Calcifediol | Vitamin D3 2000 IU Tablets

VitamoreD delivers Calcifediol (25-hydroxyvitamin D3), the form your blood test measures. One easy-to-swallow tablet with a 93% absorption rate.

Traditional Vitamin D supplements are focused on cholecalciferol, which requires conversion in your liver to become Calcifediol. VitamoreD contains Calcifediol, also known as 25(OH)D or 25-hydroxyvitamin D. The form that circulates in your blood, the form that blood tests measure. Same benefits as traditional vitamin D3 but faster-acting and with more predictable and measurable results.

• Increase vitamin D levels in days, not weeks: Calcifediol skips the liver conversion (Calcifediol doesn't require hepatic 25-hydroxylation). Vitamin D 25(OH)D levels rise faster, which is what your blood test measures.
• Immune Function: Vitamin D contributes to the normal function of the immune system. Your immune cells carry vitamin D receptors (VDR) and depend on circulating Calcifediol to switch on that vitamin D response.
• Muscle Function: Vitamin D contributes to normal muscle function. Vitamin D receptors (VDR) sit in muscle fibres and their density falls with age.
• Calcium and Phosphorus: Vitamin D contributes to absorption of calcium and phosphorus. We need calcium and phosphorus because they combine to build strong bones and teeth. Calcium drives muscle movement, nerve signals, and heart function, and phosphorus powers cellular energy (ATP) and supports DNA. Absorbing them together is important because they balance each other in the blood and rely on adequate vitamin D levels for absorption and uptake.

For raising your blood vitamin D level, randomised trials show that 1 microgram of calcifediol vs 1 microgram of cholecalciferol: calcifediol is more potent, works faster and raises vitamin D levels more predictably. This is because, when supplemented, calcifediol, unlike cholecalciferol, is not pulled into the adipose (fat) tissue. Cholecalciferol is lipophilic, so taking high doses doesn't guarantee conversion, as it can be pulled into adipose tissue and stored; therefore, there is potential to overcompensate and overcorrect. Whereas calcifediol is more hydrophilic, vitamin D levels increase more linearly, microgram to microgram. So why wouldn't you supplement with calcifediol, the form we measure in tests, over traditional cholecalciferol D3?

Vitamin D isn’t actually a vitamin; it’s a prohormone that goes through a two-step conversion process called hydroxylation before your body can actually use it and feel its benefits. All these studies on the benefits aren’t about cholecalciferol; they’re about calcitriol.

Calcifediol is the form of vitamin D that has already gone through that first step of hydroxylation. Calcifediol is also the exact molecule a blood test measures. Calcifediol is the step before activation, unlike cholecalciferol, which still requires two more steps: absorption and conversion in the liver (hydroxylation).

VitamoreD delivers Calcifediol in one easy-to-swallow tablet with rapid absorption and sustainable and measurable vitamin D levels.

The three-step process for vitamin D to convert and work

1. Cholecalciferol (Vitamin D3): The form made by the skin when exposed to UVB sunlight rays, or the form taken as a traditional D3 supplement. This is the form of vitamin D also stored in body fat. Vitamin D as cholecalciferol is inactive and needs to be converted twice to become the form of Vitamin D (Calcitriol) that delivers the health benefits vitamin D research suggests.
2. Calcifediol 25-(OH)D3: The circulating form of vitamin D3, the form screened and measured in your blood test by your GP and practitioner to show if you have too much or too little vitamin D. This is the form of D3 that practitioners refer to as your “vitamin D level” and is the form delivered by VitamoreD in an easy-to-swallow supplement. To become this form, cholecalciferol must first be converted by the CYP2R1 gene in the liver. 
3. Calcitriol 1,25(OH)2D3: The active hormonal form of vitamin D that is created when Calcifediol is converted in the kidneys. Calcifediol is the form of vitamin D that provides the benefits of vitamin D, i.e., mood, energy, bone and joint health, and immunity.

Calcifediol is measurable, targeted and increases vitamin D levels faster. The problem with traditional Cholecalciferol supplements is that they require fat, or adequate amounts of cholesterol, if you are trying to synthesise vitamin D from the sun. But it still needs to be converted by the CYP2R1 gene in the liver. This gene conversion in the liver can be reduced and even suppressed, especially in people who have chronically deficient vitamin D levels, are obese, are fasting and/or have type 1 or type 2 diabetes. This is why Calcifediol exists: it bypasses this step, doesn’t require liver conversion, is fat-soluble, and doesn’t care about your weight or any condition you are suffering from. 

Per 1 easy-swallow VitamoreD tablet:

• 10 mcg (1000 I.U.) Dyna-Cal 25-OH Vitamin D3 (Calcifediol).

Natural Ingredients: Cellulose, Magnesium salt of fatty acids (sourced from sustainable palm oil).

Gut-Friendly Coating: Hydroxypropylmethyl Cellulose (HPMC) and Ethyl Citrate for stability, integrity and improved absorption.

Vitamin D Potency - I.U. of Calcifediol

Vitamin D Potency is defined in International Units (I.U.). Research shows that the form of Vitamin D in VitamoreD (Calcifediol, also known as Calcidiol or 25-hydroxy D3) can be 3.2 to 5x more potent than cholecalciferol because of how it works and activates in the body. In 2024, the EFSA re-evaluated Calcifediol and agreed on the following:

Cholecalciferol in International Units.

• 1 mcg (µg) of Cholecalciferol = 40 I.U.
  
• 10 mcg of Cholecalciferol = 400 I.U.

Calcifediol in International Units.

• 0.4 mcg (µg) of Calcifediol = 40 I.U.
  
• 10 mcg of Calcifediol = 1000 I.U.

Why Calcifediol was originally 2000 IU per 10 mcg tablet.

