If you’re following the health news, you know that vitamin D currently is in the media spotlight, and rightly so. Will Brink just did a great podcast “Vitamin D3 – scam or panacea?“, giving an overview on the importance vitamin D. In this article I will expand upon some key points taken up in the podcast, and back up the case with a solid reference list of recent studies on the topic. I will also present some revealing prevalence stats on vitamin D insufficiency, in order to convince you to get your blood levels checked to find out your vitamin D status.

Vitamin D is interesting for several reasons:
1. The role of vitamin D for health promotion has undergone a paradigm shift. While traditionally thought to only be important for development and maintenance of strong bones, an impressive body of scientific research has accumulated over the past decade, showing that adequate vitamin D levels are necessary to prevent many diseases, especially cardiovascular disease, high blood pressure, endothelial dysfunction, diabetes (both type-1 and type-2), the metabolic syndrome, chronic inflammation, cancer, osteoporosis (including falls and fractures), muscle weakness, cognitive dysfunction and mental illness, autoimmune diseases (e.g. multiple sclerosis, rheumatoid arthritis), infectious diseases, as well as infertility and adverse pregnancy and birth outcomes [1-24].
Vitamin D deficiency/insufficiency is associated with all-cause mortality [1], and supplementation has been shown to decrease mortality rates [25, 26]. It has been estimated that doubling vitamin D levels in the general population (from 21 ng/mL to 44 ng/mL) would reduce  vitamin D-related disease mortality rate by 20%, and increase life expectancy with about 2 years [27].
2. Insufficient levels of vitamin D also have direct implications for fitness enthusiasts and athletic performance, due to the importance of vitamin D for muscle function (I will cover this in much more dept in an upcoming article) [28-39].
3. In contrast to other vitamins, vitamin D deficiency/insufficiency is very common (more on that below).
4. The vitamin D requirement for health promotion and protection against the mentioned diseases and muscle dysfunction is much higher than the dietary recommendations (RDA) for bone health [4, 40-45].
Having heard about all the vitamin D benefits you might wonder what is the optimal vitamin D level? How low is too low and how high is too high?  How much vitamin D does one have to consume to reap all the benefits? Let’s find out…

What are the blood level thresholds indicating vitamin D insufficiency?
The form of vitamin D that is measured in blood and used to indicate vitamin D status is called 25-hydroxy-vitamin D (abbreviated 25[OH]D) [9, 46]. So when I talk about blood vitamin D levels in this article, it is 25-hydroxy-vitamin D I am referring to (it’s easier for most people to think in terms of vitamin D levels than 25[OH]D or 25-hydroxy-vitamin D).
There is no official consensus about what is the optimal vitamin D level, and it is possible that different endpoints require different optimal vitamin D levels. However, based on the currently available data, prominent vitamin D researchers and authorities have presented the following guidelines:
Vitamin D status thresholds as defined by blood 25-hydroxy-vitamin D (25[OH]D) levels.

ng/mL nmol/L   Vitamin D status   Reference
below 20
over 30
over 150   
Ideal level
Risk for toxicity 
[18, 22, 41, 47, 48, 50-58]
[4, 9, 22, 28]
[9, 46, 59]

* Severe deficiency that causes softening of the bones occurs with levels below 10 ng/mL (25 nmol/L) [60].
* Blood (serum) levels of 25(OH)D are reported in either  nanograms per milliliter (ng/mL) and nanomoles per liter (nmol/L).
* 1 ng/mL = 2.5 nmol/L
Traditionally, government issued health guidelines have stated that vitamin D levels of 20 ng/mL are sufficient. However, in light of new data prominent vitamin D researchers now recommend vitamin D levels in the range of 50-60 ng/ml, for both health promotion and athletic/physical performance [4, 9, 28]. As indicated in the table, even though this new recommended level is 2-3 times the old recommendation, it is far below the risk for intoxication and is thus a safe target to aim for in order to achieve all the vitamin D related health benefits (which is will cover in dept in upcoming articles).
How common is vitamin D insufficiency?
Low vitamin D status, i.e. vitamin D deficiency or insufficiency, is far more common than previously thought.
When looking at stats, it’s important to distinguish vitamin D deficiency from insufficiency. While severe vitamin D deficiency isn’t as prevalent, vitamin D insufficiency is:
* 36% of the US population is deficient, with vitamin D levels below 20 ng/ml [61].
* In a study on subjects characteristic of the US white population, it was found that only 18% have a vitamin D level over 30 ng/ml [62]. Thus, a whopping 82% are insufficient in vitamin D!
Similar results were found in the 2004 National Health and Nutrition Examination Survey (NHANES) [63] and in other analyses [58].
* To make things worse, data from (NHANES) showed that the number of persons with a vitamin D level below 30 ng/mL nearly doubled between the 1994 and 2004 [63].
Bearing in mind that the desired range as recommended by vitamin D research experts, is 50-60 ng/ml, these stats are alarming and underscore the fact that vitamin D insufficiency exists in epidemic proportions in the US. This vitamin D insufficiency epidemic spans across the globe [61].
How should I get my vitamin D?
The sources of vitamin D are sunlight exposure, food and supplements [9]. However, only a few foods are naturally rich in vitamin D [9]:

