Vitamin D2 (ergocalciferol)
What it is
The plant-derived form of vitamin D, obtained from UV-irradiated mushrooms or yeast. Multiple trials show D2 is less effective than D3 at raising and maintaining blood vitamin D levels. The Tripkovic et al. 2012 AJCN meta-analysis (confirmed by Tripkovic 2017 RCT) found D3 raises 25-OH-D levels substantially more effectively than D2 at equivalent doses. The only advantage of D2 is that it is suitable for strict vegans. If vegan, consider vegan-sourced D3 from lichen as a better alternative.
Dose
1,000–2,000 IU/day; D3 is significantly more effective — use D2 only if vegan D3 is unavailable
Time of day & tips
Take with a fatty meal for best absorption. Once daily is sufficient. Vegan D3 from lichen is a better alternative if available.
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