Best Vitamin D3 for Immunity
Vitamin D3 is essential for immune regulation. Pairing with K2 (MK-7) improves calcium handling. We weight dosage and certifications highest.
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How we rank products
Every product receives an Overall Score (0–100) built from seven sub-scores: ingredient quality, bioavailability, dosage, clean label, certifications, user trust and value. For this page we re-weight those sub-scores for the Immunity use case, then apply ingredient bonuses and hard penalties (artificial fillers, proprietary blends, poor forms) before ranking. The full methodology is fully deterministic and re-runs whenever a product is edited.
Frequently asked questions
How much D3 per day?
1000–4000 IU per day is the most common range for adults.
Do I need K2 with D3?
K2 helps direct calcium to bones, complementing D3.