Does It Matter If I Take Vitamin D or D3? Understanding the Differences

December 9, 2025 •

4 min read

An estimated one billion people globally have a vitamin D deficiency, a common nutritional shortfall with widespread health implications. While often discussed as a single nutrient, vitamin D actually exists in two primary forms: vitamin D2 and D3. For many consumers, this raises the important question of whether the specific form of their supplement truly matters.

Quick Summary

Vitamin D is a collective term for both D2 and D3. These forms differ in their sources and potency, with D3 generally considered more effective at raising and maintaining blood levels.

Key Points

Source Differences: Vitamin D2 comes from plant-based sources like fortified foods and mushrooms, while Vitamin D3 is produced in the skin from sunlight and found in animal products.
D3 is More Potent: Research shows Vitamin D3 is significantly more effective at raising and sustaining blood vitamin D levels than D2.
Dietary Considerations: Vegans typically opt for D2 or vegan-sourced D3 (from lichen), whereas D3 derived from lanolin is suitable for omnivores.
Absorption: Both D2 and D3 are well-absorbed, particularly when taken with a meal containing some fat.
Overall Function: Both forms serve the same function once converted in the body, but D3 has a more powerful biological impact.
Consult a Professional: It is best to consult with a healthcare provider to determine the right form and dosage for your needs.

What is Vitamin D?

Vitamin D is a fat-soluble vitamin that plays a critical role in numerous bodily functions. It's most famously known for aiding in calcium absorption, which is essential for developing and maintaining strong bones. However, its benefits extend to immune system support, muscle function, and even mood regulation. While some foods are fortified with vitamin D, the body's primary source is sunlight exposure, which triggers production in the skin.

There are two main forms of this crucial nutrient that you will encounter in foods and supplements:

Vitamin D2 (Ergocalciferol): This is the plant-based form, primarily found in fungi and yeasts exposed to UV light. It is often used to fortify foods like cereals, plant-based milks, and juices.
Vitamin D3 (Cholecalciferol): This is the form produced by the body in response to sunlight on the skin. It is also found in animal-based foods, such as fatty fish, egg yolks, and liver. A vegan-friendly version derived from lichen is also available.

The Key Differences: D2 vs. D3

While both forms of vitamin D eventually undergo a two-step conversion in the liver and kidneys to become the active hormone calcitriol, their journey and overall effectiveness differ.

Sources and Absorption

Sources: The most obvious difference lies in their origins. D2 is for those who rely on plant-based sources or fortified foods, including vegans and vegetarians. D3 comes from animal products and is the form your body naturally produces from sun exposure.
Absorption: Both are well-absorbed in the gut, especially when taken with a meal containing some fat. However, the real difference emerges in the body's metabolism and utilization of the vitamins.

Potency and Effectiveness

Scientific research consistently points to vitamin D3 being more potent and effective at raising and maintaining the body's overall vitamin D levels (measured as 25-hydroxyvitamin D). A significant study showed that D3 was approximately 87% more effective at raising serum concentrations than an equimolar dose of D2.

Reasons for D3's Superiority:

Longer Half-Life: Vitamin D3 has a longer shelf-life and a longer duration of action in the body compared to D2, meaning its effects last longer.
Greater Storage: Research indicates that D3 leads to significantly greater storage of vitamin D in the body's fat reserves than D2, which helps sustain levels over time.
Higher Calcifediol Levels: The liver metabolizes both D2 and D3 into calcifediol, the main circulating form of vitamin D. However, studies repeatedly show that D3 generates higher levels of calcifediol than D2.

Should You Choose D3 Over D2?

For most people, especially those who consume animal products, vitamin D3 is the preferred option due to its superior effectiveness at boosting and sustaining vitamin D levels. However, the choice is not always clear-cut and depends on several factors.

For example, those following a strict vegan diet who do not wish to consume animal-derived supplements should opt for vitamin D2 or a vegan-sourced D3 (from lichen). In cases of severe deficiency, a healthcare provider may prescribe high-dose D2, but for general supplementation, D3 is the more commonly recommended choice. For individuals who are overweight or obese, some studies suggest the potency difference between D2 and D3 may be less pronounced, as excess body fat can blunt D3's advantage. Always consult a healthcare professional to determine the right form and dosage for your individual needs.

Comparison Table: Vitamin D2 vs. Vitamin D3


Feature	Vitamin D2 (Ergocalciferol)	Vitamin D3 (Cholecalciferol)
Primary Source	Plant-based sources, fungi, yeast, fortified foods	Sunlight exposure on skin, animal products (fatty fish, eggs), lichen-based vegan options
Natural Occurrence	Produced in plants and fungi exposed to UV light	Produced in animal and human skin when exposed to sunlight
Potency	Less potent at raising blood vitamin D levels	More potent and effective at raising blood vitamin D levels
Effectiveness	Increases vitamin D levels, but not as efficiently as D3	Increases vitamin D levels higher and for a longer duration
Vegan Friendly	Yes, inherently plant-based	Yes, if derived from lichen; typically animal-based (lanolin)
Over-the-Counter	Available in various strengths	Widely available in many strengths
Prescription	High-dose formulations (e.g., 50,000 IU) are often prescription-only	Generally available over-the-counter

Conclusion: Which One Should You Take?

Ultimately, the choice between vitamin D and D3 depends on your specific dietary needs and individual health factors. For most people seeking to maximize their vitamin D levels through supplementation, the consensus points toward vitamin D3 due to its higher potency and superior ability to be utilized by the body. It is more effective at raising serum levels and maintaining them over a longer period. However, for vegans and vegetarians, D2 is a viable option, and vegan-sourced D3 is also widely available. Regardless of your choice, the most important step is ensuring you receive an adequate intake of vitamin D, as chronic deficiency is a serious public health concern. Always consult with a healthcare professional to determine the most suitable form and dosage for your unique circumstances and to monitor your vitamin D status. The NIH Office of Dietary Supplements provides additional facts for consumers regarding vitamin D.

Frequently Asked Questions

No, 'vitamin D' is a general term that encompasses two main forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Both are members of the vitamin D family, but they are not the same molecule.

Scientific studies consistently indicate that vitamin D3 is more effective than vitamin D2 at increasing and sustaining blood levels of vitamin D in the body.

Vitamin D2 is primarily sourced from plants and fungi, such as mushrooms, particularly when they are exposed to UV light. It is also commonly found in fortified foods like cereals, orange juice, and plant-based milks.

Vitamin D3 is produced by the human body and animals when their skin is exposed to sunlight. Dietary sources include animal products like fatty fish (salmon, tuna), egg yolks, and beef liver. Vegan-friendly D3 is also derived from lichen.

Yes, vegans can get enough vitamin D. They can choose supplements containing vitamin D2, which is always plant-based, or look for specific brands of D3 that are sourced from lichen. Fortified foods are also an important source.

Both D2 and D3 are converted in the liver and kidneys to become the active hormone calcitriol. The key difference is that D3 is more efficiently converted and utilized, resulting in higher and more sustained blood levels.

While both forms support bone health by aiding calcium absorption, D3 is generally considered superior due to its higher potency and greater impact on maintaining blood vitamin D levels over time.

For many, especially during winter months, sun exposure alone is not sufficient to maintain adequate vitamin D levels. People with darker skin tones, limited sun exposure, or certain medical conditions may benefit from supplementation with D3.