Vitamin K2 (MK-9)

Long-chain menaquinone with extended half-life and unique tissue distribution patterns

Scientific nameMenaquinone-9 FormulaC51H72O2 Molecular weight716.13 g/mol CAS523-39-7

85 absorption score

7 safety / 10

120 USD per month

5 documented interactions

Check it against something

Evidence level B

Vitamin K2 (MK-9) with:

59 out of 100

Needs attention Separate by 2-4 hours to avoid the interaction below.

Check it against your whole stack →

What it does

mechanism and evidence for each claim

Extended half-life

Longer duration of action than MK-4 or MK-7

Longer aliphatic side chain increases tissue retention Evidence B-grade Sustained over days

Enhanced tissue penetration

Better distribution to various tissues than shorter forms

Lipophilic properties enhance cellular uptake Evidence C-grade 2-4 weeks

Sustained cardiovascular protection

Long-lasting arterial calcium regulation

Extended activation of matrix Gla protein Evidence C-grade 4-8 weeks

Comprehensive bone support

Prolonged osteocalcin activation for bone health

Extended carboxylation of bone proteins Evidence C-grade 6-12 weeks

Reduced dosing frequency

May allow for less frequent supplementation

Extended tissue residence time Evidence C-grade Ongoing

Others take these for the same thing

Same goal, different mechanism — check any of them against this one

Calcium Bone health & muscle function 1,000-1,200 mg A 30% Turmeric Anti-inflammatory & antioxidant 300-1000mg A 3% Coenzyme Q10 (CoQ10) Heart health & cellular energy 100-200mg A 10% Vitamin D3 Bone health & immune support 1000-2000 IU A 85% Fish Oil (EPA/DHA) Heart & brain health 1-2g EPA/DHA A 85% Collagen Peptides Skin health & joint support 5-15g B 85%

Every pair we checked

12 combinations scored by the engine

Vitamin K2 (MK-9) + Vitamin D3 High vitamin A may interfere with K2 function Needs attention 59

Vitamin K2 (MK-9) + Vitamin C (Ascorbic Acid) High vitamin A may interfere with K2 function Needs attention 63

Vitamin K2 (MK-9) + Vitamin B12 (Methylcobalamin) High vitamin A may interfere with K2 function Needs attention 63

Vitamin K2 (MK-9) + Caffeine No documented interaction either way No known interaction 70

Vitamin K2 (MK-9) + Creatine Monohydrate No documented interaction either way No known interaction 70

Vitamin K2 (MK-9) + Whey Protein No documented interaction either way No known interaction 70

Vitamin K2 (MK-9) + Turmeric No documented interaction either way No known interaction 70

Vitamin K2 (MK-9) + Lactase Improved calcium absorption when consuming dairy Works better together 82

Vitamin K2 (MK-9) + Bovine Collagen Essential for collagen synthesis and cross-linking Works better together 82

Vitamin K2 (MK-9) + DHA Prevents oxidation of DHA and enhances stability Works better together 82

Vitamin K2 (MK-9) + Magnesium Oxide Required for vitamin K-dependent enzyme function Works better together 87

Vitamin K2 (MK-9) + Calcium Carbonate K2 directs calcium to appropriate tissues Works better together 99

Dosage

With fat containing meal

Daily50-200 mcg (experimental)

Experimental50-200 mcg

Theoretical100-500 mcg

Research basedLimited data available

Combination25-100 mcg with other K2 forms

Before you take it

VeganYes

When to expect it

First Effects2-4 weeks for initial protein carboxylation

Peak Benefits8-16 weeks for sustained tissue effects

Deficiency DevelopmentMonths (similar to other K2 forms)

Toxicity OnsetNo known toxicity (limited data)

How to measure it

$150-300

MarkerUndercarboxylated osteocalcin (ucOC) and matrix Gla protein

OptimalSimilar targets to other K2 forms

FrequencyEvery 6-12 months if using experimentally

What people actually reported to the FDA

CAERS, 33 reports naming it as the suspect

Most reported effects

Pain 3

Chest pain 3

Death 3

Nephrolithiasis 3

Atrial fibrillation 3

Named as the suspect 33 reports of 92 that mention it at all

Serious outcome 85% hospitalisation, emergency room or worse

Other Serious or Important Medical Event21

Hospitalization17

Visited Emergency Room8

Reports are voluntary and unverified — they record what someone experienced while taking something, not what the compound caused. Counts skew towards products people take a lot of, and a serious outcome is more likely to be reported than a mild one, so these are not rates. How we filter them →

What actually reaches you

The label counts the carrier, your body does not

Absorption Very high 85 of 100 · best absorbed form of this compound

Delivered daily 0.1 mg

Cost per 1 mg delivered $37.65 comparative — uses the absorption score, not a measured percentage

Works better with

3 documented

Vitamin D3

Both required for proper calcium utilization

D3 produces proteins that K2 activates · level A (for vitamin K2 generally)

