Vitamin K

Fat-soluble vitamins

Coagulation · bone

Your intake

Today (logged)

0 mcg

0% of 120 mcg

Stack potential

0 mcg

0% of 120 mcg

Target

120 mcg

FDA Daily Value

Where you are on the ladder0% of target

What each level of vitamin k does

Approximate dose-response bands. Individual response varies — these are starting points, not prescriptions.

Severely lowYOU ARE HERE
0 mcg – 39.6 mcg
Well below target. Risk of deficiency symptoms tied to coagulation · bone.
Insufficient
39.6 mcg – 120 mcg
Below the recommended daily target. Long-term adequacy not assured.
Adequate
120 mcg – 180 mcg
Daily target met. Standard nutritional support for coagulation · bone.
Therapeutic
180 mcg – 240 mcg
Common for specific health goals. Check the evidence for your situation before sustaining this level.
Diminishing returns
240 mcg – +
Past the point where extra intake typically helps. Evidence for further benefit is thin.

Overview

Essential cofactor for gamma-carboxylation of glutamate residues on proteins involved in coagulation (factors II, VII, IX, X) and calcium handling (osteocalcin, matrix Gla protein). Two main families: K1 (phylloquinone) from green plants, K2 (menaquinones MK-4 through MK-13) from fermented foods and animal tissues.

Functions

●Cofactor for hepatic vitamin K-dependent clotting factors
●Activates osteocalcin (bone matrix) and MGP (vascular calcium handling)
●Modulates sphingolipid synthesis in nervous tissue
●Required for protein S anticoagulant function

Mechanism

GGCX enzyme uses vitamin K hydroquinone as cofactor to carboxylate glutamate residues, creating Gla residues that chelate calcium. Carboxylation oxidises K to its epoxide; VKORC1 recycles it. Warfarin inhibits VKORC1, depleting active K and inactivating clotting factors — the basis for its anticoagulant action.

Benefits

●Newborn vitamin K injection prevents hemorrhagic disease of newborn
●Adequate K2 status associates with lower coronary calcification (Rotterdam Study)
●MK-7 supplementation modestly improves bone mineral density in postmenopausal women
●May reduce arterial stiffness in CKD populations (small trials)

Deficiency

Overt deficiency causing bleeding is rare in adults due to gut bacterial K2 production and recycling. Subclinical insufficiency for extra-hepatic Gla proteins (osteocalcin, MGP) is more common.

Signs

●Easy bruising, prolonged bleeding (rare)
●Elevated prothrombin time / INR
●Possible reduced bone density
●Elevated undercarboxylated osteocalcin on specialty labs

At-risk groups

●Newborns (low placental transfer, sterile gut)
●Chronic antibiotic use (kills K2-producing bacteria)
●Fat malabsorption disorders
●Warfarin users (iatrogenic functional deficiency)

Excess

No established UL; toxicity from natural K1/K2 has not been reported. Synthetic menadione (K3) is hepatotoxic and not used in human supplements.

Signs

●Generally none from K1/K2
●Menadione (K3) — hemolytic anemia, jaundice (banned in adult supplements)

Forms

K1 (phylloquinone)
Plant source; preferentially used by liver for clotting
K2 MK-4
Animal/synthesised; short half-life (~1 h); dose multiple times/day
K2 MK-7
Fermented (natto); long half-life (~3 days); once-daily dosing works
K3 (menadione)
Synthetic; banned in human supplements; veterinary use only

Food sources

Cooked kale · 1 cup1,060 mcg K1
Cooked spinach · 1 cup890 mcg K1
Cooked broccoli · 1 cup220 mcg K1
Natto (fermented soy) · 1 oz300 mcg K2 (MK-7)
Hard cheese · 1 oz10 mcg K2
Egg yolk · 1 large30 mcg K2

Supplement forms

K2 as MK-7 has a much longer half-life (~3 days) than MK-4 (~1 hour) — once-daily MK-7 dosing is practical; MK-4 needs split doses to maintain levels. K1 is well-covered if you eat cooked greens regularly. Typical MK-7 dose: 90–180 mcg/day with a fat-containing meal.

Bioavailability

K1 from leafy greens is poorly absorbed (~10%); cooking with fat triples uptake. K2 from natto is the most bioavailable food form. All forms require bile and dietary fat for absorption.

Longevity relevance

The Rotterdam Study found dietary K2 (not K1) inversely associated with coronary calcification, CHD mortality, and all-cause mortality. Mechanism likely via MGP activation preventing vascular calcium deposition. K1 still matters for clotting but the longevity signal is concentrated on K2.

Relationships

Synergies (works better with)

Vitamin D · D drives calcium absorption; K2 directs it to bone via osteocalcin
Calcium · K2 activates MGP that prevents calcium deposition in arteries
Dietary fat · Required for micellar absorption of all vitamin K forms

Antagonists (competes with / inhibited by)

Warfarin (coumadin) · Vitamin K reverses anticoagulation — never adjust K intake without your prescriber
Long-term broad-spectrum antibiotics · Reduce K2-producing gut flora
High-dose vitamin E · Can interfere with K-dependent clotting at high doses (>1,000 IU/day)

References

About Vitamin K

Blood clotting and bone matrix protein activation.

Role: Coagulation · bone
Daily target: 120 mcg (DV)
Also called: vitamin k, vitamin k1, vitamin k2, phylloquinone, menaquinone, mk-4

Click here to learn more about Vitamin K →

Full explainer on Formulate Health — mechanisms, who's commonly deficient, food sources, evidence for supplementation.

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How Vitamin K acts on the body

The mechanisms and systems this nutrient feeds. Click any to drill into what runs on it.

Biochemical pathways

Bone★Clotting★Vitamin D Activation

Body systems

Cardio Bones★Longevity

Biomarkers that move with this nutrient

🩸 Vitamin D (25-OH)

★ = load-bearing / primary cofactor. Track these in My Journey.

Connect the dots

Top food sources of Vitamin K

Whole foods that contribute meaningfully (≥10% DV per 100 g serving). Click any food to see its full nutrient profile and what else it brings to the table.