Vitamin D3 And Calcitriol: Why The Difference Between The Two Is The Difference Between Strong and Weak Bones - Save Our Bones

You surely know by now how important Vitamin D3 is to building younger, healthier bones. But you may be surprised to learn that getting this essential vitamin to where it needs to go, in a form that your body can use, requires some additional steps.

You see, unlike other vitamins, before Vitamin D3 can perform its functions, your body must “activate” it by turning it into a hormone. This bioactivated version of the vitamin is called calcitriol. Additionally, calcitriol needs to connect with a specific receptor called the Vitamin D Receptor, or the calcitriol receptor.

When we talk about the benefits of Vitamin D3, we’re talking about the benefits of calcitriol, because unless it makes this transformation, it can’t be absorbed and used.

Today we’ll look at calcitriol’s important role in improving your bone health, its positive impact on the rest of your body, and how to increase calcitriol levels.

Calcitriol Has Many Benefits

Bioactivated Vitamin D3, or calcitriol, plays many important roles in the human body. It has been shown in medical studies1 to protect against a litany of issues including:

  • Asthma
  • Cancer
  • Diabetes – Type 1 and 2
  • Heart disease
  • Infections
  • Multiple sclerosis
  • Neurological diseases
  • Psoriasis

The most relevant benefit for Savers of course, is protection against Osteoporosis, through the building of stronger bones.

How Does Calcitriol Function?

One major function of calcitriol is to connect with the Vitamin D Receptors (VDR) mentioned earlier. These VDRs, once they’ve bound with calcitriol, flip a genetic switch in your DNA. This switch, when flipped to the ‘on’ position, allows your intestines to absorb calcium by stimulating the expression of special proteins that carry it across the intestinal wall.

Otherwise it would escape your body without ever getting used! Only after calcium enters the bloodstream, it becomes bioavailable to build new bone.

If this were the only function of calcitriol, it would already rank as possibly the most important hormone at work in bone health. But this activated form of Vitamin D does even more.

Beyond Calcium Absorption

Calcitriol also regulates the creation of bone matrix proteins, mineralizing the collagen matrix in bone. This is incredibly important to building high quality, fracture-resistant bones. Savers know that when it comes to bone health, quality over quantity is the difference between strong pliable bones and thick brittle ones.

It also facilitates the out-with-the-old and in-with-the-new process of bone formation by stimulating osteoclast differentiation and calcium reabsorption of bone.1

But That’s Not All

Calcitriol has additional health benefits, such as reducing inflammation by lowering the “adaptive” immune system, while stimulating the parts of your immune system that control viral infections and help prevent autoimmune disease.2

Your immune system’s T-cells, the cells that actively fight infections, require calcitriol to activate in order to do this work. In fact, they actually seek out bioactivated Vitamin D3.3

Gene Expression

The Vitamin D Receptors that enable your gut to absorb calcium also regulate many other important bodily functions. One VDR benefit is the activation of liver and intestinal enzymes that help your body to metabolize drugs and toxins. Our world is full of toxins that we absorb and ingest, try as we might to avoid them, so this process in incredibly important.4

Calcitriol and VDR also secrete a chemical in parts of your brain5 that increases the production of dopamine, adrenaline and noradrenaline;6 neurotransmitters that help your brain function and even improve your mood.

Additionally, there are studies showing that the enzyme that breaks down calcitriol has a positive impact on breast7 and lung cancer8, an encouraging association that suggests that activated Vitamin D facilitates this benefit.

6 Ways To Increase Your Calcitriol Levels

  1. Exercise has been shown to increase the activation of Vitamin D3.9 Of course Savers know that exercise also has a valuable positive impact on bone health for a multitude of other reasons.
  2. Omega-3 is an essential fatty acid and a powerful antioxidant with a bevy of health benefits from immune system support to decreased depression.10 For bone health, Omega-3 increases calcium absorption and reduces bone loss, helping to maintain optimal bone density. The highest food sources of omega-3s are salmon, sardines, mackerel, herring, trout, and snapper.
  3. Studies also reveal that Omega-6 increases calcitriol levels,10 but be wary of consuming too much of this fatty acid mainly found in processed foods and some vegetable oils. Western diets tend to consume too much Omega-6 in relation to Omega-3.
  4. Curcumin, a component of the common spice tumeric, also has been shown to increase calcitriol levels.11
  5. Vitamin E, an important antioxidant, keeps your VDRs available for calcitriol to use.10 You can increase your Vitamin E intake by consuming a variety of foods including sunflower seeds, greens (including kale), avocados, almonds, hazelnuts, broccoli, mango, and olive oil.
  6. Avoid excessive caffeine, since it decreases your body’s production of Vitamin D Receptors, preventing calcitriol from providing its most direct benefit, the absorption of calcium.12

Am I Already Calcitriol Deficient?

