Vitamin D2 vs. vitamin D3

An interesting question came up on the Track Your Plaque Member Forum about vitamin D2 vs. vitamin D3. This often comes up among our patients, as well.

Vitamin D is measured in the blood as 25-OH-vitamin D and is distinct from 1,25-diOH-vitamin D, a kidney measure, a test you do not need unless you have kidney failure.

The human form of vitamin D is cholecalciferol and is usually obtained via activation of a precursor molecule in the skin on activation by the sun. You can also take cholecalciferol and it increases blood levels of 25-hydroxy vitamin D reliably.

However, there is a cheap, plant-sourced, alternative to vitamin D3, called vitamin D2, or ergocalciferol. D2 has far less effect in the body. Taking D2 or ergocalciferol orally is an extremely inefficient way to get D. Unfortunately, it's the form often used in milk and many supplements, even the prescription form of D. About half the multivitamins and calcium supplements I've looked at contain ergocalciferol rather than cholecalciferol.

Taking vitamin D2 yields very little conversion to the effective D3. This particular issues is maddening, as the USDA requires dairy farmers to add 100 units of vitamin D to milk, and D2 is often used. In other words, the D in many dairy products barely works at all. There are many children who rely on D from dairy products who are at risk for rickets and are not getting the D they need from dairy products because of this cost-saving switch. Do not rely on milk for vitamin D for your children.

D2 or ergocalciferol is often included in the blood measures of vitamin D along with vitamin D3. The only reason it's checked with blood work is to ensure "compliance,", i.e., see whether or not you're taking a prescribed ergocalciferol. Beyond this, it has no usefulness.

25-OH-vitamin D3, or cholecalciferol, is both the blood measure and the supplement you need. This is the one that packs all the punch. Keep in mind also that it is the oil-based gelcap you want, with more consistent and efficient absorption. Tablets usually barely work at all, even if it contains cholecalciferol. Most people who take calcium tablets with D, or multivitamin with D, not only are getting a powdered form of D, but also in trivial doses. It's the pure vitamin D3, cholecalciferol, in gelcap form you want if you desire all the spectacular benefits of vitamin D.

Comments (21) -

  • Jim Wint

    4/26/2007 1:35:00 PM |

    It's good that you explained how vitamin D3 is better than vitamin D2.

    Your readers should also know that, depending on their skin type, just one or two sessions in a tanning bed will produce all the healthy vitamin D3 a human body can use.

    Moderate tanning is healthy behavior.  Don't sunburn.

  • Anonymous

    4/26/2007 3:36:00 PM |

    Dr. Davis, your blogs on vitamin D are terrific.  I am a colleague of Dr. John Cannell, and am presently coauthoring a book with him.  It will deal with the effect of vitamin D supplementation on athletic performance.  He has also endorsed my current book on the health benefits of sunlight and vitamin D.  If you would like a free copy of that book--Solar Power for Optimal Health--please contact me at or call me at 435-628-3102.  

    Keep up the good work!

    Marc Sorenson, EdD

  • Darwin

    5/3/2007 9:40:00 PM |

    Re vitamin D consumption, do you have any thoughts re this study?  I'd like to recommend to my parents that they take an oil-based Vit. D supplement (they're in their 70s), but that study gave me pause.

  • Dr. Davis

    5/4/2007 1:09:00 AM |

    Unfortunately, the study was only in abstract form, meaning none of the full details were available.

    Nonetheless, several uncertainties:

    What was the calcium intake? What was the vitamin D intake and what blood level of 25-OH-vitamin D3 was obtained?

    I suspect that few of the participants had even normal vitamin D blood levels. The majority of vitamin D preparations in calcium tablets barely work at all due to poor absorption.

    However, I do worry that, with appropriate D supplementation, the doses of calcium many people take is excessive. The true need for calcium is likely far less when D is fully replenished.

    I would not make any firm judgments based on this preliminary report. Interesting issue, however.

  • Dave Lull

    3/27/2008 3:45:00 AM |

    Hi Dr Davis,

    I'd been persuaded, like you, that D3 is the form of Vitamin D to use for maximum effect.  Now comes this study:

    "Vitamin d2 is as effective as vitamin d3 in maintaining circulating concentrations of 25-hydroxyvitamin d"

    Holick MF, Biancuzzo RM, Chen TC, Klein EK, Young A, Bibuld D, Reitz R, Salameh W, Ameri A, Tannenbaum AD.

    Boston University School of Medicine, 715 Albany Street, M-1013, Boston, Massachusetts 02118.

