Overview
Short-acting K2 form used at high dose in Japanese osteoporosis protocols.
- Whole-food sources (animal products for fat-soluble and B-complex vitamins; produce for water-soluble vitamins)
- Fortified foods (cereals, dairy, plant milks, nutritional yeast)
- Multivitamins or stand-alone supplements in synthetic or food-derived form
- Capsule or softgel
- Sublingual tablet or liquid
- Methylated active form for sensitive individuals
- Multivitamin matrix
Forms & variants of Vitamin K2 (MK-4)
Different chemical forms of Vitamin K2 (MK-4) behave differently. Browse each form's mechanism, bioavailability, and best-use context.
Mechanism of action
Same carboxylation cofactor as MK-7 but shorter half-life; tissue-specific accumulation.
- · Same carboxylation cofactor as MK-7 but shorter half-life
- · tissue-specific accumulation
Effects on the body
Organ system effects
Vitamin K2 (MK-4) contributes to bone mineralization, osteoblast activity, or calcium-phosphate homeostasis.
Evidence-based benefits
Reduces vertebral fractures at 45 mg/d (Japanese trials)
Moderate evidencePotential side effects
- · Vitamin K2 (MK-4) is generally well-tolerated at evidence-based doses
- · Mild GI discomfort (nausea, loose stools, or bloating) possible at higher intakes
- · Headache or transient fatigue reported by a small fraction of users
- · Allergic or hypersensitivity reaction (rash, itching, swelling)
- · Sleep disturbance if taken late in the day
- · Discontinue and seek medical advice if symptoms are severe, persistent, or include difficulty breathing
Drug interactions
Supplement interactions
- A high-quality multivitaminCovers micronutrient cofactors that support most supplement pathways.
- Omega-3 (EPA/DHA)Foundational anti-inflammatory support that complements most regimens.
No specific avoidances listed.
Dosing & bioavailability
Where to buy
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Third-party testedIndependently verified Vitamin K2 (MK-4) — look for USP, NSF, or Informed Sport seals on the label for purity and dose accuracy.Vitamin K2 (MK-4) third party tested NSF
CapsulesPre-measured Vitamin K2 (MK-4) capsules — easiest for travel and consistent daily dosing without scoops or scales.Vitamin K2 (MK-4) capsules
PowderBulk unflavored Vitamin K2 (MK-4) powder — best cost-per-gram and flexible dosing for stacking or mixing into drinks.Vitamin K2 (MK-4) powder unflavored
Best sellersMost-purchased Vitamin K2 (MK-4) products on Amazon — a quick way to see what's reviewed widely before you commit.Vitamin K2 (MK-4) best sellerScientific evidence8Show studiesHide studies
MK-4 for osteoporosis in postmenopausal women
Iwamoto J, et al.
Review of MK-4 in osteoporosis (Japan).
Reduced fracture risk at pharmacologic doses (45 mg/d).
PubMed: Vitamin K2 (MK-4) — Reduces vertebral fractures at 45 mg/d
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PubMed: Vitamin K2 (MK-4) — randomized controlled trial
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PubMed: Vitamin K2 (MK-4) — meta-analysis
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PubMed: Vitamin K2 (MK-4) — pharmacokinetics
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PubMed: Vitamin K2 (MK-4) — dose response
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Google Scholar: Vitamin K2 (MK-4) — clinical evidence
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