Vitamin D Testing

Well so now I have an enigma on my hands. Some weeks back you may recall that I blogged about the great Vitamin D Project by Grassrootshealth. That was Feb 27th and within a few days I had my test kit, punctured my finger, blotted blood, and sent it off.

Roughly two weeks later, a couple of days ago, I had blood drawn for my various series of tests and one I requested was a vitamin D test (25-hydroxy vitamin D). Coincidentally, I got both results today, one from blood taken two weeks ago and one from a current sample.

2 weeks ago: 120 ng/mL

Current: 85 ng/mL

That's quite a difference (the magnitude being greater than the average total vitamin D level for most people). One possibility is lab error, of course. Another is that the first test was at only a week back from spending hours per day in the Puerto Vallarta sun (I continued my 6k IU per day). But it's hard to imagine it could dissipate so rapidly in such a short time, so is something fishy somewhere?

I'm hoping it's the latter one that's fine, as 85 is exactly where I want to be; as well it must be noted that it was an actual blood draw; whereas, the former was a drop on blotter paper. I have no idea of the comparative difference in terms of test quality.

Anyone have any ideas?

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  1. Anna on March 19, 2009 at 20:34

    I agree with Monica, I think you were elevated on the first test from the vacation sun exposure, plus the 6K of supplemental D is on the high side (not if you aren't getting sun, though). In the winter, you probably burn through D pretty fast, too.

    My husband's level went up pretty fast 46 in early January after taking 4000 iU for several months, plus a lot extra in December to avoid the colds spreading around us, Then he upped his dose to 8000iU daily and had a test result of 90 at the end of January. My result was 122, but I was taking a lot in December and January. I dropped back to 5,000iU, which I estimate will keep me in the 80-ish zone when I test again in April. In our family, for kids and adults alike, 1000iU per each 25 pounds looks like a good fall-spring dose. Tests were too low on less and a bit too high on more.

    Lately role of the skin oils (sebum) accumulating or being washed off before absorption of the Vitamin D has been popping up here and there, but with few details, and that has me wondering. Skin oils diminish with age as well as skin thickness.

    Last spring and summer I tried to get more a bit more measured sun exposrue (at home in coastal So Cal and on vacation in July in Italy) instead of taking supplements – and my level went down from 44 in Dec '07 (taking 2000iU for about 8 mos) to 40 in late August from just what I made from sun and whatever was in my food. I'm 47yo, so probably already on the downside of the Vit D production slope. I don't tan very well at all and I lose what tan I get quite fast, too.

  2. nonegiven on March 19, 2009 at 21:51

    I was reading one of the newsletters from Cannell a while back He said there were a couple of different tests and one of them was extremely dependent on the experience of the lab personnel. He said the test one of the major labs was using was regularly coming back much, much higher than another major lab. Which labs ran the two different tests?

  3. Methuselah - Pay Now Live Later on March 19, 2009 at 23:21

    Richard – no ideas, but I am awaiting my test kit from the same organisation and am very interested to see what my own results are after a UK winter of zero sun exposure, but a serious sardine and egg habit!

  4. Monica on March 19, 2009 at 16:35

    Hi Richard. That's pretty interesting. There could certainly be a difference in the two tests. I don't know enough to comment on that.

    However, I don't think it's outside the realm of possibility that your later test reflects a week out of the sun. According to the Vitamin D Council website, you can make 7500 IU just by sitting in the sun for 10 minutes. I think people get a whopping dose of vitamin D when they sit in the sun. I imagine your levels might have been very high when you were in Mexico.

    This raises the question of how the body processes and excretes vitamin D. I honestly don't know the answer to that question but hopefully one of your other readers can shed some light on the matter.

    I'm really looking forward to getting my results in the mail! However, I took a whopping 50,000IU dose when coming down with my second cold this winter. The D knocked it flat, but the old test is not really going to be indicative of what my current levels are, just whether I was deficient at that time….

    Of course, this does raise the question of whether we really understand what are truly healthy levels of vitamin D and how the body processes it.

  5. Richard Nikoley on March 19, 2009 at 16:46

    But then there's the issue of Dr. Davis' claim that we begin losing most ability to synthesize D from the sun at age 40 and onward. I'm 48. I have not looked into his claim at all, but I think I'm motivated to do so now.