Salmon, fresh wild caughtSalmon, fresh farmedSalmon, cannedSardines, canned Mackerel, canned Tuna, canned Egg yolk Fortified milk 600–1,000 IU/3.5 oz vitamin D3100–250 IU/3.5 oz vitamin D3300–600 IU/3.5 oz vitamin D3300 IU/3.5 oz vitamin D3 250 IU/3.5 oz vitamin D3 236 IU/3.5 oz vitamin D3 20 IU/yolk vitamin D3 or D2100 IU/8 oz, usually vitamin D3

Thus, unless you eat oily fish every day (which would carry risk for toxicity from environmental contaminants), you cannot rely on your diet to cover your vitamin D needs.
Another source, the safety of which is controversial, is sunlight exposure. This is why vitamin D is called the “sunshine vitamin”. Because vitamin D can be produced by the skin upon sun exposure, it is actually not a vitamin in the traditional sense (per definition, vitamins are essential because they cannot be produced by the body). In fact, vitamin D is a pre-hormone to the hormone calcitriol (which is the active hormonal from of vitamin D that exerts effects on different tissues in the body). However, as said above, it is the vitamin D metabolite 25-hydroxy-vitamin D (25[OH]D) that is used to indicate vitamin D status and to guide supplementation needs.
Even though sun exposure theoretically is an effective vitamin D source, it cannot safely be relied on. A recent study showed that vitamin D supplementation is actually more effective than advised sunlight exposure for treating vitamin D deficiency [64]. The inferiority of sunlight exposure to improve and keep optimal vitamin D status is supported by findings of prevalent vitamin D insufficiency even in sunny Florida [65]. This was also underlined in a study of tanned prototypic “surfer dudes” (mean age 24 years) who overall reported an average of 22.4 hours per week of unprotected sun exposure [66]. Despite this abundant sunshine exposure, the mean blood vitamin D level was only 31 ng/mL (79 nmol/L), and 51% had a level below the recommended ideal 30 ng/mL (75 nmol/L) cutoff for sufficiency [66].
Also, the capacity to produce vitamin D in the skin is lower in dark skinned people, and diminishes as we get older [67, 68]. The darker skin types (III–VI) and the oldest people (>59 yr) are at the highest risk for not making enough vitamin D3 during the year from everyday outdoor exposures, even with a 2–3 week summer vacation [68]. People living in northern latitudes are especially at risk of not getting enough vitamin D producing UVB radiation from the sun [68, 69].
Another issue with sun bathing is the consequence of skin aging and risk of skin cancer. Unfortunately, the UVB radiation that produces vitamin D in the skin, is also the culprit causing skin cancer and wrinkling [70, 71]. This is a legitimate reason to not attempt to cover your vitamin D requirements by sun exposure. And even if sun exposure was a safe and reliable way to cover vitamin D needs, in today’s society with hectic work schedules most people don’t have much time to be out in the sun. It has been established that most adult Americans do not go outside enough to meet their minimum vitamin D3 needs all year [68].
Vitamin D supplements come as either vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol) [4, 72] and in over-the-counter dosages of up to 10,000 IU. In the past there was a scientific “D-bate” over the efficiency of D2 vs. D3. However, a recent systematic review and meta-analysis of all studies published to date concluded that vitamin D3 is more effective at raising blood levels of vitamin D (i.e. 25-hydroxy-vitamin D) [73]. More specifically, vitamin D3 is approximately 87% more potent in raising and maintaining 25-hydroxy-vitamin D levels, and produces 2- to 3-fold greater body storage of vitamin D than does vitamin D2 [74]. Given its greater potency and lower cost, the vitamin D3 form should be the preferred supplement choice to elevate and maintain health promoting vitamin D levels.
Bottom Line
Now you know the importance of finding out your vitamin D level. Either ask your doctor to check it, or order a vitamin D blood test online without a doctor’s prescription if you don’t have health insurance. Life Extension offer great blood testing services, including vitamin D testing. Get your 25-Hydroxy-vitamin D Blood Test now!
If your blood level of 25-hydroxy-vitamin D shows that you are insufficient in vitamin D (which most folks are), you will need to get a vitamin D3 supplement to reap all the health and performance benefits from this multi-functional pre-hormone. Vitamin D supplementation is the fail-proof way to go in order to safely and effectively get your vitamin D level to the optimal 50-60 ng/mL range. Adequate vitamin D supplementation and sensible sunlight exposure to reach optimal vitamin D status are among the front line factors of prophylaxis for a spectrum of commons diseases.
In the next article I will explain that there is no clear cut vitamin D dose-response relationship because of the considerable variation in how individuals respond to vitamin D supplementation. The response to treatment varies with baseline vitamin D levels, body fatness, differences in activities of vitamin D metabolizing enzymes, skin pigmentation (race), season and geographic location (latitude). This is why it is so important that you check your baseline level and also keep monitoring it regularly, e.g. every 6 months, to see how you respond to vitamin D3 supplementation. In the next article I will cover supplemental vitamin D “loading” and maintenance dosages to raise your level fast and keep it there. I will also present studies that have reported mega-dosages of vitamin D intake, to give you a perspective, and cover safety and toxicological aspects. Stay tuned!
About Monica Mollica – www.Trainergize.com

