per effective IU basis should be the preferred choice.
Vitamin D2 rip-offs http://heartscanblog.blogspot.com/2007/11/vitamin-d2-rip-offs.html

Gail Renee said at February 8, 2008 11:16 AM:

I am totally confused. Can someone please tell me why Michael Holick, considered a D2/D3 guru and the "author" of the study above, also signed this letter http://www.grassrootshealth.org/_download/vitamin_d_consensus_letter_090907.rtf?
It is a letter by Dr Gorham above, who left a comment above regarding D3's superiority over D2. Dr Holick states D2 and D3 to be equivalent but then signed the letter by Dr Gorham that D3 is superior? I am trying to decide whether or not to take a whopping does of D2 as prescribed by my dr for D deficiency and can't seem to get a straight answer.
Whew, thanks for any feedback. I have been on this thing for days now and thought Dr Holick's article finally gave me my answer only to see that Dr Gorham and Dr Holick (time frames may play in here) as well state D2 does not attack the issue of cancers which all of us are greatly trying to avoid.
Feedback would really be appreciated...

Itsme said at May 23, 2008 11:05 AM:

If you research it you will find that most recent studies show that D3 is superior to D2. Spend an hour in google and find your own answers. Look for medical journal articles, not popular websites.

Please note that Dr. Gorhams states that 2000 IU per day is the level associated with reduced disease risk. If you are deficient then you will need to take more than that until your body gets to a normal level.

In my case, my level tested to be 18 (not sure what the units are). After six months of taking 2000 IU per day my level had only increased to 24, and I live in the South of the USA. I then started to take 5000 IU per day and 3 months of that raised my level to 38. It has been almost 6 months and I have continued to take 5000 IU per day. I will be tested again soon and I expect that my level will be between 50 and 55.

Once I verify that my level is that high then I will start taking a 2000 IU vitamin D on one day and a 5000 IU the next. I assume that is what I will need to maintain my levels. I'll get tested again in 3 months and verify that and make any needed adjustments.

TERNER said at June 16, 2008 12:49 PM:

My doctor (via the MA) said that I need to increase my VIT D after reviewing blood tests.
He recommended 800-1200 iu a day -- but my question is that Vit D or Vitamin D3

Is one better than the other

The local phamacist said D3 is active... but said the doctor would know more
The MA suggest the Pharmacist would know more

Can someone define the difference between D and D3?

scott said at October 20, 2008 4:14 PM:

Has anyone noticed a significant change in overall health since supplementing with D?
Please reply in detail if possible.

Mary said at August 10, 2009 10:46 AM:

My doctor put me on cod liver oil 2 1/2 years ago. After taking it for about 6 months I reported to him that all of my skin tags were gone. I have had them for years. I also have psoriasis. The cod liver oil did reduce the size of most of the patches but did not take them away. I had a couple of moles on my back that just fell off after taking the cod liver oil for about 2 years. My toe nails and finger nails had a fungus that I tried everything to get rid of it. Nothing worked. All of my nails from the cuticle about 3/4 of the way to the tips are healthy now. I am assuming that when they grow all the way out they will be healthy. The thing about cod liver oil, for me that is, is to take it everyday without fail. I am a procrastinator and usually do not stay with anything long term. I take 1 in the summer months and 2 in the winter months. I also have some kind of herpes virus on the very lowest part of my back, near my tail bone (doctor first thought it to be shingles). The out break had been there for about six years. Not off and on but continuously. After I started taking the cod liver oil it has been under control. Still have break out on occasion, but there gone within 24 hours. I just take an extra cod liver oil pill. My doctor says "I don't know if cod liver oil did all of that". I might add I have not even had a cold, a runny nose or even a cough of any kind. This is my testimony about cod liver oil. I try to encourage my children to give this to their children and so fourth. In my opinion the key is to take it on a consistent basis, and it is awesome for the immune system.

Brian said at November 4, 2009 11:36 AM:

The problem with this study is that everyone was taking vit. D of either kind daily. Thus it is obvious that both would maintain (key word here) calcidiol levels. What should have been tested was the levels of vit. D after a SINGLE large dose of D2 or D3, a month or so later. As it stands, this test proves nothing.

Dr. Thomas Anderson said at November 19, 2009 10:03 PM:

Vitamin D in supplement form is not the same as the vitamin D we get from sunshine -- particularly the non-fat forms of the vitamin found in pills and added to milk -- and the effects on health are entirely different. Vitamin D from sunshine is strongly protective against cancer, for example, whereas vitamin D supplements can actually increase the risk. Here is one of the more recent studies showing an increased risk for prostate cancer:


The vitamin D we make from sunlight exposure is stored in our body tissues and utilized when needed. Contrary to the position taken by Holick in the past few years, deficiency is quite rare -- even in the far north -- and thus supplements are not really needed. They can do a lot more harm than good.

Dr. Thomas Anderson said at November 19, 2009 10:09 PM:

Vitamin D in supplement form is not the same as the vitamin D we get from sunshine -- particularly the non-fat forms of the vitamin found in pills and added to milk -- and the effects on health are entirely different. Vitamin D from sunshine is strongly protective against cancer, for example, whereas vitamin D supplements can actually increase the risk. Here is one of the more recent studies showing an increased risk for prostate cancer:


The vitamin D we make from sunlight exposure is stored in our body tissues and utilized when needed. Contrary to the position taken by Holick in the past few years, deficiency is quite rare -- even in the far north -- and thus supplements are not really needed. They can do a lot more harm than good.

France said at February 18, 2010 12:53 PM:

What is a vegan from the PNW supposed to do??? Vitamin D3 isn't vegan, I'm a fair-skinned northerner who burns sitting too near a light bulb, and we don't get any sun here anyway! I'm stuck with D2 or nothing, unless someone knows of another alternative? Is there a vitamin D1? D4?

JeffieFreedom said at May 12, 2010 11:50 PM:

Contrary to Brian's comments this study was relevant BECAUSE these people were taking vitamin D every day at the dose which is normal for a daily supplement. And the result here shows it works just fine. Which is why virtually all the Health agencies of English speaking nations in the Western world are still advocating fortification of common foods with small amounts of either of the D vitamins (I'm not suggesting anything about non-English speaking nations, it's just that I can't read what their governments recommend). There is another study which was done where they gave the subjects one near toxic dose of vitamin D and they noticed that D3 persisted significantly longer in their system than D2, but that kind of vitamin D dosing could actually cause more harm than good (look up vitamin D overdosing on the wiki, it does all sorts of bad things to your arteries). It looks to me like this is the relevant study to read for those interested in supplementing.

Kirkman Dixon said at November 12, 2010 7:44 PM:

"Equally as effective as" is redundant. Drop the "equally" and you're writing proper English..."as effective as."

Randall Parker said at November 13, 2010 8:38 PM:

Kirkman Dixon,

Speaking as a blogger the clarity of whose every post gets tested by the comment feedback: I find redundancy necessary in communication. I find I have to say things more than one way and really hammer on a point so that people do not react to something I didn't even say.

Post a comment
Name (not anon or anonymous):
Email Address:
Remember info?

Go Read More Posts On FuturePundit
Site Traffic Info
The contents of this site are copyright ©