Vitamin D2 vs. Vitamin D3: Which One Is Right for You?
Medically Reviewed by Dr. Nicole Avena

Are you feeling the winter blues?

One nutrient that may help lift your spirits is vitamin D.

But wait, isn’t there also something called vitamin D3?

Indeed, there are two main forms of vitamin D: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). While they may seem similar, there are key differences between the two forms that affect how they function in our bodies.

Let’s dive deeper into these two types of vitamin D.

What Is Vitamin D?

Vitamin D is a vitamin that’s essential for maintaining overall health and well-being. It plays a crucial role in the body’s ability to absorb calcium, which is necessary for building strong bones and teeth. Vitamin D also is involved in supporting immune function, regulating mood, and promoting healthy cell growth.

Vitamin D is a fat-soluble vitamin that plays an important role in keeping our body healthy and functioning properly. It’s also referred to as the “sunshine vitamin” because our skin produces it when exposed to sunlight.

Once vitamin D has been absorbed into the bloodstream, it travels to the liver, where it gets converted into a form called 25-hydroxyvitamin D (calcidiol). This form then travels to the kidneys, where it’s further modified into its most active form known as 1,25-dihydroxyvitamin D (calcitriol). It’s this final form that carries out all the important functions of vitamin D in our body.

One of the main roles of vitamin D is promoting calcium absorption from our intestines, which helps maintain strong bones and teeth. In fact, without enough calcium intake, consuming more vitamin D doesn’t have any significant benefits for bone health.

What Is Vitamin D3?

Vitamin D3 (cholecalciferol) is produced by human skin cells when exposed to sunlight. When ultraviolet B radiation is absorbed by the skin, it triggers a reaction in cholesterol molecules that leads to the production of vitamin D3. This process typically occurs within 15-20 minutes of sun exposure on bare skin, making sunlight one of the primary sources of vitamin D3.

Once obtained through sunlight or consumed through food or supplements, vitamin D3 undergoes several metabolic steps before becoming an active form that can be used by the body.

While both vitamin D2 and D3 have similar functions in the body, research suggests that vitamin D3 may be more effective at increasing blood levels of vitamin D, and may have a longer duration of action, compared to vitamin D2. While both forms of vitamin D are essential for strong bones, teeth, and muscles, they have some key differences…

Vitamin D2 vs. Vitamin D3: 6 Key Differences!

  1. Sources

Vitamin D2 vs D3 2 One of the main differences between vitamin D2 and vitamin D3 is their sources. Vitamin D can be found in many plant sources, mushrooms, and fortified foods.

On the other hand, vitamin D3 is primarily obtained through sunlight exposure. It’s produced when UVB rays from the sun are absorbed by the skin cells.

Aside from sunlight exposure, small amounts of vitamin D3 can be found in select animal-based foods such as fatty fish (like salmon, tuna, and mackerel), liver, egg yolks, and beef. However, it’s worth noting that these food sources provide only a fraction of the recommended daily intake for vitamin D3.

  1. Absorption

Another significant difference between these two vitamins is their absorption rate by our body. Studies have shown that vitamin D3 has a higher bioavailability (better absorption into the body) than vitamin D2.

  1. Conversion

When it comes to converting into its active form in the body, there’s a notable difference between these two vitamins. While vitamin D2 needs to undergo conversion in both the liver and kidneys to become active, vitamin D3 only needs to convert once in the liver.

  1. Function

Both vitamin D2 and vitamin D3 are essential for maintaining bone health, but they have different functions in our body. Vitamin D2 is commonly used to fortify foods and supplements, while vitamin D3 is used primarily in our bodies to regulate calcium levels and strengthen bones.

  1. Dosage

The recommended daily intake of vitamin D varies according to leading health sources. The US Institute of Medicine’s daily allowance is 400-800 IU, but other commonly recommended dosages range from 1000-2000 IU. Due to its greater efficacy, it’s recommended to take vitamin D3 rather than D2.

  1. Deficiency

Deficiency of both vitamins can lead to similar conditions like soft bones in children and brittle bones in adults. However, studies have shown that supplementation with vitamin D3 can help support healthy blood levels of vitamin D more efficiently than vitamin D2.

The D3 Difference

Vitamin D3 is an essential micronutrient for overall health and well-being. It’s produced by our bodies in response to sunlight exposure and can be found in small amounts in certain foods. It undergoes several metabolic processes before becoming an active form that supports various bodily functions.

It’s crucial to meet the recommended daily intake of vitamin D3 through a balanced diet or supplements to maintain optimal health. Be sure to consult with a doctor or other healthcare practitioner before starting any supplement regimen.


At BrainMD, we’re dedicated to providing the highest purity nutrients to improve your physical health and overall well-being. For more information about our full list of brain healthy supplements, please visit us at BrainMD.

These statements have not been evaluated by the FDA. This content is for informational purposes only. It is not meant to substitute for medical or healthcare advice from a physician, nor is it intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before beginning a new health regimen.

Keith Rowe
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Barbara Stump

Other sources have cited that best absorption of D3 is found with liposomal K. there are so many differing opinions about vitamins it hard to know who has the correct info.