Trainergize.com is an unbiased informational and motivational resource, presenting the latest health, performance and anti-aging related research findings to the public, in an easy to understand way.
While still under development, trainergize.com is committed to providing credible, objective, and reliable health information on a wide range of topics that impact your health and wellness and that of your family. The information is derived from scientific research studies published in top tier medical journals and/or presented at professional medical meetings.
Trainergize was founded and is maintained by Monica Mollica, who has a Bachelor and Master degree in Nutrition from the University of Stockholm / Karolinska Institue, Sweden, and has studied at renowned Baylor University, TX. Today Monica works as diet/health counselor, medical writer, health journalist, and website developer. She is also a fitness model.
As a young athlete, Monica realized the importance of nutrition for maximal performance at an early age, and went for a major in Nutrition at the University of Stockholm. During her years at the University she was a regular contributor to the Swedish fitness and bodybuilding magazine BODY, and she has written a book (in Swedish) “Functional Foods for Health and Energy Balance”, and authored several book chapters in Swedish publications.
After having earned her Bachelor and Master degree in Nutrition, she completed one semester at the PhD-program “Exercise, Nutrition and Preventive Health” at Baylor University Texas, Department of Health Human Performance and Recreation.
Having lost her father in a lifestyle induced heart attack at an age of 49, she is specializing in cardiovascular health, and primary/primordial prevention. She is a strong advocate of early intervention in adolescence and young adulthood, and the importance of lifestyle habits for health promotion at all ages.
Today, Monica is sharing her solid academic knowledge, real-life experience and passion by offering diet/nutrition/exercise/health consultation and coaching services, and working as a health journalist and medical writer on topics related to fitness, health promotion and anti-aging.
She is currently in the process of writing a book “Anti-Aging – it’s your choice”, and developing the related website www.SuccessfulAging.me
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  1. Martin Havelka 6 years ago

    I recently had a few blood tests done (Testosterone, Cholesterol, CRP, etc, inspired by the “it’s in your blood” article), and everything was normal or even quite favorable, however my Vitamin D came out at a shockingly low 6.6 ng/ml!! I guess I’m a prime example of how widespread this deficiency is, even in otherwise healthy people.
    Better start popping them pills!

    • Monica 6 years ago

      Indeed you are!
      Being so severely vitamin D deficient i’d recommend you very large dosing dose. Is you doctor willing to prescribe you vitamin D treatment? If not, I’d recommend 50,000 IU per day for 10 days, and then 12,000 IU per day for 20 days. After that, get your vitamin D level checked and adjust the dose based on your new reading.
      I will cover the issue of vitamin D dose-response and strategies to treat vitamin D deficiency in my next article. Let us know how you respond and how treatment of your vitamin D deficiency makes you feel. Being so deficient I can tell you are going to notice a major strength improvement in the gym. Keep us posted 🙂