Everyone’s body is a little different, and because Vitamin D production happens naturally in the body mostly through sun exposure, where you live can impact your calcitriol levels as much as what you do.

Fortunately there are easy to recognize warning signs that you’re lacking in Vitamin D3:

  • Chronic pain and muscle weakness
  • Magnesium deficiency
  • Impaired or low immunity
  • High blood pressure
  • Sadness and depression, especially when seasonal
  • Age (older than 50)

I cover these indicators and how to identify them in more detail here: 6 Little Known Signs You Might Be Vitamin D Deficient.

Getting The D3 You Need

So now we’ve looked at what calcitriol is, what it does, and how it works. I’ve also listed some useful and simple ways to naturally increase your calcitriol levels and the functioning of your Vitamin D Receptors.

But if you recognize yourself in those Vitamin D deficiency signs, or you aren’t sure that you’re getting the daily required amount, you should be taking a Vitamin D3 supplement.

This is very different from a Vitamin D2 supplement. Never take Vitamin D2, which doesn’t offer the benefits of D3. Read more about the significant differences here.

I recommend taking at least the baseline 400IUs of D3 and increasing from there, depending on your sun exposure and skin tone. The Upper Intake Limit is 4000IU, so there is lots of personalization possible to get the right balance of naturally produced D3 and supplements. For strong and rejuvenated bones, you can take a minimum of 1000 IUs daily without worrying about overdosing. Read my article about identifying your personalized Vitamin D3 needs to learn more.

Calcitriol And Younger Bones

At the Save Institute we firmly believe that knowing how your body works is the first step to being able to keep it healthy. You can’t build younger bones if you don’t know how your bones get built. Today you learned about activating the Vitamin D3 you naturally produce or supplement so that it becomes calcitriol, which unlocks your body’s ability to absorb calcium.

We are a complex organism, with many interrelating systems, but at the end of the day, we can improve our health and our lives through a simple combination of best practices that include clinical nutrition, science-based supplementation, and exercising.

That’s why I created the Osteoporosis Reversal Program, so you could have an easy-to-follow blueprint that provides not just what you should do, but all the answers on why it’s the best way to build a younger you, including your bones.

Stop Worrying About Your Bone Loss

Join thousands of Savers from around the world who have reversed or prevented their bone loss naturally and scientifically with the Osteoporosis Reversal Program.

Learn More Now →

Till next time,


1 Feldman, David, et al. “The role of vitamin D in reducing cancer risk and progression” Nature Reviews Cancer. (2014). 14. 342–357. DOI: 10.1038/nrc3691. Web:

2 von Essen et al. “Vitamin D controls T cell antigen receptor signaling and activation of human T cells.” Nature Immunology, 2010; Web:

3 Cantorna MT. 1, Zhao J, Yang L. “Vitamin D, invariant natural killer T-cells and experimental autoimmune disease.” Proc Nutr Soc. 2012 Feb;71(1):62-6. doi: 10.1017/S0029665111003193. Web:

4 Reschly and M.D. Krasowski. “Evolution and Function of the NR1I Nuclear Hormone Receptor Subfamily (VDR, PXR, and CAR) with Respect to Metabolism of Xenobiotics and Endogenous Compounds.” Curr Drug Metab. 2006 May; 7(4): 349–365. Web:

5 Cui X, Pertile R, Liu P, Eyles DW. “Vitamin D regulates tyrosine hydroxylase expression: N-cadherin a possible mediator.” Neuroscience. 2015 Sep 24;304:90-100. doi: 10.1016/j.neuroscience.2015.07.048. Epub 2015 Jul 23.

6 Darryl W. Eylesa, Steven Smithb, Robert Kinobeb , Martin Hewisond, John J. McGratha. “Distribution of the Vitamin D receptor and 1a-hydroxylase in human brain.” Journal of Chemical Neuroanatomy. 29. (2005). 21–30.

7 Lopes N1, Sousa B, Martins D, Gomes M, Vieira D, Veronese LA, Milanezi F, Paredes J, Costa JL, Schmitt F. “Alterations in Vitamin D signalling and metabolic pathways in breast cancer progression: a study of VDR, CYP27B1 and CYP24A1 expression in benign and malignant breast lesions.” BMC Cancer. 2010 Sep 11;10:483. doi: 10.1186/1471-2407-10-483.

