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 |

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When meat is not just meat

When meat is not just meat

The edgy nutrition advocate, Mike Adams, over at came up with this scary photo tour of a processed meat product from Oscar Mayer: Mystery Meat Macrophotography: A NewsTarget PhotoTour by Mike Adams

Along with increasingly close-up photographs of this meat-product, Adams lists the ingredients in Oscar Mayer's Cotto Salami:

Beef hearts
Corn syrup

Contains less than 2% of:
Sodium lactate
Sodium phosphates
Sodium diacetate
Sodium erythorbate
Sodium nitrite
Soy lecithin
Potassium phosphate
Potassium chloride

As I reconsider the role of saturated fat in diet, given the startlingly insightful discussion by Gary Taubes of Good Calories, Bad Calories, I am reminded that not all meat is meat, not all saturated fat sources are equal.

I am concerned in particular about sodium nitrite content, a color-fixer added to cured meats that caused a stir in the 1970s when data suggesting a carcinogenic effect surfaced. The public's effort to remove sodium nitrite from the food supply was vigorously opposed by the meat council and it remains in cured meats like sausage, hot dogs, and processed meats like Cotto Salami. A 2006 meta-analysis (combined analysis of studies) of 63 studies did indeed suggest that sodium nitrite was related to increased risk of gastric cancer. This argument is plausible from animal models of cancer risk, as 40 animal models have likewise suggested the same carcinogenic association.

Also, fructose? This is most likely added for sweetness. Recall that fructose heightens appetite and raises triglycerides substantially.

I personally have a natural aversion to meat. I don't like the taste, the look, smell, and the thought of what the animal went through to make it to the supermarket. But, considered from the cold, carnivorous viewpoint of the question, "Is meat okay to eat?", among the issues to consider is whether the meat has been cured or processed, and does that process include addition of sodium nitrite.

Cotto Salami and similar products are not, of course, what carnivorous humans in the wild ate. This is a processed, modified product created from factory farm animals raised in cramped conditions and fed corn and other cheap, available foods. It is not created from free-ranging animals wandering their pastures or pens, eating diets nature intended. This results in modified fat composition, not to mention hormones and antibiotics added. These are not listed on the ingredients. Wild meat does not contain fructose or color-fixers, either.

So don't mistake "meat" in your grocery store for meat. It might look and smell the same--until you look a little closer.

Copyright 2007 William Davis, MD

Comments (7) -

  • Nancy M.

    12/18/2007 3:04:00 PM |

    Wasn't Good Calories, Bad Calories good?  Man, just what the medical world needs, a good wake-up call into how schlocky their science is (sometimes).  

    Did you finish the book yet?  Parts of it infuriated me at the stupidity and arrogance of people.  And I have to say it is getting harder and harder to have respect for medical "authorities" when you know the horrible science their training was based on, that they don't question the basis for these assumptions yet assume their patients are all idiots.

    I'd love to hear more of your comments on his book if you get a chance to blog about them.

  • MAC

    12/18/2007 3:05:00 PM |

    Would be interested in any comments you have as you "reconsider the role of saturated fat in diet" as a low carb diet appears to be beneficial in raising HDL.

    This research  from Jeff Volek was of interest: Jeff Volek, et al: Low carb diet reduces inflammation and blood saturated fat in Metabolic Syndrome.

    Also, Cordain makes the case in his FAQ for the Paleo Diet that saturated fat averaged 11% in wild animal carcasses.

  • Ross

    12/18/2007 5:50:00 PM |

    If you're going to buy something like salami, ham, bacon, sausage, or other meat product, the best source is often a deli that makes it on site.  Not only will the salami, ham, or sausage be made with fewer ingredients, but it's much tastier, fresher, and often a similar cost to mass-marketed processed meats.  

    This will not be practical for people everywhere.  Living in LA as I do, there are specialty delis all over the place and it isn't too hard to find locally made sausage, etc.  One alternative would be a deli that takes great pride in presenting the craft-made meat products of a smaller supplier.

    I've actually ignored what might be the best option of all, which is to make it yourself.  Simple ham, proscuitto, bacon, salami, many different kinds of sausage, etc. can all be made in the home with inexpensive tools and (for proscuitto and salami) a decent dry place where they won't be disturbed.  It's also fun!

    But at all costs, avoid anything made by oscar mayer or any other mass produced meat product.  It's all crap.

  • chickadeenorth

    12/20/2007 5:26:00 AM |

    Even Dr Atkins said no meats allowed that are processed or have nitrates, only meats like our ancestors ate, he said it was like "the kiss of death".I don't even considered those types of meat to have sat fats, but poision, they are all part of Franken foods to me, like Snackwell cookies.. If I have sausage I get a local German butcher to make organic elk meat into garlic sausage for us.To me low carb means nutrient dense whole foods.

  • Dr. Davis

    12/20/2007 5:36:00 AM |

    What's frightening is that, whenever I've discussed the Atkins' approach with people doing it on their own, they've virtually always included plentiful cured and processed meats.

    Somehow that part of the message didn't get stressed enough.

  • Dr. Davis

    12/20/2007 5:38:00 AM |

    In response to Nancy's first post:

    I'm embarassed to admit that Taubes was so tremendously unique and entertaining (in a nerdy sort of way) that I've savored each discussion slowly and carefully. So it's literally taken me two months to read his book. But I have enjoyed every word.

  • chickadeenorth

    12/21/2007 7:21:00 AM |

    Yes I think those of us who used the board and forum understood it better and we could call his office and talk to his nurse or leave him a question, lots misconstrued they should eat a lb  bacon a day, He said no nitrates and sat fats under 20 gr a day.I learned his big boo boo was eventually incorporating rungs adding breads, potatoes etc, they are the kiss of death IMHO.