Vitamin D3 vs Vitamin D2 - What’s the Difference?


Bluebird Botanicals Vitamin D2 And D3 What's The Difference

In case you missed it, Bluebird launched a brand new and very exciting product last week - our Immune Support† Vitamin D3 + CBD Oil!

In a recent blog, we discussed the special features of our star ingredient, vitamin D3, and why it plays such an important role in our new CBD blend. But did you know that there are actually two different forms of this essential vitamin?

Today, we’re going to take a look at the differences between vitamin D3 vs D2 as well as why we chose to feature D3 in our new product.


Vitamin D3 vs Vitamin D2

Vitamin D3, also known as cholecalciferol, is a fat-soluble vitamin and an important nutrient for maintaining a healthy lifestyle. It’s most commonly derived from exposure to UVB rays from sunlight which converts cutaneous 7-dehydrocholesterol to pre-vitamin D3 and in turn, becomes the active form 25-hydroxy-vitamin D, abbreviated as 25(OH)D. It’s also found in some foods like fatty fish, egg yolks, and fortified dairy - but for the most part, is difficult to obtain through one’s diet alone.

Vitamin D2, known as ergocalciferol, is similar in form yet different in chemistry from its D3 counterpart. This vitamin is primarily derived from plants and fungi, particularly mushrooms who also convert it from the UVB rays of sunlight. You can obtain some vitamin D2 from eating mushrooms but otherwise, it’s not available for absorption from food sources.

The liver metabolizes vitamin D2 into 25-hydroxyvitamin D2 and vitamin D3 into 25-hydroxyvitamin D3. These two compounds are collectively known as calcifediol. Calcifediol is the main circulating form of vitamin D, and its blood levels reflect your body’s stores of this nutrient.

Why Vitamin D3?

Studies have made clear findings that vitamin D3 appears to have advantageous qualities that allow it to sustain its influence for longer and at greater concentrations than vitamin D2. This is in part because vitamin D2 has an extra methyl group, meaning that when it is synthesized into serum 25(OH)D, there is an extra step needed that vitamin D3 does not have to go through. This extra methyl group also allows vitamin D2 to be degraded more often as it is a weaker molecule than vitamin D3. 

There have been reports that this difference directly affects the rate of vitamin D2 conversion to serum 25(OH)D and also its affinity for the vitamin D binding protein, which are critical steps involved in the activation of vitamin D. Thus, this gives a vast advantage and potential for vitamin D3 to remain active, which strengthens the case for using D3 compared with D2 in our supplement.

How to get the vitamin D your body needs

Since sunscreen inhibits the body’s ability to convert sunlight into vitamin D and it’s not easy to obtain solely through your diet, how are you supposed to ensure you’re receiving enough?

The simplest answer is through supplements. There is a wide variety of both vitamin D2 and D3 supplement products available on the market today, and you may find it overwhelming to find the best one to suit your needs. Many first-timers struggle to pick a brand due to uncertainty about what is a safe or appropriate amount of vitamin D to take. 

The subject of Vitamin D3 serving safety has been fiercely debated in the literature, but based on current science, 2,500 IU per serving is Generally Regarded as Safe (GRAS) for adults over the age of 18. You will find many examples of Vitamin D3 supplements containing levels between 400 IU and 10,000 IU per serving. 

Good news - you can get the vitamin D3 your body needs right here! Bluebird’s newest Immune Support† blend features 2,500 IU of vitamin D3 alongside 4.2 mg of CBD to meet your wellness needs. 

Have questions? We’re here to help! You can reach out to our customer care team at or give us a call at 720-726-5132.