Daily health

Vitamin D vs D3: What’s the Difference?

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Medically approved by Dr Earim Chaudry
Chief Medical Officer
iconLast updated 4th May 2021

In 30 seconds…

What’s the difference between Vitamin D and D3? In a country where about 20% of us have low levels of the so-called “sunshine vitamin”, it’s an important question. Particularly when it is key to keeping your muscles and bones in good shape.

Simply, Vitamin D is not just one single nutrient, but rather a group of similar vitamins that are chemically related. Vitamin D2 and Vitamin D3 are the varieties that we usually take in supplements, and, while slightly different, they are both forms of Vitamin D.

If you are weighing up the differences of Vitamin D2 vs D3, know that D3 is generally thought to be more effective in improving your overall Vitamin D levels. However, sourced only from animal products, it is not available for all of us.

Introducing Vitamin D and D3

In the UK, about one in five adults are thought to be living with low levels of Vitamin D. Meanwhile, 16% of the nation’s children are believed to have a deficiency. These are big numbers – yet it is not a problem limited to the UK. Rather, researchers have dubbed Vitamin D deficiency a “major global public health problem”.

However, despite the panic, if you have been researching how to keep your Vitamin D levels up, you may have found this essential fat-soluble vitamin to be a little more complex than it first appeared. There is no single Vitamin D, but a number of different vitamins that fall into this group.

In this article, we’re going to investigate one of these in particular. That’s Vitamin D3. So, Vitamin D vs Vitamin D3: what’s the difference? And which is better? Let’s take a look.

So, What is Vitamin D?

Vitamin D is one of the most well-known of the vitamins – and its fame primarily comes from its relation to sunlight. Whilst it is available in a small number of different foods and in supplements, Vitamin D is primarily produced by the skin when it is exposed to the sun.

However, in the winter months, many of us in the north do not get the exposure to the sun that we need to produce healthy blood levels of the vitamin. If we wear thick sunscreen, the same risk applies. As a result, the healthy functioning of our bodies can become impaired.

This is because Vitamin D facilitates some crucial processes in the body. Firstly, it regulates the amount of other essential minerals we have, such as calcium and phosphate – nutrients that are important for dental, muscular, and bone health. Without enough Vitamin D, for example, you are at risk of diseases such as rickets.

Yet, it may have a much larger range of effects, too. Research has suggested that it helps to regulate your mood and to ward off depression – and that it is important to fighting disease too. Other studies, by the way, have drawn a link between Vitamin D and erectile function and testosterone levels. 

Vitamin D vs D2 vs D3?

As we mentioned, however, there is actually no single Vitamin D. Rather, this is the name for a family of different vitamins that all have similar chemical structures.

The best-known of these are Vitamin D2 and Vitamin D3, and these are what you are most likely to encounter if buying Vitamin D supplements. But, with their slightly less catchy chemical names – ergocalciferol and cholecalciferol for D2 and D3 respectively – there are important differences between the two.

The first important difference is the source from which they derive. D3 comes from animal sources – including from fatty fish such as salmon, herring, sardines, and mackerel, and from liver, egg yolks, and butter. D2 on the other hand comes from plant sources exclusively, such as from mushrooms grown under UV light. Fortified foods, such as orange juice and breakfast cereals, can be sources of either form of Vitamin D.

But D2 is generally cheaper to produce – and it is therefore this variety that is primarily found in supplements. Whilst you can find D3 supplements, these don’t tend to be suitable for vegans – on account of the fact that D3 is only produced in animal products.

Importantly, it is D3 that is produced by your skin when exposed to sunlight. You are, after all, an animal yourself.

Vitamin D vs Vitamin D3: Which is Better?

Whilst they are incredibly similar in chemical terms, there is an important distinction between D2 and D3 that suggests that the latter is slightly superior. This is that Vitamin D3 has been found to be more effective in increasing the body’s overall levels of calcifediol, the active compound that circulates in your body and produces the desired effects associated with Vitamin D.

