Vitamin D3: how much to take, and is 5000 IU too much?

How much vitamin D do you need?

Between about October and March, the sunlight in the UK is too weak for your skin to make vitamin D, whatever the weather does. That is why the advice is seasonal. The NHS suggests adults and children over one consider 10 micrograms a day through those months. Some groups are advised to take it all year: people who are rarely outside, who cover their skin, or who have darker skin and make less vitamin D from the sun. Pregnant and breastfeeding women are advised to take 10 micrograms a day throughout, which we cover in the pregnancy guide.

Ten micrograms is 400 IU. Both units mean the same thing, which is one of the reasons vitamin D confuses people.

D3 versus D2, and why lichen

Vitamin D comes in two forms. D2 comes from plants and fungi. D3 is the form your own skin makes and, on balance, the form that raises and holds blood levels more reliably. Most D3 is made from sheep's wool, which is a problem if you are vegan. Ours is D3 grown from wild-harvested lichen, a rare plant source of true D3, so you get the more reliable form without an animal ingredient. It is a sourcing detail to check on any vitamin D product you buy.

The dose ladder, and the 5000 IU question

Labels tend to be vague about dose, so here are the numbers that matter.

Whether 5000 IU is too much depends on the person and the reason for taking it. It sits just above the everyday upper level the UK sets, which is why we label it as high dose and why it suits someone who knows they run low, or who has been advised to take more, rather than someone just starting out. If you have never had your vitamin D level checked and you simply want cover through winter, 1000 to 2500 IU is the more sensible place to start. Vitamin D is fat-soluble, so unlike vitamin C your body stores it, and taking more than you need brings no extra benefit.

Vitamin D and K2

You will often see D3 sold with K2. The reasoning is that vitamin D helps your body absorb calcium, and vitamin K2 plays a part in how bone uses it, so the two are paired for bone support. If bones are your main reason for taking vitamin D, a D3 and K2 combination is a reasonable pick.

Which one should you choose?

For most people through winter, our 2500 IU lichen D3 is an easy, comfortable dose. If you know you run low or you have been told to take more, the 5000 IU is there as the high-dose option. If bone support is the goal, the D3 and K2 combination makes sense. All three are D3 from lichen, so they suit vegans.