Head-to-Head Comparison
Vitamin D2 vs Vitamin D3
VS
1 ties
Efficacy & Potency
★ 87% more potent at raising 25(OH)D levels.
Potency
Significantly less potent per IU.
★ Longer half-life — maintains levels better.
Duration of Effect
Shorter half-life — levels drop faster.
★ Stronger binding to vitamin D binding protein.
Binding Affinity
Weaker binding — cleared from blood faster.
★ More stable metabolites.
Metabolic Stability
Less stable — degrades faster during storage.
Sources & Suitability
Animal-derived (lanolin from sheep wool, or fish liver oil).
Natural Source
Plant/fungal-derived (UV-irradiated mushrooms or yeast). ★
Vegan D3 from lichen is available.
Vegan Options
Naturally vegan. ★
★ Widely available in all supplement stores.
Availability
Less common — mostly in prescription forms.
Very affordable.
Cost
Similar cost.
Our Verdict
Vitamin D3 is clearly superior to D2 for raising and maintaining blood levels of 25(OH)D. D3 is 87% more potent at raising vitamin D levels and maintains those levels for longer. The only advantage of D2 is that it's plant-derived (from fungi/yeast), making it suitable for strict vegans. However, vegan D3 from lichen is now widely available, making D2 largely obsolete.