Differences between Vitamin D2 and Vitamin D3
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Vitamin D2 vs. Vitamin D3[edit]
Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol) are two forms of vitamin D. Both are converted in the body to the active form, calcitriol.[1] While both forms contribute to vitamin D levels, there are differences in their origin and how effectively they are utilized by the human body.[2][3]
Vitamin D2 is derived from plant and yeast sources, while vitamin D3 is produced by the skin upon exposure to sunlight and is also found in animal-based foods.[4][2] Studies suggest that vitamin D3 is more effective at raising and maintaining blood levels of vitamin D for longer periods compared to vitamin D2.[5][3]
Comparison Table[edit]
| Category | Vitamin D2 (Ergocalciferol) | Vitamin D3 (Cholecalciferol) |
|---|---|---|
| Primary Sources | Plant-based sources such as mushrooms (exposed to UV light), fortified foods (cereals, plant milks), and dietary supplements.[2] | Animal-based foods like fatty fish (salmon, mackerel), fish liver oils, egg yolks, and liver.[2] It is also synthesized in the skin when exposed to sunlight. A vegan form of D3 derived from lichen is also available. |
| Chemical Structure | The side chain of the molecule contains a double bond and an additional methyl group. | The side chain has a single bond structure. |
| Metabolism | Converted in the liver to 25-hydroxyvitamin D2.[2] This form has a lower binding affinity to vitamin D-binding protein. | Converted in the liver to 25-hydroxyvitamin D3.[2] This form binds more effectively to the vitamin D-binding protein, leading to a longer circulation time. |
| Bioavailability | Less effective at raising and maintaining serum 25(OH)D levels compared to D3.[5] | More effective in increasing and sustaining serum 25(OH)D levels.[5] |
| Half-life | Shorter half-life in the body. | Longer half-life, remaining in circulation for a greater duration. |
| Stability | May be more susceptible to degradation from humidity and temperature fluctuations.[2] | Generally considered more stable. |
Efficacy in Raising Vitamin D Levels[edit]
Multiple studies and meta-analyses have concluded that vitamin D3 is more potent than vitamin D2 in increasing the concentration of 25-hydroxyvitamin D [25(OH)D], the primary indicator of vitamin D status in the blood. Research indicates that vitamin D3 can be almost twice as effective as vitamin D2 at raising these levels.[2] This difference in efficacy is attributed to the way each form is metabolized and binds to the vitamin D-binding protein in the bloodstream. Vitamin D3's higher binding affinity allows it to persist in the body for a longer period.
While both forms are absorbed in the gut, the liver metabolizes them into different compounds.[2] Most steps in the metabolic pathway are the same for both D2 and D3. However, the structural differences in their side chains affect their binding to proteins and enzymes involved in metabolism.
Despite the differences in efficacy, both D2 and D3 are used in supplements and food fortification to prevent and treat vitamin D deficiency. Some research suggests the difference in raising vitamin D levels is more pronounced with large, infrequent doses, whereas the effect may be less distinct with daily supplementation. Factors such as body mass index may also influence the response to supplementation with either form.