    J Clin Endocrinol Metab. 2008 Mar;93(3):677-81. Epub 2007 Dec 18.

    Dr Holick uses Vitamin d2 in treating his patients.

    He was recently interviewed on the radio program the People's Pharmacy; the interview is available as a podcast.


  • Anonymous

    6/24/2008 4:31:00 AM |

    where can I buy vitamin D3 in Gel Caps?  Are they readily available?

  • Anonymous

    7/4/2008 9:36:00 PM |

    Google "vitamin d2 tablets".  Loog for softgels, or gelcaps.

  • Anonymous

    7/25/2008 4:45:00 PM |

    Buy Vitamin D3 in softgels (oil based form from

  • Anonymous

    9/21/2008 12:06:00 AM |

    So, if I am buying a supplement that is labeled as Vitamin-D (not D3), but the label says it is 1000 IU of Cholecalciferol, the supplement is really Vitamin D3?

  • Anonymous

    11/18/2008 8:16:00 PM |

    I'm curious why you have no comment on the above story that refutes your entire theory.

  • Anonymous

    12/12/2008 11:56:00 PM |

    Actually your post is very confusing because you say vitamin d3 is 25-oh-d3, actually it's a metabolite of d3, also you say ergocalciferol is inneficient because yields little conversion to 25-oh-d3, but d2 converts ONLY to 25-oh-d2 and very efficiently, and has similar activity to the d3 form(about 2/3 of the potency), the bad about d2 is also that has faster metabolism than d3.
    All in all, d2 is efficient, not like d3, but it's not useless like you say, and d2 has metabolites with potent anticancer activity, similarly to tamoxifen in breast cancer, so d2 has it's own benefits over d3.

  • Alphonzen

    3/19/2009 1:42:00 PM |

    Vitamin D2 Is As Effective As Vitamin D3 In Maintaining Concentrations Of 25-hydroxyvitamin D, Study Suggests

    Sorry blogger, but you have been proven wrong.

  • Anonymous

    9/24/2009 11:21:46 PM |

    The difference as I've understood - there are actually 5 forms of Vitamin D (D1-D5). Vitamin D2 must be converted to be used, Vitamin D3 is used directly. Vitamin D2 is "relatively ineffective" because it is the  stored form and it's stored in the body's fat- which is why it has certain properties that D3 doesn't possess for fatty tissue health. Eventually D2 effectiveness would equal D3 because the body eventually converts what it needs. However, it has requirements for the conversion, and if taken for anti-inflammatory, anti-cytokine storm, immune modulation, then D3 is the much better form since it can be used immediately. When healthy I take D2 and D3 - D2 fills the body's stores while D3 is consumed. When the immune system is being challenged Vitamin D3 is the better form and will keep the D2 levels in the fat unaffected.

    As far as calcium supplementation - I think it's ludicrous - I can't imagine anyone, other than people that cannot tolerate milk products, not getting enough dietary calcium. I think that's one of the biggest myths propagated today. Hypercalcemia, and even just excessive calcium intake, has been shown to cause brain lesions in elderly, and calcium creates issues when Vitamin D is supplemented.   Magnesium supplementation is MUCH more important for everything from healthful bones, heart rhythm and heart attack protection, to smooth muscle relaxation, and mental acuity. We need a MINIMUM of 400mg and should be taking more.  With everyone drinking bottled water that has next to no magnesium content, we are all susceptible to dangerously low "sudden heart attack" levels of magnesium.

  • Anonymous

    11/16/2009 7:21:58 AM |

    Have you studied people who have had gastric bypass / weight loss surgery? They have completely different calcium citrate and vitamin D requirements than a regular person. Please see the web site  There are many professionals on this site with articles on supplementation.

    I buy my supplements from

  • Anonymous

    12/2/2009 6:11:36 PM |

    For vegetarians (where killing of an animal is prohibited) -
    D3 made from lanlolin (sheeps wool) is the only choice, there is no pure plant based D3?

    For Vegans (has to be plant based only)
    Looks like D2 made from yeast is the only choice.
    If any one know best form of D3/D2 suitable for vegetarians/vegans, please post where one can get (Please note, gel capsules are made from animal sources, they would not be suitable). Thank you

  • Steve D'Sa

    2/16/2010 4:27:48 AM |

    I'm taking a vegan calcium supplement, with vitamin D3. Its branded Vitamin Code, RAW CALCIUM, from Garden of Life, its fortified with Magnesium and other things. Its vegan, and RAW. I think the D3 source is algae.