8 Chen G, Kim SH, et al. “CYP24A1 is an independent prognostic marker of survival in patients with lung adenocarcinoma.” Clin Cancer Res. 2011 Feb 15;17(4):817-26. doi: 10.1158/1078-0432.CCR-10-1789. Epub 2010 Dec 17.

9 Zittermann A1, Sabatschus O, et al. “Exercise-trained young men have higher calcium absorption rates and plasma calcitriol levels compared with age-matched sedentary controls.” Calcif Tissue Int. 2000 Sep;67(3):215-9.

10 Haussler MR1, Haussler CA, Bartik L, Whitfield GK, Hsieh JC, Slater S, Jurutka PW. “Vitamin D receptor: molecular signaling and actions of nutritional ligands in disease prevention.” Nutr Rev. 2008 Oct;66(10 Suppl 2):S98-112. Doi: 10.1111/j.1753-4887.2008.00093.x.

11 Haussler MR1, Whitfield GK, Kaneko I, Haussler CA, Hsieh D, Hsieh JC, Jurutka PW. “Molecular mechanisms of vitamin D action.” Calcif Tissue Int. 2013 Feb;92(2):77-98. doi: 10.1007/s00223-012-9619-0. Epub 2012 Jul 11.

12 Rapuri PB1, Gallagher JC, Nawaz Z. “Caffeine decreases vitamin D receptor protein expression and 1,25(OH)2D3 stimulated alkaline phosphatase activity in human osteoblast cells.” J Steroid Biochem Mol Biol. 2007 Mar;103(3-5):368-71. Epub 2007 Jan 12.

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Comments on this article are closed.

  1. Diann

    I wish you had discovered this just a few months earlier I lost my mom to heart problems😪

  2. Benni

    Hi Vivian, I checked my vitamin D level and the result was 8.7. My doctor prescribed calcitriol 0.5 mcg (twice a day) for 2 weeks and it increased to 10.1 only. Should I increase tjw dose to three times a day? Is calcitriol similar with cholecalciferol? Should I move to cholecaciferol instead of calcitriol?

  3. Vinod

    I had severe low back pain for 5-7 years. After self checking I found my vit-d3 level was 4. I was given vit-d3 60k dose per week for 4 weeks.
    After 6 months I tested and found level as 4.5 again ! I am given 60k vit-d3 weekly and daily tablet of calcitriol 0.25 mcg and calcium 1250mg along with zinc, vit k2-7, magnesium.

    I read somewhere that calcitriol should not be taken with vit-d3. Plz suggest.

  4. Sally Wells

    My doctor prescribed D3-50 50,000 units to be taken once every 7 days. I read all of the side effects and so I have not taken the RX yet. I was already taking D3 from over the counter vitamin shelf. Do you know if this RX is really safe?
    FYI: I have COPD and athrosclerosis. (spelling might not be correct)

    • Vivian Goldschmidt, MA

      Hi Sally,

      I don’t recommend mega-doses of Vitamin D, and here’s why.

      We know that we need vitamin D, we also know that we get it mostly from the sun (ideal) and from supplements (less ideal, but necessary). We also know that it’s a fat soluble vitamin, which means that it accumulates in the body.

      There really is no cookie-cutter recommendation for everyone, since each of us spends time in the sun for varying times (or no time at all). Hence, and with the knowledge that you can always safely take the RDA of 400 IUs, you can build from there depending on the seasons and your exposure to the sun.

  5. shulamit sendowski

    Thank you for this informative message on D3!

  6. Lisa

    Hi Vivian,
    I recently began taking True Osteo, as recommended by you. But I have noticed that my pH balance is not in the alkaline range since starting this supplement. I have taken it for nearly two months. Shouldn’t this be the measurement by which we can know that our bones are not being leached calcium? I am contemplating returning the supplement but would like your input on the results I am getting. Thank you!

    • Vivian Goldschmidt, MA

      Hi Lisa,

      Your body’s pH is influenced by a number of factors, not just the calcium supplement you are taking. In fact, I don’t recommend checking the pH regularly because it fluctuates greatly depending on the time of the day and other factors such as stress, level of physical activity, even sweating. However, should you wish to check it every once in a while, a pH of around 6.2 to 6.4 measured first thing in the morning from saliva and/or urine is considered a good level.

  7. Ken Switzer

    When taking D3 shouldn’t one also alwasy take Vitamin K2 with MK7?