      • Martin Havelka 6 years ago

        Thanks for your answer! FYI, I am from Austria, and living in Germany right now. Doctors here aren’t exactly forward-thinking (most in the US probably aren’t either, but at least there are good resources (LEF eg) to find the good ones.). Most doctors, even though they are MD’s, also offer quackery treatments (homeopathy is really big here). I have a doctor, who I go to the get prescription allergy medicine (which is OTC in the US), but that’s about it (I actually saw a brochure in the waiting room once about how angels help us heal). If I went to my doctor and asked her about Vitamin D treatment, she wouldn’t know what I was talking about.
        Anyway, I actually just went to a lab on my own and got these tests done – no doctor involved. I am now taking 7,000 IU’s (2,000 from the LEF mix plus I added 5,000). I guess I am a little reluctant to go to these high doses on my own, even though risk of toxicity is probably non-existent at my levels. I think I am going to put in some effort into finding a better doc (there’s got to be some).
        I am curious, since you mentioned a strength improvement. Something I have always had, is feeling extremely drained and fatigued the day after a hard gym session. I can do a lot of work, push myself hard etc, but it definitely affects me the next day. Could this also be related to the deficiency?

        • Monica 6 years ago

          If your doctor isn’t informed about the seriousness of vitamin D deficiency, get another one!
          Then I’d suggest you start with a loading period of 3 x 7000 IU per day for 4 weeks, then go down to 7000 IU per day for 6 weeks, and after that do another blood test.
          Maybe. But you will probably notice more during your workouts as your vitamin D levels start increasing.

  2. Miron 6 years ago

    Great article and very useful for many people (like many of other articles made by your and Will as well).
    By reading the article I found myself a little bit puzzled at the part:
    …”Vitamin D supplements come as either vitamin D2 (cholecalciferol) or vitamin D3 (ergocalciferol)”…
    I’m using D3 supplementation for last two years and it really made me wondering if I might read it wrong or it was just a typo mistake while you were typing the article. I’m using D3 (cholecalciferol) and when I checked about D2 it showed up as ergocalciferol, so I guess you can quickly correct that typo unless I’m dealing with wrong information and wrong impression and I would be more then grateful if you confirm it so I can update my “knowledge base” in my head 🙂
    p.s. can’t wait to see your next article about dosages so I can compare with the ones I’m using (until I get my blood test done to check the exact value).

    • Monica 6 years ago

      That was a typo, my bad. I just corrected it, should be:
      vitamin D2 (ergocalciferol)
      vitamin D3 (cholecalciferol)

  3. paulC 6 years ago

    You said “A recent study showed that vitamin D supplementation is actually more effective than advised sunlight exposure for treating vitamin D deficiency”
    Considering that foods are relative low in Vitamin D and that millions of years of evolution has our bodies producing vitamin D from sun exposure, should be an indicator where we should be getting our Vit.D. Hard to believe that mother nature loses out to synthetic vitamin D.
    Just a thought,
    Always enjoyed your articles.
    Keep them coming.

    • Monica 6 years ago

      Vitamin D deficiency was probably rare among our ancestors. The fact that it is on the rise means it is our modern lifestyle that is to blame.

    • Martin Havelka 6 years ago

      I have also thought about this and am curious why these deficiencies occur, even in the “surfer dudes”. Two things I could think of (just what I think could be a possibility, I don’t have data to verify it), is that food 100,000 years ago was probably more nutritious than today, and people literally spent the whole day outside, not just 22.4 hours per week. It wasn’t always in the sun of course, but it could still have been enough to make a difference.

  4. Lisa 6 years ago

    Monica, great article! You should really look into vitamin k2 to go with your follow up article. You should not take high doses of d3 without k2. I have been conducting a high dose d3 experiment on myself for the last 40 days because my levels were low. I am trying to bring my level to 60. I am taking 1 LEF super k for every 10,000 iu’s of d3 as recommended. I believe vitamin k will be the next big thing. It’s worth you looking into! Thanks, Lisa

    • Monica 6 years ago

      Yes, there’s an interesting synergy between vitamin K2 and Vitamin D, and calcium metabolism. And like you say, K2 is (like vitamin D) the subject of intense research, that deserves an article in its on right.
      I’d say it is more deleterious to supplement with calcium without K2, than vitamin D without K2. Of course, getting them all together is the best approach.

  5. Jeffrey 6 years ago

    How does the ng/mL translate into the i.u.’s listed on the vitamin label?
    Great artilcle by the way, as usual.

    • Monica 6 years ago

      As I will explain in my upcoming article; there is no clear-cut dose-response relationship between vitamin D intake and blood levels. The same dose can elevate blood vitamin D levels [ie 25(OH)D] to different degrees in different people. This is why it is so important to monitor your levels. But I will provide some guidelines.

  6. Gina 6 years ago

    Great article, look forward to reading the next instalment.

