What vitamin D form?

In response to questions regarding why don't vitamin D tablets work, here are my observations.

When I first started correcting vitamin D levels around 3 1/2 years ago, people would begin with starting 25-hydroxy vitamin D blood levels of around 20 ng/ml.

Taking, say, 6000 units vitamin D as tablets over 3 months yielded blood levels of 24-30 ng/ml. Taking 6000 units in an oil-based form, and blood levels would commonly be 60-70 ng/ml.

In other words, tablets are very poorly absorbed. I also saw very erratic absorption with tablets, with tremendous variation in blood levels.

I witnessed this effect many times. I finally began telling patients to avoid the tablets altogether. It's simply not worth it. Taking dose X of tablets, you cannot predict what the blood level of vitamin D will be.

Now, you can sometimes make the tablets get absorbed by either taking with a teaspoon of oil (e.g., olive, flaxseed) or taking with an oil-rich meal. However, I am uncertain just how consistent the absorption is under these circumstances, not having done this enough times to know.

Oil-filled gelcaps are no more expensive than tablets (or perhaps a dollar more). Health food store employees and pharmacists don't know this. I have had many patients come to the office claiming they changed to tablets because that's all their health food store or pharmacy carried and the person behind the counter assured them it was the same. Blood level of vitamin D to confirm: right back down to the starting level or near it--little or no absorption.

The only way to know whether a preparation is absorbed is to check a blood level. But, in my experience, having checked vitamin D blood levels thousands of times, gelcaps never fail; tablets fail over 80% of the time.

Comments (36) -

  • TedHutchinson

    2/16/2009 9:13:00 AM |

    Effective strength D3 is not available over the counter in the UK. UK readers have to buy from the USA.
    Iherb do Now foods 5000iu D3 in olive oil capsules very cheap.
    Orders £18 or over are not only subject to Customs duty but our Post Office charges £8 extra to collect the tax.
    Using Iherb $5 discount code such as WAB666 reduces the price of 360 to under the tax threshold. Leaving the daily cost including P&P to 5.25p daily

  • TedHutchinson

    2/16/2009 12:01:00 PM |

    May I also draw readers attention to this half hour video from Cedric Garland about Vitamin D status and cancer incidence and progression.
    You will note Garland suggests 60ng 150nmol/l for lowest cancer incidence.

  • fritz

    2/16/2009 1:48:00 PM |

    Is the vitamin D from cod liver oil effective?

  • Anonymous

    2/16/2009 2:10:00 PM |

    Slightly off topic, but I just read that congress is going to vote on a bill to cut medicare coverage of vitamin D levels, so now we will have to rely on private insurance, or simply pay ourselves.

    Jeanne shepard

    By the way, I prefer not to be "anonymous" but the Google Blogger doesn't remember my password, and won't let me select a new one.

  • Anne

    2/17/2009 3:28:00 AM |

    Some of the vitamin D experts warn against using cod liver oil. http://www.vitamindcouncil.org/newsletter/2008-december.shtml

    One concern is too much vitamin A if you took enough of the cod liver oil to get the D you need. Another is that vitamin A and D compete with each other.

  • TedHutchinson

    2/17/2009 10:18:00 AM |

    Read what Dr Cannell says about Cod liver oil here

    A typical 5ml tsp of CLO contains roughly 400iu. Most people require on average 5000iu/daily so the amount from CLO is insufficient.

    Twice yearly $30, 25(OH)D blood spot tests, available by post from this source

  • Rick

    2/17/2009 10:49:00 AM |

    iHerb.com also has Country Life Vitamin D3 2500 IU (200 softgels).

    Thanks for answering the questions about tablets so quickly, by the way.

  • Tom

    2/17/2009 11:38:00 AM |

    For the benefit of UK readers, I'd like to second TedHutchinson's informative comment. I use the same product from the same supplier Smile

    It's worth noting that postage and packing cost from the US does not contribute to the value of the order for the purposes of taxes and extortionate 'fees'.

  • Matthew

    2/17/2009 1:08:00 PM |

    I don't understand why taking a vitamin D3 capsule will not raise level of 25(OH)D when consuming it with fat or meal containing fat. Should get the same results...

  • Anonymous

    2/17/2009 5:43:00 PM |

    First, let me say that I really love your blog.  I learn so much every time I come here.

    I do have a question for you.  What do you make of this site:


    On the surface, she appears to be a competent scientist, but she blames everything (and I do mean everything from macular degeneration to brain lesions) on too much Vitamin D and claims that the road to universal health should begin with driving one's Vitaman D levels to below 20 ng/mL.  A friend of mine just sent this to me in a panic.  Please let us know what you think.

    Thanks so much!

  • Steve L.

    2/17/2009 7:39:00 PM |

    The Costco effect.  I had been wondering why so many people use the tablet form.  Just noticed yesterday that tablet is the form of Vitamin D that Costco carries.