  • Anonymous

    9/8/2010 5:49:49 AM |

    Sorry Steve. The code RAW vitamins you're talking about aren't vegan. They get their D3 "primarily from lanolin" (=occasionally fish?). According to them, since they remove the traces of lanolin during processing, they felt that it was vegan.

    After listening to them go on and on with their justifications of it and why it was vegan, it just felt like a giant marketing scheme. Needless to say, I'm now quite wary of all Garden of Life products.

    Regardless, they're still in the process of changing labels, but in the meantime, nope, not vegan. Frown

  • edegra online

    9/23/2010 6:40:36 AM |

    Thanks for providing the comparison
    between Vitamin D2 and Vitamin D3.

    Best Regards
    Smith Alan

  • buy jeans

    11/3/2010 8:32:37 PM |

    D2 or ergocalciferol is often included in the blood measures of vitamin D along with vitamin D3. The only reason it's checked with blood work is to ensure "compliance,", i.e., see whether or not you're taking a prescribed ergocalciferol. Beyond this, it has no usefulness.

  • Dr Brad

    6/13/2011 5:48:35 AM |

    Case study:  lab result shows Total Vit D, 25-OH 36; D3=6, D2=30.  Person supposedly taking 2000 IU D3 daily.   What is the significance of the D3=6 measurement.  I typically look at total and make recommendation from there but have been told that perhaps I should look at sub-classes. thoughts?

  • Annika Brixner

    5/19/2014 4:34:26 AM |

    Wonderful site. Plenty of useful information here. I am sending it to a few pals ans additionally sharing in delicious. And of course, thank you on your effort!

Emmer, einkorn, and agribusiness

Emmer, einkorn, and agribusiness

10,000 years ago, Neolithic humans did not obtain wheat products from the bagel shop, grocery store, or Krispy Kreme. They obtained wheat by locating a nearby wild-growing field of wild emmer or einkorn wheat grass, then harvesting it with their stone sickles.

Neolithic humans, such as the Natufians of the Fertile Crescent, carried their freshly-cut wheat home, then ground it by hand using homemade mortar and pestle. As yeast-raised bread was still some 5000 years in the future, emmer and einkorn wheat was not used to bake bread, but was consumed as a porridge in bowls. Einkorn has the simplest genetic code of 14 chromosomes, while emmer has 28 chromosomes.

A third variety of wheat appeared on the scene around 9000 years ago, a natural hybridization between emmer and goat grass, yielding the 42-chromosome Triticum aestivum species. Egyptians learned how to cause wheat to rise around 3000 BC, yielding bread, rather than the unleavened flatbreads of their predecessors.

From the original three basic varieties of wheat available to Neolithic man, over the past 30 years wheat has exploded to over 25,000 varieties. Where did the other 24,997+ strains come from?

In the 1980s, thousands of new wheat strains arose from hybridization experiments, many of them conducted in Mexico. Then, in the late 1980s, genetic engineering quietly got underway in which geneticists inserted or deleted single genes, mostly designed to generate specific characteristics, such as height, yield per acre, drought resistance, but especially resistance to various pesticides and weed killers. The fruits of these efforts were introduced into the market in 1994. Most of the genetically modified foods were thought to be only minor modifications of the unmodified original and thus no safety testing in animals or humans was conducted.

We now have many thousands of wheat strains that are different in important ways from original emmer, einkorn, and Triticum aestivum wheat. Interestingly, it has been suggested that einkorn wheat fails to provoke the same immune response characteristic of celiac disease provoked by modern wheat gluten, suggesting a different amino acid structure in gluten proteins. Another difference: Emmer wheat is up to 40% protein, compared to around 12% protein for modern wheat.

In other words, the wheat of earlier agricultural humans, including the wheat of Biblical times, is NOT the wheat of 2010. Modern wheat is quite a different thing with differing numbers of chromosomes, different genes due to human manipulation, varying gluten protein composition, perhaps other differences.

Somewhere in the shuffle and genetic sleight-of-hand that has occurred over the last 30 years, wheat changed. What might have been the "staff of life" has now become the cause of an incredible array of diseases of "wheat" intolerance.

Comments (32) -

  • Anonymous

    5/21/2010 8:38:44 AM |

    I guess the scientists can once again manipulate wheat sorts to a form that may benefit us folks who love toast at breakfast.

  • Anne

    5/21/2010 11:24:05 AM |

    "Emmer wheat is 40% protein, compared to around 12% protein for modern wheat."

    Is that supposed to be 12% for emmer wheat and 40% for modern wheat?

    In Italy Emmer wheat is called faro. Is the ancient emmer wheat the same thing as what is grown today or have we "improved" it?