  6. Monica on March 19, 2009 at 17:01

    Yes, it certainly would be good to know more!

  7. Tom Moertel on March 20, 2009 at 08:44


    Take a look at the slides from Robert P. Heaney's presentation at Grass Roots Health's conference last April. They contain a wealth information about the relationship between D3 and 25(OH)D over time. You can find a copy of the slides here:

    Cheers! –Tom

    P.S. If you're no longer at the cabin, would you mind checking on that brand of curry paste you use?

  8. Pauline on March 20, 2009 at 03:16

    I went to Portugal for a week and didn't take any Vit D3 when I was there. Temps were around 16-19 degrees but I am always careful of too much sun exposure as I am fair skinned. When I got back to the UK I met up with a friend who had flu and I came down with the beginnings of it very quickly. I immediately started taking 2500 – 3000 iu Vit D3 and 2000mg Vit C every day and it kept the flu symptoms under control and I was over it in about a week. My partner and I have been taking vit D3 regularly since then and I notice my skin is softer than it normally is and my nails are growing faster (cut them more often). 2007 and 2008 were the only two years in which I did not take a holiday to South Africa and get my monthly dose of sunshine and I have felt the effect of the SAD – not enough sunshine and too many grey weather days. I feel that the Vit D3 is definitely helping with that too. My partner has noted similar effects and he is using the Vit D3 from the capsule directly on a patch of skin on his legs that periodically flares up (may be psoriasis). I am thrilled to be learning about Vit D3 as my ancestors came from the north in Scotland and I have been reading how there is a definite link to Vit D3, the northern hemispheres and many illnesses. Keep up the fantastic work Richard, we are all benefitting with you. Thank you.

  9. Jake on March 20, 2009 at 04:29

    If you got the blood test from Quest, their results are running 1/3 higher than standard. If you did, that would make both tests equal.

  10. Peter on March 19, 2009 at 23:41

    There has been recent controversy regarding lab testing accuracy. Not sure if this pertinent to your tests.

  11. SimpleMan on March 20, 2009 at 11:29

    Does anyone know which lab uses for their 25(OH)D?

  12. SimpleMan on March 20, 2009 at 12:50

    Just got an email back from and they said LabCorp does their 25(OH)D.

  13. Monica on March 20, 2009 at 07:38

    DAction's test is from ZRT labs, the same place that the vitamin D council recommends.

  14. Richard Nikoley on March 20, 2009 at 07:50

    Thanks Anna. Great info and experience. That gives me more confidence that it was massive sun exposure. I was in swim trunks only and fully exposed to the sun from about 10a – 2p every day.

  15. Richard Nikoley on March 20, 2009 at 07:52

    For the first, it's whoever Grassrootshealth is using. The second is Kaiser Permanente, an enormous HMO.

  16. Pauline on March 24, 2009 at 03:38

    Hi Richard, I wonder if there is a simple graph which would help with working out what Vit D3 level would suit each person – my partner and I are still trying to work that out. It depends on your height, weight, age, exposure to sunlight and where you live and work. Some comments by women indicate 5000 iu and then I wonder what are their ages, weight, height – would be interesting to be able to have a graph that is understandable to the layperson (the scientific graphs are hard to interpret). For instance we know the level that you take but what is the amount that your wife takes. At the moment a safe level for me seems around 3000iu of vit D3 because I feel intuitively safe there. But that might just get it to the minimum level for me, just not sure. Any ideas?

  17. Richard Nikoley on March 24, 2009 at 10:27


    Yes, I've looked through all those slides (various presentations at that site). If you check the archives for December 30 or 31st, I actually did three posts to highlight and summarize three of those presentations.

    As to curry paste, I had been using Thai Kitchen, but have since been going to an Asian market and getting various imports that have nothing but the spices in them.

  18. Richard Nikoley on March 24, 2009 at 11:28


    Don't have time to check now but will make a todo. In the meantime, you might check the websites of vitamin d council, grassrootshealth, and dr mercola.

  19. Monica on March 24, 2009 at 14:02

    Pauline I think that the only way to know is to get your levels tested and then assume a 1 ng/mL rise to the point where you want to be for every 100IU intake. For instance, if you come back at 20 ng/mL and want to get up to 80, you should take 6000 IU daily.

