Vitamin D: Which do I take? D2, D3, DK2?

Vitamin D, the vitamin we can’t seem to get enough of. You constantly hear someone saying “make sure you take your Vitamin D!”. It’s arguably one of the harder vitamins to maintain, but only usually for those of us in colder regions with less sunlight. There are tons of different Vitamin D supplements on the market so let’s break them down.

What does Vitamin D do?

Vitamin D is a fat soluble (meaning it is stored in our fat cells) vitamin that has a whole host of important functions in the body. Vitamin D is a key player in absorbing calcium for bone strength, as well as, other important electrolytes. It also plays a key role in our immune function and can even help with cancer prevention.

There are 2 distinct types of Vitamin D:

  • Vitamin D2
  • Vitamin D3

Vitamin D2 vs D3

Vitamin D2 is called Ergocalciferol. It differs from Vitamin D3 slightly in its chemistry, which is what earns it a different name. Essentially it has the same function of D3. Though they are similar, Vitamin D2 has been found to be more poorly absorbed than Vitamin D3. So if you’re going to choose one, go with Vitamin D3.

What is Vitamin DK2?

Vitamin DK2 is just Vitamin D and Vitamin K2 in the same supplement. Vitamin K2 is a completely separate vitamin, also called menaquinones. Vitamin K2 is a component of Vitamin K, which aids in clotting in the blood. K2 is thought to help promote bone health. There is too little evidence to support that adding K2 is doing anything more to enhance bone health so if it comes down to price point, then Vitamin D3 would work just fine. Most of us do not need to supplement Vitamin K in any form.


It’s important to remember that you shouldn’t be taking unnecessary vitamins unless you need to. When you see your doctor next, have them run a blood panel and check for Vitamin D levels, otherwise I wouldn’t recommend taking a fat soluble vitamin if you don’t need to.

I know we live in a culture obsessed with supplements, but taking too many can be taxing on the body and completely useless. If you don’t have a doctor or are questioning if you should take something, always ask a Registered Dietitian.

How much should I take?

This depends on your Vitamin D level status. If you are low and live in an area where the sun is hiding for half the year, I would say about 10,000 IU’s a day. If you’re low, but in an area where you can get 10-15 minutes of sun exposure a day, then I would say about 5,000 IU’s a day.


hi there, i’m michelle

welcome to my little home on the internet! I'm a Registered Dietitian and am here to share with you evidenced based and realistic ways to better your health for the long haul. Here you'll learn ways to eat that are both practical and sustainable. Enjoy!

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Current Location

New Hampshire

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