The Betterment Project

What Is The Difference Between Vitamin D2 and D3?

Vitamin D is one of the most common vitamin deficiencies in the world, and many people turn to vitamin D supplements in order to get their necessary share. It may be confusing then, as you browse through the pharmacy, when there are multiple varieties of vitamin D available. How are you supposed to know which one is better, and which one will best meet your needs?


This article will identify the differences between vitamin D (or vitamin D2) and vitamin D3. It will then explain which one is preferred, and how you can achieve optimal levels of vitamin D in the body. 


What Does Vitamin D Do?


Vitamin D is essential to the body’s wellbeing. Its main job is to maintain healthy levels of calcium and phosphate in the body. These minerals are responsible for building strong and durable bones, teeth, and muscles. Adequate levels of calcium and phosphate also help prevent muscle spasm and cramps, and allow for bone mineralization. 


Vitamin D also plays an important role in immune function. In fact, some studies are showing that vitamin D deficiency increases the risk for complications and more severe illness when fighting COVID-19. 


Finally, vitamin D can help ease irritation throughout the body, improve neuromuscular health, and maintain regular cell growth. 


Vitamin D deficiencies are extremely common. People that live farther away from the equator are at a higher risk for a vitamin D deficiency, due to limited sun exposure. Darker-skinned people are also more likely to be deficient in vitamin D. 


The three main sources of vitamin D are sunlight, food, and supplements.


When you are outdoors from around late March to the end of September, the sensation of direct sunlight on your skin can cause the body to produce vitamin D, which is why vitamin D is known as the sunshine vitamin. During times of limited sunshine, however, people may struggle to produce enough vitamin D on their own, and turn to food and supplements instead.


Foods such as oily fish (like herring, mackerel, salmon, and sardines), liver, egg yolks, and red meat are good sources of vitamin D. There are also many foods that can be fortified with vitamin D, such as orange juice and oat milk.


Lastly, vitamin D supplements are widely available and safe to use with the right dose. People with severe vitamin D deficiencies may use up to 5000 IU (international units) of vitamin D, while people with insufficient concentrations of vitamin D can consume around 2000 IU, and everyone else should take no more than 800 IU.


Vitamin D supplements are available in the D2 or D3 form.

What is Vitamin D2?


When we talk about vitamin D, we are usually referring to vitamin D2. Vitamin D2, or ergocalciferol, is derived from plant sources, one example of which is wild mushrooms. Vitamin D2 is less expensive to make than vitamin D3, so most fortified food sources of vitamin D contain the D2 form.


Vitamin D2 is commonly used, with a prescription, to treat hypoparathyroidism (decreased thyroid hormone secretion), hypophosphatemia (low concentrations of phosphorus in the body), vitamin D resistant rickets (soft and weak bones caused by low levels of phosphate), and vitamin D insufficiency.


Once inside the body, vitamin D2 is converted into 25-hydroxyvitamin D2, or calcifediol. In its active form, there is little to no difference between vitamin D2 and vitamin D3. 

What is Vitamin D3?


Vitamin D3, or cholecalciferol, is a form of vitamin D that is derived from animal sources, such as fish oil, liver, egg yolks, and fatty fish. Vitamin D3 is the type of vitamin D that the skin produces when it is exposed to sunlight.


All forms of vitamin D3 are available over-the-counter, so the FDA does not allow for any specific treatment claims to be made for vitamin D3 (or any OTC vitamins, for that matter). However, it is typically used for people with vitamin D deficiency.


Vitamin D3 is metabolized by the liver into 25-hydroxyvitamin D3, also known as calcifediol. As previously mentioned, once in this form, there is no real distinction between vitamin D2 and vitamin D3. 

Which is Better: Vitamin D2 or Vitamin D3?


When you take a vitamin D supplement, either D2 or D3, it will first be absorbed in the small intestine. Vitamin D2 and D3 are both fat-soluble vitamins, meaning they are stored in the body’s tissues until needed (rather than being used right away). As a result, there is no difference in the way either vitamin is dissolved, stored, or absorbed. 


Similarly, vitamins D2 and D3 are both metabolized by the liver into calcifediol, the active form of vitamin D in the body. Once they are metabolized in the body, these two forms of vitamin D are used for the same things: calcium absorption, immune health, phosphate regulation, etc. When a doctor runs labs to test vitamin D levels, they are really checking for calcifediol, and cannot distinguish between the amount of D2 and D3 that compose these calcifediol levels.


As such, this means that vitamins D2 and D3 are metabolized the same way and perform the same roles in the body. So, the main difference is in how well they can raise calcifediol levels. 


Multiple studies show that vitamin D3 is more effective in increasing the amount of calcifediol in the body. 


One study, whose participants were post-menopausal, vitamin D-deficient women, showed that vitamin D3 is about double as effective as vitamin D2 in raising calcifediol levels. Another study, performed this time on adults that were matched for age, body mass index (BMI), and race/ethnicity, also tested which of vitamin D2 or D3 could increase calcifediol concentrations more efficiently, and also came up with the results that D3 was more effective. 


Vitamin D3 has also been shown to increase energy levels in those suffering from severe vitamin D deficiencies. A study whose participants were experiencing extreme fatigue as a result of their vitamin D deficiencies demonstrated that vitamin D3 supplementation can help alleviate symptoms. 

The Right Vitamin D Supplement For You


Now that you know vitamin D3 is the more efficient vitamin D supplement available, it can still be hard to choose which dose and brand is best for you. 


ASYSTEM Superhuman Supplements, in addition to vitamin D, provides the body with all the clinically-proven vitamins, minerals, and natural compounds it needs to perform at its best. Just take your convenient daily pack of five pills (featuring optimal dosages and award-winning, patented ingredients), and achieve sustained energy, a stronger immune system, better focus, deeper sleep, less stress, and improved mental health. 


Learn more about ASYSTEM Superhuman Supplements here

In Summary


Vitamin D2 and D3 are used to build stronger bones and support better immune and neuromuscular function. Once inside the body, these vitamins perform the same tasks and are metabolized and stored in the same way. Vitamin D3 supplements, however, have been shown to be more effective in increasing the body’s vitamin D levels than vitamin D2 supplements. 


Using ASYSTEM Superhuman Supplements is a great way to not only avoid/remedy vitamin D deficiency, but also to optimize your energy, enhance your immune system, and unlock your potential. 


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