Magnesium

Required for vitamin K-dependent enzyme function

Cofactor for carboxylation reactions · level B (theoretical for MK-9)

Calcium

K2 directs calcium to appropriate tissues

Protein carboxylation enables calcium binding · level A (for vitamin K2 generally)

What not to take with Vitamin K2 (MK-9)

2 documented

Vitamin A Excess

High vitamin A may interfere with K2 function

Competition for similar metabolic pathways · mild (theoretical for MK-9) significance

Vitamin E Excess

High vitamin E may interfere with K2 metabolism

Interference with K2 recycling · mild (theoretical for MK-9) significance

Medication interactions

Discuss these with a pharmacist before combining

warfarin-anticoagulants Unknown

Interaction potential unknown for MK-9

What to do: Extreme caution, avoid without medical supervision

antibiotics-broad-spectrum Minor

May reduce gut bacteria production of MK-9

What to do: Consider supplementation during antibiotic use

Available forms

bioavailability compared

Best absorbed form of Vitamin K — 85% against 3 alternatives. Compare all forms →

Menaquinone-9 (MK-9) 85

Menaquinone-9 (MK-9): Extended half-life, Unique properties, Advanced technology, Sustained action

Food sources

before you supplement

Fermented foods (trace amounts) <1 mcg per serving · 60

Certain fermented cheeses Variable, very small amounts · 70

Note: Meaningful amounts only available as supplement Food sources negligible · 85

Too little

deficiency signs

Same as general vitamin K2 deficiency:
Arterial calcification progression
Reduced bone mineral density
Poor calcium regulation
Increased fracture risk
Cardiovascular disease progression

Too much

toxicity signs

No known toxicity (limited data)
Theoretical accumulation effects unknown
No interactions with anticoagulants established
Safety profile assumed similar to other K2 forms
Long-term effects completely unknown

Who benefits most

k2-researchers-enthusiasts

Interest in cutting-edge vitamin K2 forms

50-200 mcg daily (experimental)

extended-release-preference

Want longer-acting supplements for convenience

100-300 mcg every few days (theoretical)

mk7-non-responders

May benefit from different K2 form if others ineffective

100-200 mcg daily (experimental)

advanced-supplementation

Want comprehensive K2 spectrum supplementation

50-150 mcg daily (in combination)

Where to buy it

compare forms first

Look for Vitamin K2 (MK-9) at 50-200 mcg (experimental) per serving. The form that matters here is Menaquinone-9 (MK-9).

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How it works

Same carboxylation mechanisms as other K2 forms
Extended tissue residence due to longer lipophilic chain
Theoretical enhanced cellular uptake and retention
Sustained activation of vitamin K-dependent proteins
May have unique tissue distribution patterns
Potentially superior for deep tissue penetration

Key findings

what the evidence supports

Limited to biochemical and theoretical studies
Longer half-life demonstrated in preliminary research
Tissue distribution differs from shorter-chain menaquinones
Safety and efficacy in humans largely unknown

Sources: NIH Examine.com · data reviewed 2026-08-02

Compiled by Denis, who maintains this database and holds no medical qualification — every figure here is sourced or derived, never asserted. How we calculate it →

Common questions

What are the benefits of Vitamin K2 (MK-9)?

Documented effects: Extended half-life; Enhanced tissue penetration; Sustained cardiovascular protection; Comprehensive bone support. Longer duration of action than MK-4 or MK-7

How much Vitamin K2 (MK-9) should you take per day?

The common daily range is 50-200 mcg (experimental). By goal — experimental: 50-200 mcg; theoretical: 100-500 mcg; research based: Limited data available; combination: 25-100 mcg with other K2 forms.

When is the best time to take Vitamin K2 (MK-9)?

With fat containing meal. First effects are typically reported within 2-4 weeks for initial protein carboxylation.

What are the side effects of Vitamin K2 (MK-9)?

At excessive doses: No known toxicity (limited data), Theoretical accumulation effects unknown, No interactions with anticoagulants established, Safety profile assumed similar to other K2 forms, Long-term effects completely unknown. Safety rating at normal doses is 7 out of 10.

What should you not take with Vitamin K2 (MK-9)?

Separate it from Vitamin A Excess, Vitamin E Excess by two to four hours. High vitamin A may interfere with K2 function

Does Vitamin K2 (MK-9) interact with medications?

Documented interactions with warfarin-anticoagulants, antibiotics-broad-spectrum. Discuss these with a pharmacist before combining.

How do you know if you need Vitamin K2 (MK-9)?

The marker is Undercarboxylated osteocalcin (ucOC) and matrix Gla protein, optimal range Similar targets to other K2 forms. Common deficiency signs: Same as general vitamin K2 deficiency:, Arterial calcification progression, Reduced bone mineral density, Poor calcium regulation.

Taken for

52 Heart

Fish Oil (EPA/DHA) · EPA · Olive Oil Extract

38 Joints & Bones

Vitamin D3 · Calcium Carbonate · Bovine Collagen