This chemical is the metric doctors use to measure your Vitamin D status, too.

What you need to know is that the Vitamin D that you receive through the sun or through your diet is actually pretty inert. To be actually useful to your body, it needs to be converted into this calcifediol.

The thing is that gram for gram – or microgram for microgram – Vitamin D3 produces more calcifediol than Vitamin D2 when they are metabolised by the body. This means that, although the actual effect of the two vitamins is the same, Vitamin D3 is more powerful in producing those effects.

According to clinical trials, D3 boosts calcifediol levels almost twice as much as D2, suggesting it is a much more active form of the vitamin.

Taking Vitamin D or D3 Supplements

In the UK, medical advice from the NHS recommends that adults should at least consider taking Vitamin D or D3 supplements throughout the winter months. This is because the British climate doesn’t offer enough sunshine from September through to March to maintain recommended Vitamin D levels (10mcg daily for adults) – and there are only limited food sources through which to receive the vitamin.

Supplements for Vitamin D and D3 are readily available from pharmacists and supermarkets – and, unless you are a vegan, it is probably best to go for the Vitamin D3 supplements.

However, dietary supplements aren’t always necessary or advisable. If you get enough sun exposure already, or eat a lot of oily fish, you shouldn’t need to take Vitamin D supplements at all. 10 micrograms a day is generally considered to be enough.

It is possible to have too much Vitamin D, and any more than 10 micrograms does run the risk of side effects. These can include vomiting, abdominal pain, confusion, and dehydration in serious cases of Vitamin D toxicity. 

Key Takeaways: Vitamin D vs D3

So, Vitamin D vs D3 – which should you take? That depends on your personal needs, lifestyle, and your dietary preferences. If you are looking for maximum results from a supplement, then Vitamin D3 is your best bet. However, if you are a vegan, D3 is not going to work for you – as it generally comes from animal products. In this case, Vitamin D2 supplements will do just fine.

Importantly, you should not be taking supplements of any vitamin if you do not need to. Deficiencies can be debilitating, but you can have too much of a good thing. So, if your lifestyle sees you outdoors regularly, you may not need supplements at all.


British Nutrition Foundation – New advice on vitamin D:


NHS – Vitamin D deficiency in children:


Cristina Palacios and Lilliana Gonzalez (2014). Is vitamin D deficiency a major global public health problem?:


R. Jorde M. Sneve Y. Figenschau J. Svartberg K. Waterloo (2008). Effects of vitamin D supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial:


Mitsuyoshi Urashima, Takaaki Segawa, Minoru Okazaki, Mana Kurihara, Yasuyuki Wada, Hiroyuki Ida (2010). Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren:


Giacomo Tirabassi, Maurizio Sudano, Gianmaria Salvio, Melissa Cutini, Giovanna Muscogiuri, Giovanni Corona, Giancarlo Balercia (2018). Vitamin D and Male Sexual Function: A Transversal and Longitudinal Study:


Laura Tripkovic, Helen Lambert, Kathryn Hart, Colin P Smith, Giselda Bucca, Simon Penson, Gemma Chope, Elina Hyppönen, Jacqueline Berry, Reinhold Vieth, Susan Lanham-New (2012). Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis:


Elisabetta Romagnoli, Maria Lucia Mascia, Cristiana Cipriani, Valeria Fassino, Franco Mazzei, Emilio D’Erasmo, Vincenzo Carnevale, Alfredo Scillitani, Salvatore Minisola (2008). Short and long-term variations in serum calciotropic hormones after a single very large dose of ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) in the elderly:


Ewa Marcinowska-Suchowierska, Małgorzata Kupisz-Urbańska, Jacek Łukaszkiewicz, Paweł Płudowski and Glenville Jones4 (2018). Vitamin D Toxicity–A Clinical Perspective:

While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

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