Vitamin D + K2 + Magnesium: Real Cofactor, Sold as a Synergy Stack

Summary

The "take D3 with K2 and magnesium" cofactor stack is one solid mechanism, one mixed clinical claim, and a layer of premium-bundle marketing: magnesium genuinely is an enzymatic cofactor for vitamin D metabolism (real Tier-1 biology) but only meaningfully shifts vitamin D status in people who are **magnesium-deficient**; K2 (MK-7) modestly **slows** coronary calcium **progression** in higher-risk groups (Tier 2–3, mixed) but does **not** unclog or reverse existing plaque; and the bundled "synergy stack" sold to healthy, well-fed adults is largely upsell, because vitamin K deficiency is rare on