Vitamin K

Phylloquinone (K1), menaquinones (K2, MK-4/MK-7)

Fat-soluble vitamins

Aliases / common names

K1; K2; MK-4; MK-7; menaquinone

Natural food sources

Leafy greens, broccoli, soybean oil; fermented foods such as natto provide K2.

Main wellness functions

Required for normal blood clotting proteins and supports bone protein carboxylation.

Deficiency signs

Easy bruising, bleeding, prolonged clotting time; newborns are at risk without prophylaxis.

Recommended intake

AI adults: 90 mcg/day women, 120 mcg/day men. Children: about 30-75 mcg/day by age. Pregnancy: 90 mcg/day. No established UL.

Excess intake effects

Natural K1/K2 toxicity is low, but abrupt intake changes can affect warfarin control.

Contraindicated / caution groups

People taking warfarin or other vitamin K antagonist anticoagulants need consistent intake and medical guidance.

Common dosage forms

Capsules, tablets, drops; K2 MK-7 is common in bone-health formulas.

Common product strengths

K1 50-120 mcg; K2 MK-7 45-200 mcg; often combined with vitamin D3.

Use precautions

Keep daily intake consistent when anticoagulants are used. Fat-containing meals improve absorption.

Supplement notes

K1 and K2 differ in food sources and kinetics; claims for K2 should remain within bone/protein-support wording.

This information is for general nutrition education and product reference only. It does not replace medical diagnosis, treatment or individualized dietary advice.