  • Diana Hsieh

    2/17/2009 8:54:00 PM |

    All of the vitamin D capsules that I checked in Whole Foods yesterday were composed of some kind of frankenfood oil in them, most notably soybean oil.  Can anyone recommend any brands that use something better?  

    (I have the same problem with my vitamin E complex, but I'm not convinced that I should be taking that anyway -- although it does seem to help the inevitable dry skin in winter here in Colorado.)

    BTW, my husband and I got our levels tested thanks to your recommendations.  Mine were excellent (probably thanks to many months of good supplementation), but his need some work (despite some more moderate supplementation).  Thanks for the info!

  • David

    2/18/2009 4:37:00 AM |

    Re: the http://bacteriality.com/2007/09/15/vitamind article...


    Dr. Davis wrote about this issue (more or less) last year: http://heartscanblog.blogspot.com/2008/03/marshall-protocol-and-other-fairy-tales.html


  • Michael

    2/18/2009 5:55:00 AM |

    @ Diana Hsieh
    Don't know if this is available where you are (I'm in Australia) but I use this brand of D3 for this very reason. It's in fish oil, of reasonable potency.

    THOMPSON'S Vitamin D (1000mg) with Fish Oil (500mg) - 60 gelatin-free caps


    Product made in New Zealand. Hope this helps.

  • Anna

    2/18/2009 6:40:00 AM |


    Our family likes Carlson Vit D products.  They are definitely absorbable, because the whole family went from the low end fo the reference range to around 70-86 ng/ml in the past few months).

    Mostly we use Solar D Gems in the 2000 or 4000iU capsules.  There is a bit of Norwegian CLO & EPA?DHA in them, and lemon flavor.  They chew up easily, too, but can also be swallowed.

    The non-chewable capsules are much tinier and are made with sunflower oil, but even that is a very tiny amount in this very small capsule.

    The Carlson D drops in the 2000iU/drop dose is made with coconut oil (though it is fractionated, to keep it liquid).  But it's only a drop.

    I find very good prices at www.vitaminshoppe,com, usually for about 2-4 ¢ per each 1000iU (that's how I make price comparisons).  Plus Vitamin Shoppe has a frequent buyer program so purchases earn points toward fairly generous coupons (such as $5 off a $15+ purchase), and shipping is reasonable (sometimes free).  

    Or I buy Carlson Vit D3 at the local store when they are on sale (stores that sell a lot of Carlson product often pass along "mfg discounts" or "special buys").

  • TedHutchinson

    2/18/2009 11:09:00 AM |

    Mark London  MRL@PSFC.MIT.EDU has provided a detailed scientific rebuttal of the Marshall Protocol here
    Is the MP Treatment for Sarcoidosis Helpful for Other Chronic Diseases?

    MP’s Vitamin D Theories Are Not Supported by Lab Studies.
    Updated July 2, 2008

    Dr Davis has previously addressed this issue in the blog entitled
    The Marshall Protocol and other fairy tales

    Diana Hsieh
    The capsules I suggested are dissolved in olive oil.
    Carlson 2000iu sunflower oil $12.22
    Carlson also do Solar Gems in Cod liver oil.

  • Anonymous

    2/18/2009 1:35:00 PM |

    Diana Hsieh,

    I believe the NOW foods brand D3 formulations are suspended in olive oil.

    Carlson's Vitamin D3, 2,000 IU is suspended in sunflower oil.

    That being said, most of these D3 capsules are quite tiny, so I am not sure that they contain a huge amount of oil, unless you are taking more than 10,000 IU's daily (i.e., 5 capsules).

    As to sources, iHerb is the best and most user friendly, and I won't even give you my $5. discount code, as previous poster did.  You can sign up for your own discount number at the iHerb website.

    Hope that helps!

  • Sam

    2/18/2009 3:30:00 PM |


    I'm currently using Carlson 2000IU gelcaps which contain sunflower oil (omega-6, even if small quantities) and a few other more benign ingredients.

    When these are exhausted I'm switching to Carlson D-drops in which D3 is dissolved into medium chain triglycerides (MCT).

  • Anonymous

    2/18/2009 4:50:00 PM |

    Thanks everyone for the input.  I feel much better now and am off to take my gel-capped Vitamin D3.

    All my best,

  • TedHutchinson

    2/18/2009 9:21:00 PM |

    When researching Carlson Solar Gems earlier I mentioned they contain Cod liver oil but no Vitamin A Content is listed on the Carlson's website.
    So I emailed Carlson's to confirm the vitamin a content. They replied
    total Vitamin A is below 2% of the daily value which is the threshold above which the FDA requires you to list the Vitamin A content.
    As adult RDA for vitamin A is 700~900iu, below 2% of that is below 14~18iu. So there is really is no reason to avoid Solar Gems because of their potential Vitamin A content.

