Evidence-based health answers you can trust. Reclaim your health and change your life.

In this episode of Revolution Health Radio, Chris Kresser explains why vitamin D supplementation should never be one-size-fits-all. Drawing on new research—including a groundbreaking study on magnesium’s regulatory role—Chris explores how genetics, ethnicity, body weight, age, health status, sun exposure, and nutrient cofactors all shape an individual’s vitamin D needs. He outlines optimal testing strategies, safe and effective target ranges, and the critical roles of magnesium, vitamin K2, and vitamin A in vitamin D metabolism. The episode reframes vitamin D optimization as a personalized, systems-based approach that prioritizes balance, testing, and real-world physiology over generic dosing guidelines.