Author: Vicky Godfrey (Nutritional therapist) CNM, BANT, CHNC, ANP.

Key Differences Between Vitamin D2 and D3

• Vitamin D2: Less effective at raising and maintaining blood Vitamin D levels, and high doses are more likely to lead to adverse effects due to its metabolic pathway.
• Vitamin D3: More effective and safer for human supplementation, with a better conversion rate to the active form (calcitriol) in the body.

Should You Avoid Vitamin D2?

While Vitamin D2 has been used medically to treat deficiencies, it’s less bioavailable and efficient than Vitamin D3. For supplementation, Vitamin D3 (cholecalciferol) is the better choice for both safety and effectiveness.

If you’re concerned about Vitamin D and its effects on your body, genetic testing (like with DNApal) can provide personalised insights to help you choose the right form and dose for your needs.

In general, Vitamin D2 (ergocalciferol) is not the preferred choice for supplementation, and here’s why:

Why D2 Isn’t Ideal as a Supplement

1. Lower Potency
   Vitamin D2 is less effective at raising and maintaining Vitamin D levels in the blood compared to D3. Studies show that D2 is metabolized more quickly, which can make it harder to achieve and sustain optimal levels.
2. Stability Issues
   D2 is less stable than D3, meaning it degrades faster over time, especially when exposed to heat or light. This can reduce its effectiveness in supplements.
3. Different Metabolic Pathway
   The way D2 is processed in the body can lead to less efficient conversion into calcitriol, the active form of Vitamin D that the body uses.
4. Increased Risk of Toxicity
   Although uncommon, high doses of D2 are more likely to cause issues like hypercalcemia (too much calcium in the blood) compared to D3. This is partly why it’s used in rodenticides—when given in extremely high doses, it disrupts calcium regulation.
5. Less Natural Source
   Vitamin D2 is derived from plants and fungi, such as UV-exposed mushrooms. While it’s suitable for vegetarians and vegans, it’s not as bioidentical to the form produced in human skin (D3), making it less effective in supplementation.

When Is D2 Used?

Despite its limitations, Vitamin D2 may still be prescribed in specific cases, such as:

• For vegetarians or vegans who avoid animal-derived products.
• As a prescription form in certain countries, where D2 is more commonly used than D3.
• For short-term treatment of severe deficiency, though many experts now recommend D3 even in these cases.

Why D3 Is the Better Choice

Vitamin D3 (cholecalciferol) is the preferred supplement for most people because:

• It is more effective at raising and maintaining blood Vitamin D levels.
• It is bioidentical to the form your body naturally produces from sunlight.
• It has greater stability, making it more reliable in supplements.
• It is widely available and affordable, including vegan options derived from lichen.

Bottom Line

Unless you have a specific reason to take Vitamin D2 (such as dietary restrictions), it’s better to choose Vitamin D3 for supplementation. If you’re vegan, look for D3 derived from lichen, which offers the same benefits as animal-based D3 without the drawbacks of D2.

For a personalised approach, genetic testing (e.g., analysing your VDR and GC genes) and regular Vitamin D level monitoring can help you determine the best type and dose for your individual needs.  That’s what we do at DNApal.me – we give you personalised health advice just for you!

Why the Comparison?

• Rat Poison and Vitamin D2: Certain rodenticides (rat poisons) use high doses of Vitamin D2 to kill rodents. These poisons work by causing severe hypercalcemia (excess calcium in the blood), leading to calcification of soft tissues, kidney failure, and death in rodents.
• Human Use: In humans, Vitamin D2 is not toxic in the low doses typically found in supplements or fortified foods. However, its potency and stability are lower than Vitamin D3, which is why D3 is generally preferred for supplementation.