Fat-Soluble Vitamin
Vitamin D3 (Cholecalciferol)
Strong EvidenceRecommended Dose
2000–5000 IU daily (test blood levels first)
Timing
Morning with a fatty meal
Mechanism of Action
Binds to VDR receptors in the brain, modulating over 1,000 genes involved in neuroplasticity, immune regulation, and calcium signaling. Supports serotonin synthesis via TPH2 activation.
Side Effects & Safety
Safe at recommended doses. Toxicity possible above 10,000 IU/day chronically. May raise calcium levels — pair with K2 for safety. Test 25(OH)D levels.
Synergies
Omega-3Magnesium GlycinateVitamin K2