  • Anonymous

    2/19/2009 12:52:00 AM |

    Dr. Davis,

    Appreciate your elaborating the tablets vs. capsules point and thank you for continuing to take the time to write such informative posts!

  • Anonymous

    2/19/2009 7:46:00 PM |

    "Heart disease was once thought to be less of a problem for women than for men. Research now indicates that heart disease is the No. 1 cause of death among women in the US, while confirming that women with an intact uterus have a lower incidence of heart disease because they benefit from the uterine advantage." Visit http://www.truthout.org/021609R for the full article.

  • Anonymous

    2/20/2009 12:01:00 PM |

    Dr. Davis,
    Are gelcaps with dried powdered form of vitamin d3 as effective as oil filled gelcaps?

  • Ricardo

    3/26/2009 12:58:00 AM |

    Dr. Davis, "Americans Low on Vitamin D" - http://www.webmd.com/news/20090325/americans-low-on-vitamin-d

  • Anonymous

    4/22/2009 6:37:00 PM |

    I've had great results from powdered gelcap from D-Max (5000 IU) from Nature's health Supply, but a bit less from NOW olive oil gelcaps (5000 IU). Just a hunch, because I have an autoimmune disease and I'm trying to work out my symptoms. So no 25(OH)D test here.

    I'll try those Carlson's next.

    Great blog by the way!

  • Anna

    4/22/2009 8:49:00 PM |

    I just ordered some D3 to send to my 81 yo MIL and 46 yo SIL in London.  I'm quite sure they are going to very deficient (they just ordered the www.grassrootshealth.net home testing kit as it's a pain to get NHS to agree to test).  

    I found Bio-Tech D3-5 (5000iU cholecalciferol capsules  - powder in a tiny gelatin capsule) offered on Drs. Eades's Protein Power website at a great price, 100 qty for $8.  Shipping via UPS was $6.45 to my location for up to 10 bottles.  That makes the price per 1000iu incredibly low.  I bought a year's supply (8 bottles) to mail to my in-laws, plus two bottles for me.  Note I was very surprised at the small size of the box, but it did contain the 10 bottles I ordered, but the capsules and bottles are small and light, which is nice when ordering so much at once and mailing it again.  Fast delivery, even with UPS ground service.

    I just had another 25 (OH)D test drawn last week; I'll get the results tomorrow at my endo appt for my thyroid.  I was averaging 5000iU/day  supplementation with various Carlson D3 products, based on previous 25 (OH)D test results and supplementation levels.  So I'll switch to the Eades' Bio-Tech formula now and see how my 25 (OH)D is in late summer/early fall.

  • David

    4/22/2009 9:40:00 PM |


    I'd be very interested to hear a follow up from you when you retest after being on the Bio-Tech D3 for awhile. I'm of the mind that D3 in softgel form is more absorbable and hence more efficacious for raising and maintaining 25(OH)D levels, but I see many of the "big guns" (e.g. Cannell, Eades, etc.)promoting/selling the powdered Bio-Tech formula. Perhaps you could report back here with your results?


  • Anna

    4/23/2009 6:27:00 PM |

    Sure.  I'll be retesting  thru my endo in 6 mo.  But I might do a mail-in test via www.grassrootshealth.net before that.  

    I'm guessing a gelatin capsule filled with a powder (might be an oily powder,too) is more absorbable than a hard tablet form.

    Btw, I just got my lab result for 25(oh)d---a nice 68ng/mL (after months of 5000iU D3 carlson oil gelcaps and/or oil drops .  Also was an easier winter than i've had in years, which I think might be due to more sunlight and Vit D.

  • David

    4/23/2009 7:59:00 PM |

    Thanks, Anna. 68 ng/ml-- Good for you! You know, all my life, I've had tough winters. I would always get very sluggish and depressed. I mean I would get really, really down. But ever since I've started the vitamin D, the winter blues are a thing of the past. This alone is probably the most noticeable effect I've ever had from taking any supplement. It's a very dramatic and welcomed change.

  • Herry

    5/27/2009 9:41:31 AM |

    I will read from time to time for that.


  • Anonymous

    8/26/2009 6:34:03 PM |

    That means D3 in Calcium tablets like Citrical is probably poorly absorbed  too, am I correct?

  • David

    8/27/2009 10:27:06 PM |


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    12/13/2009 2:00:04 AM |

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  • Anonymous

    5/4/2010 2:15:47 AM |

    GNC has Vit D drops.....do you feel this is good?

  • buy jeans

    11/3/2010 12:30:44 PM |

    Oil-filled gelcaps are no more expensive than tablets (or perhaps a dollar more). Health food store employees and pharmacists don't know this. I have had many patients come to the office claiming they changed to tablets because that's all their health food store or pharmacy carried and the person behind the counter assured them it was the same. Blood level of vitamin D to confirm: right back down to the starting level or near it--little or no absorption.