When we launched in 2023, you may have seen 10 µg of calcifediol described as 2,000 IU, including on earlier versions of this page and on our current VitamoreD supplement. That figure was not invented. EFSA's 2021 opinion used a conversion factor of 5, borrowed from its own animal-feed panel, as a theoretical calculation, and 10 µg x 5 = 50 µg, which equated to D3 as Calcifediol = 2000 IU. The Commission then asked for the factor to be derived properly from human data. EFSA ran the systematic reviews and, in 2023, replaced 5 with 2.5 for labelling purposes. The number was halved because the science improved, and we follow the current figure.

How Vitamin D is converted and activated

1. Cholecalciferol (Vitamin D3): The form made by the skin when exposed to UVB sunlight rays, or the form taken as a traditional D3 supplement. This is the form of vitamin D also stored in body fat. Vitamin D as cholecalciferol is inactive and needs to be converted twice to become the form of Vitamin D (Calcitriol) that delivers the health benefits vitamin D research suggests.
   
2. Calcifediol 25-(OH)D3: The circulating form of vitamin D3, the form screened and measured in your blood test by your GP and practitioner to show if you have too much or too little vitamin D. This is the form of D3 that practitioners refer to as your “vitamin D level” and is the form delivered by VitamoreD in an easy-to-swallow supplement. To become this form, cholecalciferol must first be converted by the CYP2R1 gene in the liver. 
   
3. Calcitriol 1,25(OH)2D3: The active hormonal form of vitamin D that is created when Calcifediol is converted in the kidneys. Calcifediol is the form of vitamin D that provides the benefits of vitamin D, i.e., mood, energy, bone and joint health, and immunity.

Scientific References

1. Pérez-Castrillón JL, Dueñas-Laita A, Brandi ML, et al. Calcifediol is superior to cholecalciferol in improving vitamin D status in postmenopausal women: a randomized trial. J Bone Miner Res. 2021;36(10):1967–1978. PMID: 34101900 - https://pubmed.ncbi.nlm.nih.gov/34101900/
2. Cashman KD, Seamans KM, Lucey AJ, et al. Relative effectiveness of oral 25-hydroxyvitamin D3 and vitamin D3 in raising wintertime serum 25-hydroxyvitamin D in older adults. Am J Clin Nutr. 2012;95(6):1350–1356. Am J Clin Nutr 2012;95(6):1350–1356. - https://www.sciencedirect.com/science/article/pii/S000291652302823X?via%3Dihub#cited-by
3. Bischoff-Ferrari HA, Dawson-Hughes B, Stöcklin E, et al. Oral supplementation with 25(OH)D3 versus vitamin D3: effects on 25(OH)D levels, lower extremity function, blood pressure, and markers of innate immunity. J Bone Miner Res. 2012;27(1):160–169.. PMID: 22028071 - https://pubmed.ncbi.nlm.nih.gov/22028071/
4. Graeff-Armas LA, Bendik I, Kunz I, Schoop R, Hull S, Beck M. Supplemental 25-hydroxycholecalciferol is more effective than cholecalciferol in raising serum 25-hydroxyvitamin D concentrations in older adults. J Nutr. 2020;150(1):73–81 PMID: 31518424 - https://pubmed.ncbi.nlm.nih.gov/31518424/ 
5. Jetter A, Egli A, Dawson-Hughes B, et al. Pharmacokinetics of oral vitamin D3 and calcifediol. Bone. 2014;59:14–19 PMID: 24516879 - https://pubmed.ncbi.nlm.nih.gov/24516879/
6. Vaes AMM, Tieland M, de Regt MF, Wittwer J, van Loon LJC, de Groot LCPGM. Dose-response effects of supplementation with calcifediol on serum 25-hydroxyvitamin D status and its metabolites: a randomized controlled trial in older adults. Clin Nutr. 2018;37(3):808–814. PMID: 28433267 - https://pubmed.ncbi.nlm.nih.gov/28433267/
7. Shieh A, Ma C, Chun RF, et al. Effects of cholecalciferol vs calcifediol on total and free 25-hydroxyvitamin D and parathyroid hormone. PMID: 28187226 - https://pubmed.ncbi.nlm.nih.gov/28187226/

Written and reviewed by Tracey Raye, Nutritionist & Co-founder | MSc Personalised Nutrition.

Last reviewed 22nd October 2026. Next review: October 2026

Take 1 tablet daily, with or without food, in the morning.

Important information and recommendations:

1. Take with or without food: Unlike traditional cholecalciferol, you do not need to take VitamoreD (Calcifediol) with food that contains fats.
2. Take daily: Calcifediol has a half-life on average of 15 days (2 weeks); therefore, consistency matters.
3. Take daily, not weekly: Intermittent high-dose calcifediol can push 25(OH)D above the physiological range in a way daily dosing does not. Consistency is key to feel the benefits and avoid overshooting.
4. Retest at 12 weeks: In research, Calcifediol 25(OH)D (25-Hydroxy-D3) increased vitamin D levels within a few days, not just weeks. So, if you tested low and began supplementing VitamoreD, it’s important to re-test to monitor levels and see how you are doing.

What to add to improve Vitamin D activation

• Vitamin K2 as MK4 and MK7: Routinely taken with Vitamin D to support calcium-handling pathways (See VitamoreD plus)
• Daily 5 in 1 Magnesium: the hydroxylase enzyme in the kidneys relies on magnesium to help convert Calcifediol. If your magnesium intake is low, let’s be honest, most of us are! Then add the Daily 5 in 1 whole-body magnesium. 5 magnesium forms designed to restore magnesium levels, with B6 to activate absorption and conversion.
• Calcium: Vitamin D supports the absorption of calcium. If you have a low-calcium diet, then it’s important to work with your practitioner to adjust your diet or to find the right supplement for you.