    • Vivian Goldschmidt, MA

      Hi Ken,

      Good question! You’re on the right track – bones are built by many nutrients working in synergy, and it’s important not to focus too heavily on a single vitamin or mineral.

      That said, Vitamin K is another vital nutrient for building bone, and you are right that it works with Vitamin D: “Vitamin K is related to osteocalcin, also called bone Gla protein, which is a calcium-binding protein synthesized by osteoblasts or bone-building cells. It also works synergistically with vitamin D to regulate the production of osteoclasts, cells that remove old bone so that new bone can be deposited in its place.”

      That quote is taken from a post on Vitamin K; you can read the entire post here:

  8. Alma McNamara

    Vivian, you had recently written about why soy milk was not good for our bodies. I’ve forgotten the reasons why, so would you please inform us again?

    Thank you,

    Alma McNamara

  9. Carol

    Thank you Vivian for this great information. I’ve been concerned about the Vitamin D2 found in all almond milk and after reading this article I’m not sure about continuing to drink it. I often like to switch to lactaid milk which contains Vitamin D3. Thanks again!

    • Vivian Goldschmidt, MA

      Hi Carol,

      I understand your concern about D2 being added to foods and beverages, including almond milk. If you want a completely additive-free almond milk, it’s actually fairly easy to make it yourself. All you need is a blender, raw almonds, and pure water. 🙂 There are many recipes online; the process essentially involves whizzing the almonds and hot water in the blender, allowing it to steep, and filtering out the almonds.

      • Carol

        Thanks Vivian, that sounds like a great idea. I’m going to try making some and will let you know how it works out for me. I don’t know the reason why they can’t just add Vitamin D3 to the almond milk instead of Vitamin D2? Thank you.

  10. Marion Thomson

    I recently had my Doctor check my blood
    My Hemoglobin is LO-117
    Hematocit is LO 0.345
    RBC is LO 3.86
    I would appreciate help to change my
    diet to rectify these readings.

  11. Dora Costa

    I was taking 1000 D3 per day then doubled that after blood work showed too low. Doubled that to 2000 per day and still too low. Now I am taking 4000. But, I want to know what brand is a good quality D3.?

    • Simon Prowse


      Surely you must be an angel.

      Thank goodness we have people like you to help us manage our health.


    • Vivian Goldschmidt, MA

      Hi Dora,

      There is not a particular brand that I am recommending at this time, but here are some guidelines about Vitamin D supplementation taken directly from a previous blog post:

      “Blood levels between 40 and 70 ng/mL are associated with decreased risk of disease and healthier immunity, so those are the levels you should aim to get. However, given the importance of Vitamin D on so many body systems, 2000 IU is the ideal daily D3 dosage, especially in cold and dark winters.

      A note on sunlight – you can’t overdose on Vitamin D if you get it from sun, so if there is any possible way to get your skin exposed to sunlight during the winter months, I highly recommend that you do. It’s simply the best way to get the Vitamin D you need. But if not, oral doses of Vitamin D3 (cholecalciferol) are a more bioavailable form than straight Vitamin D.”

      You can read the whole post here:

      • Fox

        If your Vitamin D levels are low, taking 2000IU a day is simply to low. I think your numbers on Vitamin D supplementation are off. All experts recommend much higher doses than those suggested here. I have been taking 10,000 IU daily for months to bring up my levels along with 100mg Vitamin K2, a daily dose of Raw Calcium (which also has 100mg K2 in it) Magnesium Malate and although not daily, Raw Q10 which has some trace minerals in it. My levels have come up, but not to where I want them to be. Check out The Vitamin D Council for dosing guidelines as it will be helpful to those with low D trying to bring their levels up. The key is not taking D3 alone, but the cofactors, like I do. Hope this helps.

        • amin

          Absolutely correct. The amounts being recommended here are much too low.
          if you spend 15 minutes in a bathing suit in the son – you make 25,000 iu’s of vitamin D

          400iu’s is nothing
          infants should be on 600 to 800iu’s and adults on a minimum of
          2000iu daily if further than 20 degrees from the equator. I live in Toronto and give my whole family 5000iu daily. get your values tested. Take a combination of cod liver oil and vitamin D3+K2 1000/120 and just make sure that the total amount of vitamin D is somewhere in the range of 3-5000iu daily is my suggestion

  12. becky

    Vivian, my done density results came back as osteoporosis. I am 57 and went thru menopause at 50. I am active and do not take any medications, other that vitamin supplements. My Dr recommended Fosimax, I don’t not want to take that as I have read negative things about it. I have been following your website for a while. What would be your recommendation other that the Fosimax?-thank you

  13. Patti

    Vivian — For several years, when having blood tested during my annual exam, my calcium levels are high and vitamin d low. I have been taking both supplements on a regular basis. My Dr suggested stopping the calcium and increasing vitamin D. Upon researching I found that my symptoms describe a parathyroid tumor (especially at my age of 76). The article stated “taking vitamin D with high blood calcium can be dangerous”. What is your advice?

