Vitamin D does way more than you think — and most people don't have enough. Dr. Lewis and Becca break down the science connecting vitamin D to pain, joint health, immunity, and autoimmune disease. Plus: injectable vitamin D, the Harvard VITAL trial, and why "normal" lab ranges aren't good enough.

KEY SOURCES

1. Wu Z, et al. Vitamin D concentration and pain: systematic review and meta-analysis (81 studies, 50,000+ participants). Public Health Nutr. 2018. https://doi.org/10.1017/S1368980018000551
2. Hahn J, et al. Vitamin D and omega-3 supplementation and incident autoimmune disease: VITAL randomized controlled trial (25,871 participants). BMJ. 2022.