Vitamin A (Retinol) vs Vitamin K2 (MK-7)

Mechanism

Retinol is converted to retinal (for vision, rhodopsin cycle in rod photoreceptors) and retinoic acid (for gene regulation). Retinoic acid binds RAR/RXR nuclear receptors, regulating >500 genes involved in cell differentiation, immune function, and embryonic development. It is essential for mucosal barrier integrity (gut, respiratory, skin epithelial cell turnover), T-cell differentiation (promotes Treg and Th2 over Th1/Th17), IgA secretion, and natural killer cell function. Works synergistically with Vitamin D — both share the RXR receptor as a heterodimer partner.

Standard Dosing

5000-10,000 IU retinol (1500-3000 mcg RAE) daily

Timing

With fat-containing meal. Best with vitamins D and K for synergistic fat-soluble vitamin balance.

Cycle Duration

ongoing

Side Effects

• Headache (chronic high dose)
• Dry skin/lips
• Hepatotoxicity (chronic excess)
• Hypercalcemia
• Hair loss (toxicity)
• Teratogenicity

Contraindications

• Pregnancy (>10,000 IU/day is teratogenic)
• Liver disease (hepatic storage and toxicity)
• Hypervitaminosis A
• Concurrent retinoid medication use

Best Stacking Partners

Mechanism

Vitamin K2 (menaquinone-7) activates vitamin K-dependent proteins via gamma-carboxylation of glutamic acid residues. Key targets: osteocalcin (directs calcium into bone matrix), matrix Gla protein (MGP, inhibits arterial calcification), Gas6 (cell signaling, neuroprotection), and protein S (anticoagulant). MK-7 has a long half-life (~72 hours vs 1-2 hours for K1) enabling consistent carboxylation activity with once-daily dosing. It works synergistically with Vitamin D3 to regulate calcium metabolism — D3 increases calcium absorption while K2 directs its deposition.

Standard Dosing

100-200 mcg MK-7 daily

Timing

With fat-containing meal alongside Vitamin D3.

Cycle Duration

ongoing (mandatory co-supplement with Vitamin D3)

Side Effects

• Generally very well tolerated
• Rare: mild GI discomfort
• Theoretical thrombotic risk in deficiency-rebound scenario (unproven)

Contraindications

• Warfarin/coumarin anticoagulant therapy (unless specifically directed by physician with INR monitoring)

Best Stacking Partners