    There are some ancient grains unrelated to wheat that are used by people with celiac disease. Amaranth and teff are two examples. Indian rice grass used by native Americans is sold under the name Montina.

    All grains raise my blood glucose.

  • arnoud

    5/21/2010 11:47:28 AM |

    Very interesting post. Even when buying supposedly 'unprocessed' foods at the grocery store, we need to keep in mind that there may be little 'natural' about some/many of those foods.   The processing may be in the modified genetics...

    Are the original emmer and einkorn still available somewhere?

  • Meredith

    5/21/2010 12:31:50 PM |

    An absolutely fascinating history!  Is it possible to obtain ungenetically modified Einkorn wheat today?

  • Ned Kock

    5/21/2010 2:56:57 PM |

    Fascinating analysis. This may explain why many people whose ancestors consumed wheat in great quantities do not tolerate wheat well. This happens even though it may not take that long for a food-related trait to evolve (as little as 396 years may be enough):

  • Kathryn

    5/21/2010 3:55:52 PM |

    I love this info.

    But on occasion i wish you would quote your source.  I belong to a health forum where we use stuff like this, but without an original source i can't do much with it.  

    Not to be critical.  I so appreciate all that you take time to share here.

  • shel

    5/21/2010 10:20:28 PM |

    brilliant. thanks for this.

  • shel

    5/21/2010 10:24:15 PM |

    ...incidentally, can you put a search box on this blog?

  • Dr. William Davis

    5/22/2010 12:46:08 AM |

    Hi, Anne--

    No, the emmer is unusually rich in protein.

    Makes you wonder if there is a lesson in that observation. The protein--gluten--differs in structure, also.

  • Dr. William Davis

    5/22/2010 12:47:13 AM |


    I am looking!

    It would be an interesting experiment to consume emmer alongside modern wheat and see what happens. Some people claim that einkorn can be consumed by celiacs safely.

  • Anonymous

    5/22/2010 12:59:17 AM |

    Interesting and thought provoking post. As another commenter said, I do really wish you would quote the source of your information.

  • Kurt N.

    5/22/2010 2:06:28 AM |

    Do you have a reference for the protein content of emmer?  I've heard it was pretty high, but 40% seems off the scale.

  • Anne

    5/22/2010 3:50:13 AM |

    Oops, the high percentage I was thinking of was the percentage of the protein that is gluten.

  • Dr. William Davis

    5/22/2010 12:57:41 PM |

    Source for emmer wheat protein composition:

    Avivi L. High grain protein content in wild tetraploid wheat, Triticum dicoccoides. In Fifth International Wheat Genetics Symposium, New Delhi, India 1978, Feb 23-28;372-80.

    Dr. Shewry of the UK is a great resource:

    Wheat. J Exp Botany 2009; 60(6):1537-53.

  • billye

    5/22/2010 5:05:31 PM |

    Hi Dr. Davis,

    More confusing information for the evolutionary life style advocate to deal with.  This is my simple clarifying statement.  Since wheat in any form, regardless of chromosome content, is not a health supporting evolutionary food, due to the fact that we did not evolved to eat it, should we not avoid it like the plague?  After all, it along with high fructose, and high starch vegetables and fruits are the main cause of most if not all of the diseases of the metabolic syndrome.

    Billy E

  • Anonymous

    5/22/2010 9:35:37 PM |

    Source for organically grown emmer:

  • Santiago

    5/23/2010 12:40:46 AM |

    Something similar most happen with the corn we eat here (Colombia), as it causes very little blood sugar raise no where close to what you describe when you talk about corn bread

  • Stan Ness

    5/23/2010 8:05:20 AM |

    Great post on einkorn and emmer you have provided here. Thanks for sharing.  I've been following the research on einkorn for some time now.  More and more, I see that einkorn has many health benefits that our modern wheat lacks.  You are right on when you call it a "genetic slight-of-hand".  Well said!  I found some research about antioxidants in einkorn grain and thought you may also find it interesting.  There's a lot too this stuff!

  • Dr. William Davis

    5/23/2010 2:10:40 PM |

    Thanks for the lead anonymous.

  • Dr. William Davis

    5/23/2010 2:11:16 PM |


    I've perused your Einkorn Blog. Great stuff!

  • billye

    5/23/2010 3:43:47 PM |

    I perused Bluebird as a commenter recommended.  Emmer, einkorn etc, a grain by any other name is still a grain.  One of Bluebird farms offerings says it all. "we offer a variety of gift baskets and boxes filled with fresh milled whole grains and local artisanal honey and syrup."  This is great for those of you that wish to raise your blood sugar and prompt diabetes type 2 along with any number of metabolic syndrome diseases, including Celiac disease.

