11 Essential Bone Health Facts About Calcium and Vitamin D You Should Know

3. Vitamin D3 versus D2: which one should you pick?

There are two main supplement forms: D3 (cholecalciferol) and D2 (ergocalciferol). D3 comes from animal sources and is the same form your skin makes after sun exposure. D2 is plant-derived and used in some fortified foods and prescriptions. Evidence shows that D3 often raises and keeps blood vitamin D levels higher than D2 when given in the same doses, so many clinicians prefer D3 for routine supplementation. That said, D2 remains useful and is sometimes used under medical guidance. If you follow a vegetarian or vegan lifestyle and prefer plant-based options, look for D2 or vegan-labeled D3 (made from lichen). When choosing a supplement, check the label for IU amount and whether it is D3 or D2. For general maintenance, small daily doses (as recommended by your clinician) are often easier to manage than occasional very large doses. Always match supplement choice to your dietary preferences and medical advice.