From the Guidelines
Vitamin D3 is the preferred form of vitamin D supplementation due to its greater effectiveness in raising and maintaining blood levels of vitamin D compared to vitamin D2. The key difference between vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol) lies in their metabolism and ability to raise serum 25-hydroxyvitamin D [25(OH)D] levels, with vitamin D3 being more effective in this regard, especially when used in longer dosing intervals 1.
Key Differences
- Vitamin D3 is naturally produced in human skin upon sunlight exposure and is found in animal-based foods, whereas vitamin D2 is derived from plant sources and produced through UV radiation exposure of ergosterol from yeast and fungi.
- Vitamin D3 binds more efficiently to vitamin D-binding proteins in the bloodstream and is converted more readily to the active form, calcitriol, which is crucial for calcium absorption and bone health.
- The effectiveness of vitamin D3 over vitamin D2 is notable when considering supplementation regimens, such as the recommendation for patients with serum 25(OH)D levels below 30 ng/mL to take prescription vitamin D (ergocalciferol) 50,000 IU weekly for 8 weeks, followed by a recheck of the serum 25(OH)D level 1.
Supplementation Guidelines
- For adults, especially those over 50, a daily intake of 800 to 1000 IU of vitamin D, along with 1200 mg of calcium, is recommended by current expert opinion, with the understanding that many patients may require more than these recommended amounts based on their serum 25(OH)D levels 1.
- When choosing a supplement, vitamin D3 is preferred due to its superior efficacy in maintaining adequate vitamin D levels, with typical doses ranging from 600-2000 IU daily for adults, though individual needs can vary based on factors like age, sun exposure, and existing vitamin D levels.
From the Research
Difference between Vitamin D3 and D2
- Vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol) are two forms of vitamin D used to treat deficiency 2.
- Studies have shown that vitamin D3 is more effective in increasing serum 25-hydroxyvitamin D levels than vitamin D2 3, 4, 5.
- Vitamin D3 has a longer plasma half-life and higher affinity for the vitamin D binding protein, hepatic vitamin D hydroxylase, and vitamin D receptor compared to vitamin D2 2.
Efficacy of Vitamin D3 and D2 Supplementation
- A systematic review and meta-analysis found that vitamin D3 supplementation had a significant and positive effect on raising serum 25-hydroxyvitamin D concentrations compared to vitamin D2 4.
- A study comparing the effects of high-dose vitamin D2 and D3 on total and free 25-hydroxyvitamin D found that D3 increased total and free 25D levels to a greater extent than D2 5.
- Another study found that vitamin D3 injection alone or with a D2 tablet increased serum vitamin D levels more than vitamin D2 injection alone 3.
Implications for Treatment
- The findings suggest that vitamin D3 may be a preferred choice for supplementation, particularly for individuals with severe vitamin D deficiency 3, 4.
- However, more research is needed to examine the metabolic pathways involved in oral and intramuscular administration of vitamin D and the effects across age, sex, and ethnicity 4.