  7. Bo 6 years ago

    Will and Monica, Great info as usual. As a 59 yr. old guy I had my Vitamin D level checked 6 months ago and it was 19 (ref. range 33-100). My doc told me to take 1000 units of Vitamin D3 once a day. Last week I had a regular Dr. visit and had routine blood work done again. So after 6 months of taking 1000 units of Vitamin D once a day, my level was still only 21. My Dr. then said take 1000 units of Vitamin D3 twice a day. He neglected to say when to take them. I have read all your Vitamin D3 should be taken in the morning, with your largest meal but not at night because it can cause sleep disturbances.
    I know you are not doctors…but he is not a nutritionist. So can you suggest a typical dosage and the proper time(s) that people ordinarily take Vitamin D3 and get the best results so I can intelligently discuss it with him? Thanks!

    • Monica 6 years ago

      Thanks for sharing your experience. I will go into much more dept on dose-response in the follow-up article, but here is what I’d recommend somebody with a baseline of around 20 ng/mL:
      Start with a loading dose of vitamin D3: 28-30,000 IU/day for 15 days, then go down to 7-8,000 IU/day for 20 days. After that, get your vitamin D level checked again and adjust the dose based on your new reading.
      Vitamin can be taken anytime, but is best absorbed with fat rich meals. It’s highly unlikely that it will cause sleep disturbances. Being fat soluble, the dose can be taken either all at once (severe deficiencies are actually treated by injections of 50,000-100,000 IU, so you don’t have to worry about taking high doses at one time), or split up over the day. I though personally prefer to split the dose up over the day.

      • Bo 6 years ago

        Monica, Thanks for your prompt and thorough reply. Gee, 30,000units a day for 2 weeks SOUNDS high. Is there any danger of Vitamin D3 toxicity or overdose?

        • Monica 6 years ago

          Vitamin D has an extremely large safety margin;
          30,000 IU/day x 15 days = 450,000 IU in 15 days
          Deficiencies are safely and successfully treated with single loading mega-doses in the range of
          600,000 IU:
          Effect of a single oral dose of 600,000 IU of cholecalciferol on serum calciotropic hormones in young subjects with vitamin D deficiency: a prospective intervention study.
          Cipriani C, et al; J Clin Endocrinol Metab. 2010 Oct;95(10):4771-7
          Once you’ve got your level up to 50-60 ng/mL, a maintenance dose of 5,000-10,000 will keep you there. I will go into more dept on this in my follow up article.

          • Bo 6 years ago

            Ok, Thanks Monica.

    • Will Brink 6 years ago

      Did you listen to the radio show linked in the Monica’s article above? There’s plenty of additional info there. Follow her dosing advice. As you experienced the “high” doses you took, did very little for your levels. I take 5000IU per day, in addition what what I get in a multi and my food and some sun, and that gets me right in the 50-60 range.

      • Monica 6 years ago

        When it comes to vitamin D dosing, one has to distinguish loading dose (to elevate one’s vitamin D level) and maintenance dose (to keep the elevated level).

  8. Aimo Ruoho 6 years ago

    Thank you so verymuch for writing this email.
    What I was wondering though, was the fact, that you used
    measures, nt familiar to most persons onthe street.
    Please, would you explain the different measures used
    using micrograms, not those. millimoles or IUs, which are
    usually used by doctors and other people, who try to mix
    our thoughts to not see thetruth. It is very common to
    use milli- and micrograms, when speaking about vitamins
    in general, isn’t it? I had to look for those other measures
    from Wikipedia to understand anything, but it really would
    be more useful to common people to understand, to use
    one type of measures only.
    Thank you very much for your very beneficial articles,
    dear Monica.

    • Monica 6 years ago

      1 microgram vitamin D = 40 IU vitamin D
      10 microgram vitamin D = 400 IU vitamin D
      100 microgram vitamin D = 4000 IU vitamin D
      200 microgram vitamin D = 8000 IU vitamin D
      There you go.

    • Will Brink 6 years ago

      One type of measure would indeed be nice, but of course does not exist, even between scientists or doctors at times and across cultures (meters, ft, inches, gallons, ounces, etc, etc), so we still have to make those conversions to make sense of it from our own reference points.

  9. Cindy 6 years ago

    Thank you Monica for such an in depth and interesting article. I love your work and look forward to reading everything you write. I am in awe of your outstanding knowledge and so appreciate you passing it on. Look forward to the coming follow ups on this topic and and any others you write. Thank you and have a great day.

    • Monica 6 years ago

      Thanks Cindy; I’m glad you appreciate my work.

      • Mark 4 years ago

        So, was the follow-up ever published? If so, where?

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