    • Vivian Goldschmidt, MA

      Hi Patti,

      If you are concerned about your parathyroid, then by all means, ask your doctor about testing. If there is a problem, it’s best to find out earlier rather than later. 🙂

    • carmen carroll

      how does it help psoriasis?

  14. Mary

    My dexa results a couple of months ago weren’t great, which prompted buying items on this site. My doc approved an over the counter multi-vitamin I had purchased but also tested my vitamin D levels which were low. She recommended 5000 IU of D3 a day.

    I’m using a suppliment to get to 4000 a day ( I think the 5000 may be excessive) and going back to have it checked in a couple of months. As I live in Fl I try to get 15 hours of sun at noon each day – can be a struggle based on my schedule. I have also read there is a vitamin d3 sunlamp.

    As an aside can’t say enough about this program – both diet and exercise. Most exercises in the program are similar to what I do in yoga, which I had coincidentally started 6 months ago, so I do them on non-yoga days.

    • Vivian Goldschmidt, MA

      It sounds like you are on the right track, Mary. And remember, scan results only show part of the picture – they reveal how much bone is there, but they can’t show the quality of bone or its tensile strength. Since you’ve been following the Program, chances are your bones have very good tensile strength, which is the true indicator for fracture resistance.

      Also, just to check – I assume you’re trying to get 15 minutes, not hours, of sunlight a day. 🙂 That’s a good plan, and if you can’t do it some days or only get a few minutes, that’s okay.

  15. SJ Davis

    But also, why not sensible sun exposure for as much of the year as possible? I believe done regularly during warmer months (geography dependent, of course), one can even build up a certain amount of reserve. Then use supplements as the next line of defense.

    • Vivian Goldschmidt, MA

      I agree wholeheartedly, SJ. That’s a very balanced and healthful approach, which you’ll find to be consistent with the Save Our Bones recommendations about Vitamin D. 🙂

  16. Patty

    Shane Ellis, The People’s Chemist, has stated that Vitamin D3 is being processed from Sheep’s wool, and my understanding is that he implies this is not healthy for humans to take. Other than natural sunlight, which isn’t possible since I live close to the Canadian border, how does one acquire natural Vitamin D3? Thank you!

    • Vivian Goldschmidt, MA

      Hi Patty,

      Of course, sun exposure is the best way to obtain Vitamin D3 naturally; but if you feel you need to supplement and sheeps’ wool as a source is a concern for you, then your best bet is to do an internet search for “vegan D3” and explore the available options.

  17. Barbara

    Hello Vivian,

    I am so delighted to report that I have increased my bone density over two and a half yrs by 3.8per cent.!! My results record this as a significant increase.
    I am so happy to have done this without any drugs and want to thank you so much for your support and wise advice. I would have been lost otherwise and would probably be taking Prolia by now which was recommended not knowing the damage I would be doing. I was repeatedly told I would not be able to improve by myself.

    I use natural plant and algae based supplements, I exercise (walking and pilates) and eat a balanced diet with lots of greens (kale etc). As much as I can I try to follow this routine with ups and downs.
    I hope that I can continue to improve at this rate and in another couple of yrs be out of the osteoporosis range.
    Thank you again for all your help and encouragement.

    Barbara (from Ireland)

    • Vivian Goldschmidt, MA

      Barbara, I can’t thank you enough for taking the time to share this with the community. It is so encouraging to hear of other Savers’ success! I love how you defied the repeated “advice” that you would not be able to improve on your own. Congratulations!

  18. shardamata satyam

    Vivian, why not just advise people to take some or all of their D3 supplement in the form of calcitriol, the activated form of vit d3, instead of just taking it all in the more normal supplemental form of vit d3 which is cholecalciferol?

    • Jan

      Good idea. And why not suggest reliable brands here?

    • Vivian Goldschmidt, MA

      Excellent question, Shardamata. In fact, research suggests that either form of supplementation, calcitriol or cholecalciferol, is effective at raising Vitamin D levels. Here is a link to a Chinese study that compares the two forms of Vitamin D in post-menopausal women:

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