    Billy E

  • Miki

    5/23/2010 5:26:38 PM |

    It does seems the diploid and tetraploid varieties of wheat are less potent as far as gluten poisoning is concerned: "Mapping of gluten T-cell epitopes in the bread wheat ancestors: implications for celiac disease." (,f1000m,isrctn). A quote from the conclusions: "we found that the fragments identical or equivalent to the immunodominant 33mer fragment are encoded by alpha-gliadin genes on the wheat chromosome 6D and thus absent from gluten of diploid einkorn (AA) and even certain cultivars of the tetraploid (AABB) pasta wheat".

  • Anonymous

    5/24/2010 1:35:10 AM |

    I have some kind of sensitivity to wheat. After reading this post I've been looking arround and found in wikipedia some info saying Durum wheat doesn't cause alergui reaction either.
    Maybe this is why I have so strong reactions to beer, bread and pizza, but I seem to be able to eat pasta with out any problems.
    Maybe this explains a bit of the italian heart health thing, probably most of the wheat they eat is of a healthier kind.

  • Cherry

    5/24/2010 8:20:21 AM |

    Love your blog, not only for your thorough much needed nutritional correlates to CAD, but also your gutsy willingness to expose the truth around big pharma, and greed influencing the practice of medicine.  
    Here in France, Einhorn( Triticum monococcum) has been cultivated since the 9 th millennium BC in a small area of Haute Provence. It is called petit epeautre and it is truly delicious!  It has very little gluten.
    There is much regulation in the cultivation in order to protect the genetic purity of this ancient grain.  Like wines it has a AOC (appelation d'origine controlee) has wonderful information also in english. Each September there is a petit epeautre festival.  It is one grain I allow myself to enjoy occasionally.

  • Dr. William Davis

    5/24/2010 10:39:46 PM |

    Great find, Miki!

    Thanks for the lead.

  • Dr. William Davis

    5/24/2010 10:53:49 PM |

    Hi, Cherry--

    Thank you for pointing me towards the French source.

    While I knew that there was some einkorn or emmer grown in Italy, some in the Middle East, and very little in the U.S., I had difficulty locating it in France.

    It would be interesting to compare the various sources.

  • Anonymous

    7/21/2010 7:29:47 AM |

    As someone (a celiac) who is EXTREMELY interested in introducing ancient and potentially benign wheat ancestors into my diet, I am very curious as to how someone like myself might be expected to react to emmer.  (And by the way, I'm pending reception of some einkorn I've already ordered to see if I can tolerate it.)

    In any case, success stories will be warmly welcomed.  Failure stories not so much, but I would appreciate you please tell them, nevertheless.  The pain is necessary, and it is for all of us to share for our common edification.

  • David Isaak

    8/1/2010 11:16:22 PM |

    Well, I expect a whole host of bricks to come hurtling my way when I say this, but I'm  a low-carber...and one of the things I eat quite frequently is seitan. That's essentially pure wheat gluten (which has long been a staple in Asian cuisines).

    I avoid most grains (other than flaxseed), but I don't avoid grain proteins. I sometimes wonder if all the wheat problems people report are really from the gluten proteins. Funny those problems weren't reported in China over all those centuries...

  • Fredo

    8/3/2010 9:41:19 AM |

    i`m not sure if this was posted here before, but i guess it fits good into the context:

  • Principal Quattrano

    10/3/2010 4:58:07 AM |

    I used to eat a lot of seitan myself, before I had to give up wheat.

    I have heard a great many suggestions as to what celiacs can or ought to be able to eat, but very little evidence that such things are truly safe for one who reacts to gluten. A lot of common knowledge is based on nothing but oft-repeated rumors.

    Before giving up gluten, I purchased some farro in an Italian grocery. It was regular wheat. Emmer was not available. Perhaps it is in Italy.

  • Anonymous

    12/22/2010 4:58:51 AM |

    Dr Davis,
    I would like to know your thoughts on Ezekiel bread.  I thought it was better since it's a pure protein and sprouted.  

    I would really appreciate your feedback.


  • Henry North London 2.0

    2/25/2011 12:12:39 AM |

    I've just come across Kamut flour

    This is a tetraploid wheat high in selenium.  Ive bought a couple of lbs of flour to try it out.

    Im hoping that this will restore bread to my diet as I find modern pappy breads made by the CBP really awful,on my digestion and this wheat has higher protein.

    Its much like emmer in that its tetraploid and has been called everything from King Tut wheat to Noahs Flood wheat.