02/11/2026
Vitamin D - built in 3 organs
Here’s the shortcut to how sunlight becomes a hormone in 7️⃣ steps:
1️⃣ Sunlight Sparks It
UVB converts 7-dehydrocholesterol in skin into Vitamin D₃.
💡 Low sun, sunscreen, darker skin → less D₃ formed.
2️⃣ Or You Eat It
Fatty fish, eggs, fortified foods, or supplements provide D₂/D₃.
💡 But it’s inactive when swallowed — still just “raw material.”
3️⃣ Liver Conversion Needs Magnesium
In the liver, enzymes (25-hydroxylase) turn D₃ → 25-hydroxy D (calcidiol).
💡 Magnesium is required here as a cofactor — low Mg = stalled activation.
4️⃣ Kidney Activation Needs Magnesium + Iron
In the kidney, 1α-hydroxylase turns calcidiol → calcitriol (active hormone).
💡 This step also needs magnesium. Iron supports enzyme activity, too.
5️⃣ Vitamin K2 Directs the Traffic
Active D increases calcium absorption, but K2 activates proteins (osteocalcin, MGP) that shuttle calcium into bone instead of arteries.
💡 D without K2 = calcium may end up in the wrong places.
6️⃣ Zinc + Vitamin A for the Receptor
Vitamin D works by binding to the Vitamin D Receptor (VDR), which needs zinc for structure and vitamin A (retinoic acid) for full function.
💡 Without these, signaling is weaker even if calcitriol is present.
7️⃣ The Payoff
Active vitamin D regulates calcium & phosphate balance, strengthens bones, helps the pancreas release insulin, and modulates immunity.
💡 But without magnesium, K2, zinc, and vitamin A, the chain breaks.
