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Vitamin D2 vs D3: What's the difference?

Family walking on hills near a lake with the sun shining
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We all know a healthy lifestyle incorporates a balanced and nutritious diet, exercise, and plenty of vitamin D. During the spring, summer, and early autumn we should be able to get all the vitamin D we need from sunlight. Outside of these months, the NHS recommends taking supplements.

If you’ve recently shopped for vitamin D supplements you might have noticed that some products are labelled as containing “vitamin D2” or “vitamin D3”. The reason for this is that there are two different varieties of vitamin D which come from different sources but work in very similar ways.

To learn more about the difference, and for some tips on topping up your vitamin D, read on.  

What is vitamin D?

Vitamin D is an essential nutrient found in some of the food we eat. Our bodies can also generate vitamin D through sun exposure.

We need vitamin D because it helps to keep the bones, muscles, and teeth healthy by regulating levels of calcium and phosphate in the body. Not getting enough vitamin D can cause problems with the bones.

In the autumn and winter when UV light in the UK isn’t very strong, we need to eat foods rich in vitamin D. The NHS also recommends taking 10 micrograms (mcg) of vitamin D supplements each day.

Vitamin D3 comes from animals, vitamin D2 from plants

As we’ve talked about, there are two main types of vitamin D:

  • Vitamin D2
  • Vitamin D3

Vitamin D2 is known as ergocalciferol and is found in plants and fungi e.g. mushrooms. Plants can generate vitamin D2 through exposure to UV light. If you’re vegan, look for supplements that contain vitamin D2 as these will be sourced from plants rather than animal products.

You can learn more about supplements suitable for vegans by reading our blog.

Vitamin D3 is known as cholecalciferol and is found in animals and animal products, including oily fish like salmon and mackerel. This is also the type of vitamin D that our bodies generate through sun exposure. If you eat animal products, you can buy supplements that contain vitamin D3.

Vitamin D3 is formed in your skin

When UV light hits the skin it acts on a compound called 7-dehydrocholesterol, converting it into vitamin D – and more specifically, vitamin D3.

It’s not clear exactly how much time we need to spend in the sun to get adequate vitamin D, however we do know the following:

As a rough guide, the British Skin Foundation recommends “daily sunlight exposure” of 10 to 15 minutes for people with lighter skin, and 25 to 40 minutes for people with darker skin.

Just make sure that when you’re spending time outside you’re doing it safely, by:

  • Spending time in the shade during the hottest part of the day (11am-3pm)
  • Using sunscreen with an SPF of at least 30 and a UVA star rating of at least four
  • Making sure you don’t burn

Read our sun safety blog for more advice. 

Vitamin D3 is more effective at improving vitamin D status

Supplements containing vitamin D3 are thought to be more effective than those containing vitamin D2, so if you have the option of choosing between the two, it’s best to go for vitamin D3. If you’re vegan, you’ll want to stick to vitamin D2.

How to improve your vitamin D status

It’s thought that lots of people who live in northern latitudes, including the UK, are deficient in vitamin D, because of the lack of sun during the autumn and winter. For this reason, the NHS recommends that everybody takes a vitamin D supplement of 10 micrograms (mcg) each day between October and March.

If you have dark skin, spend most of your time inside, or cover most of your skin when you go outside, you may want to consider taking vitamin D supplements year-round.

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You can also supplement your vitamin D status by eating one or two portions of oily fish each week, as this is the best source of dietary vitamin D. If you don’t eat animal products, wild mushrooms and foods fortified with vitamin D (e.g. cereals) are a good alternative. Find out more by reading about the sources of vitamin D.