# item.guide
Side-by-Side Comparison Essential Vitamins & Minerals

Vitamin D3 (Cholecalciferol) vs. Vitamin K1 (Phylloquinone)

Comparing 2 standards across 10 specifications. 10 key differences identified.

Comparing:
Vitamin D3 (Cholecalciferol)
Vitamin K1 (Phylloquinone)
Vitamin D3 (Cholecalciferol) →

Vitamin D3 is a secosteroid prohormone synthesized endogenously in skin via solar UVB irradiation of 7-dehydrocholesterol. Adult RDA is 600–800 IU (15–20µg), with a Tolerable Upper Limit of 4,000 IU (100µg)/day, regulating systemic calcium absorption and immune gene expression.

View full Vitamin D3 (Cholecalciferol) spec sheet →
Vitamin K1 (Phylloquinone) →

Vitamin K1 is a fat-soluble naphthoquinone synthesized by photosynthetic plants. Adequate Intake (AI) is 120µg (men) / 90µg (women), acting as an essential cofactor for gamma-glutamyl carboxylase in blood clotting and osteocalcin bone mineralization.

View full Vitamin K1 (Phylloquinone) spec sheet →

Specification Comparison Table

10 Parameters
Parameter / Spec
Vitamin D3 (Cholecalciferol)
Vitamin K1 (Phylloquinone)
Nutrient Type
Fat-Soluble Secosteroid Prohormone Fat-Soluble Naphthoquinone Vitamin
Tolerable Upper Limit (UL)
4,000 IU / day (100 µg) (Endocrine Society: up to 10,000 IU safe) None Established (No adverse effects reported)
Chemical Forms
Cholecalciferol (D3 - Animal/Lichen), Ergocalciferol (D2 - Fungi) Phylloquinone (K1 - Green Plants), Menaquinones (K2: MK-4, MK-7 - Ferments/Animal)
Primary Biological Function
Calcitriol receptor (VDR) activation, intestinal calcium/phosphorus absorption, antimicrobial peptide synthesis Gamma-glutamyl carboxylase cofactor (Factors II, VII, IX, X), Osteocalcin carboxylation, Matrix Gla Protein (MGP) vascular calcification inhibitor
Deficiency Condition
Rickets (children), Osteomalacia (adults), Immune dysregulation Coagulopathy, Hemorrhage, Impaired bone density
Top Whole Food Sources
Sunlight UVB, Atlantic Salmon, Sardines, Egg Yolk, Fortified Milk Spinach, Kale, Broccoli, Brussels Sprouts, Natto (K2 MK-7), Parsley
Adult RDA / RDI
600 – 800 IU / day (15 – 20 µg) —
Target Serum 25(OH)D Level
30 – 50 ng / mL (75 – 125 nmol / L) —
Adult Adequate Intake (AI)
— 120 µg / day (Men) / 90 µg / day (Women)
Warfarin / Anticoagulant Interaction
— Direct competitive antagonist to Coumadin/Warfarin (requires consistent daily intake)

Other Alternatives to Compare

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