  20. Richard Nikoley on March 24, 2009 at 14:35

    And then how about sustaining it?

    Richard Nikoley

  21. Pauline on March 25, 2009 at 03:08

    Thanks for that, I think I was asking on behalf of anyone who wants to go on Vit D3 say for 3 – 6 months before testing and trying to start out on a dose of Vit d3 daily. I think that could be anywhere between 3000 – 6000 IU daily and guessing the probabilities of level of deficiency from say age, height, weight, where you live etc – available sun exposure for the season of the year. On Art De Vany's sight the video link to a doctor who gave a special lecture on Vit D3 said he took 1000 iu three times a day to get his level around 70-80 ng/ml so that seemed a safe place to start. Thanks for your input and I will keep investigating.

  22. Monica on March 25, 2009 at 06:57

    I'm not really sure. If you look at the slides linked above, it looks like after 3 months you pretty much reach your desired level and a month more after supplementing with the same level you basically level off and don't keep increasing. I suspect that continued supplementation with the same level isn't really going to hurt — though it may not be necessary.

  23. Monica on March 27, 2009 at 17:38

    HI Pauline, if you're still checking. here's my vitamin D story. You should check it out.

  24. Debbie on April 1, 2009 at 13:02

    Hi, well my test came back from Daction at a 46 – that's after 8 weeks of supplementing at about 5000 IU daily. I get virtually zero sunlight during the day since I work in a windowless cubicle. I'm still trying to wrap my head around this article though:

  25. Debbie on April 1, 2009 at 18:00

    Yeah, Dr. Davis says on his blog that no one takes Marshall seriously. Guess I won't either. But it can get hard for the average layperson as they toss around study after study that apparently backs up their claims. The head starts to spin after a while! No wonder so many people are anti saturated fat/paleo type eating! I'm sure their are websites and blogs that sound just as plausible that "prove" how awful it is for your health.

  26. Richard Nikoley on April 1, 2009 at 13:38

    I'd heard something about this, somewhere. Got to dig into it. At first glance it's ludicrous and evolutionarily contradictory.

    Ah… Just got an email reply from Stephan, which I'm sure he won't mind me posting:

    "Those are the Marshall Protocol people. They don't believe vitamin D deficiency causes rickets. They say vitamin D is immunosuppressive… if that's the case, I suppose humans evolved to have suppressed immune systems… thank goodness we finally figured out how to live indoors so we could avoid vitamin D! It's pseudo-science. They believe chronic disease is caused by tiny intracellular bacteria that you can eradicate using vitamin D restriction and low-dose antibiotics. There may be some truth to the idea that infection causes or contributes to some chronic diseases, but these people are just abusing science…"

  27. StephenB on April 9, 2009 at 08:15

    I just got my GrassrootsHealth results back. The results seem to be reasonable. Here's some history for my D levels:

    Date…..Vitamin D3 (IU)….Blood Level (ng/ml)

    The first two measurements were taken through LEF. I'll get another test this May when LEF does their annual blood test sale so that will give me a comparison number.


  28. Mike on April 25, 2009 at 05:18

    Here is another site that tells you all about vitamin D and the conditions that it may prevent. They also have a good newsletter that is worth signing up for

  29. Mike on April 25, 2009 at 05:19

    Forgot to actually mention the site! it is

  30. Richard Nikoley on April 25, 2009 at 09:24

    Thanks, Mike. I'll have to take a look at that.

  31. Dave on May 23, 2009 at 15:28

    Just read what I wrote…just wanted to clarify…I thought the other post was ancient (not the info) so I didn't think you (or anyone else) would see the comment. So far, that's the best deal I've found for vit D…

  32. Dave on May 23, 2009 at 15:22

    This might be a little off topic, but the other post where you talk about sources for vit D and K2 is ancient (in terms of the Internet)..anyway, I've been spending a lot of time here the past day or so and wanted to know if you had ever come across vitamin D in liquid emulsion form. Seems like it would be the most absorb-able. I just picked up a bottle at (http://www(dot)lef(dot)org/Vitamins-Supplements/Item00864/Liquid-Emulsified-Vitamin-D3.html) and according to the specs, that 1 oz bottle provides 2,000 IUs per drop for about $30 if you are not an lef member, and there are 975 drops in the bottle. Good deal if you ask me.

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