The Importance of Vitamin D3 Compared to D2

The Importance of Vitamin D3 Compared to D2

Many people around the globe are low on vitamin D. We mainly get our vitamin D from the sun but there is D2 and D3 to consider.

However, there are variants of vitamin D. We take a look at both.

LAST UPDATED: April 2019 by Ben.

This article has cited references from reputable sources found at the footer of the page.

Deficient in D

Were you aware that 20% of the UK population are low on vitamin D?

That equates to around 13 million people. [1]

In fact the Public Health England government department recommends that the population take a vitamin D supplement. [2]

This could be for a number of reasons, an ageing population being one of them with 18% of the UK populace being over the age of 65. [3]

Plus, the UK is not exactly known for it’s long hours of sunshine throughout the year. That said, it is a myth that it rains all of the time.

In fact less than 50% of the year experiences rainfall with just 133 days of rain on average.

However, those places that experiences even less than that are known to be the “happiest” places to live. [4]

Vitamin D Study

However, it may not be quite as simple as just taking a vitamin D supplement, sure, it is probably the best advice to reach out to the majority of the population but there are a number of differing factors such as:

  • Gender
  • BMI
  • D3 or D2
  • Dosing schedule

These different factors can make a considerable difference to the way vitamin D supplements affect your body. [5]

Why Is Vit D Important?

Vitamin D is often overlooked or not even considered, especially compared to vitamin C.

Yet, vitamin D is extremely important for a number of bodily functions such as:

  • Cognitive function
  • Testosterone
  • Bone health
  • Organ health
  • Nerve health [6]

And it isn’t just the population of England that is suffering a deficiency either, the US and other parts of Europe are also suffering from what has been suggested as pandemic. [7]

In Boston, US it was discovered that almost a quarter of the population could be deficient.

A study conducted among 307 healthy, young adults in Boston revealed that 24.1% were deficient in vitamin D. [8]

It is considered that in the developing world, as much of 90% of the population could be deficient in vitamin D. [9]

D2 or D3

Yes, that’s correct, there are two types of vitamin D.

It is a common theory that D3 is the best form of vitamin D to supplement as it is absorbed better and, as a result, can improve vitamin D concentrations. [10]

D3 comes from sunlight plus some foods such as eggs (yolk) and oily fish.

Whereas D2 is produced by plants such as mushrooms.

We must theorize that the inconsistent historical data is partly down to the fact that every person is different and what may work exceptionally well for one person may not be replicated for another.

Therefore absorption data results have been skewed by a persons BMI, pre existing Vitamin D levels, gender plus how often they may already supplement with vitamin D.

A recent study conducted by the BioMed Central (BMC) illustrated that both forms of vitamin D are effective at increasing the levels of vitamin D in the body. [11]

This is measured by levels of 25-hydroxy D found in the body.

The study included 279 adults over a period of 140 days who received varying regimes of either vitamin D2 or D3.

Interestingly BMI seems to affect the responsiveness of D2, whereby D3 was the better and more effective option.


Females also responded better to vitamin D supplementation.

D2 is particularly more effective than when dosed daily as opposed to a 2 week or a 4 week regime, yet D3 is better absorbed in the 2 weekly and 4 weekly regimes than D2

However, a contemporary study conducted by the University of Surrey sought to settle the argument and demonstrated that D3 was responsible for increasing vitamin levels by 74-75% whereas D2 supplementation only increased body vitamin D levels by 33-34%. [12]

What is clear though is that, supplementation of either will be effective and will increase the levels of 5-hydroxy D which is required for improved bodily function and health.


If you live in a climate with limited sunshine, or you spend most of your time inside you should supplement your nutrition plan with a vitamin D supplement for the optimal health benefits.








[7] Vitamin D deficiency in Europe: pandemic? Cashman KD, Dowling KG, Škrabáková Z, Gonzalez-Gross M, Valtueña J, De Henauw S, Moreno L, Damsgaard CT, Michaelsen KF, Mølgaard C, Jorde R, Grimnes G, Moschonis G, Mavrogianni C, Manios Y, Thamm M, Mensink GB, Rabenberg M, Busch MA, Cox L, Meadows S, Goldberg G, Prentice A, Dekker JM, Nijpels G, Pilz S, Swart KM, van Schoor NM, Lips P, Eiriksdottir G, Gudnason V, Cotch MF, Koskinen S, Lamberg-Allardt C, Durazo-Arvizu RA, Sempos CT, Kiely M. Am J Clin Nutr. 2016 Apr;103(4):1033-44. doi: 10.3945/ajcn.115.120873. Epub 2016 Feb 10. PMID: 26864360



[10] Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Tripkovic L, Lambert H, Hart K, Smith CP, Bucca G, Penson S, Chope G, Hyppönen E, Berry J, Vieth R, Lanham-New S. Am J Clin Nutr. 2012 Jun;95(6):1357-64. doi: 10.3945/ajcn.111.031070. Epub 2012 May 2. Review. PMID: 22552031



Vitamin D2 versus D3
Article Name
Vitamin D2 versus D3
This article addresses the importance of vitamin D and whether D2 is as important as D3.

Ben BA(Hons), PGCert

Ben established this site to be a free resource in 2015. Since then it has gained over half a million visits. He has always been interested in sport and he started playing rugby at the age of 6 represented his town, county and school. Ben also enjoys cycling, has started skiing and is in the Army Reserve representing his Regiment as part of the 150 Regimental Shooting Team. He holds a bachelor's and postgraduate degree in sport exercise & nutrition.

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