Vitamin K2 MK-7 (Menaquinone-7)
SupplementThe medical score is slightly above the community score, as clinical studies show consistent biomarker effects [s3, s4, s7], while community reports are dampened by a notable accumulation of adverse event reports (palpitations, sleep disturbances) associated with higher-dose products [c1, c2, c3].
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TL;DR
Vitamin K2 MK-7 is the most evidence-backed K2 form: multiple RCTs consistently show osteocalcin activation (ucOC reduction up to 65%) and slowed bone density loss in postmenopausal women, and a meta-analysis of 14 RCTs suggests reduced arterial stiffness — though hard endpoints like fracture rates remain unproven. The combination with vitamin D3 is pharmacologically sound and well-established in the community; for most users, 90–180 µg daily with a fatty meal is sufficient. Critical caveat: anyone on vitamin K antagonists like warfarin must not use MK-7 without close INR monitoring — and the community-documented side effects at high doses (palpitations, sleep disruption, intense restlessness) are credible enough to firmly discourage megadosing.
Description
Highly bioavailable form of vitamin K2 with long half-life; activates osteocalcin and MGP for bone preservation and inhibition of arterial calcification [s1, s2, s3].
Vitamin K2 MK-7 (menaquinone-7) is a long-chain form of vitamin K2 produced predominantly through bacterial fermentation. The richest natural source is natto (fermented soybeans) with up to 1103 µg MK-7 per 100 g [s6]. Compared to MK-4, MK-7 is characterized by a considerably longer half-life of approximately 72 hours (3 days), enabling stable blood levels with once-daily dosing in the microgram range [s5]. The primary mechanism of MK-7 is the activation (carboxylation) of vitamin K-dependent proteins: osteocalcin in bone and matrix Gla protein (MGP) in vessel walls. After carboxylation, osteocalcin binds calcium in the bone matrix; after carboxylation, MGP inhibits the deposition of calcium in arteries [s1, s2]. In a three-year placebo-controlled RCT in postmenopausal women with osteopenia, MK-7 (180 µg/day) significantly reduced the age-related decline in bone mineral density and improved bone structural parameters [s3]. Undercarboxylated osteocalcin decreased by 65.2% in the MK-7 group versus 0.03% in the placebo group [s4]. For cardiovascular endpoints, a Frontiers meta-analysis of 14 RCTs provides evidence of a slowing of arterial stiffness [s7]. However, a large RCT (CIRCULATIONAHA 2021) found no significant effect of 720 µg MK-7 + 25 µg vitamin D on the primary endpoint aortic valve calcium score in men with already advanced aortic valve calcification [s8]. The evidence base for hard cardiovascular endpoints is therefore considered incomplete. Vitamin D3 increases the requirement for vitamin K2, as it upregulates the production of vitamin K-dependent proteins; combined supplementation is discussed in the specialist literature [s9, s10]. The BfR explicitly notes the risk of interactions with vitamin K antagonists and recommends medical supervision for affected individuals [s12].
Legal Status (DE)
In Germany, Austria, and Switzerland, vitamin K2 MK-7 is marketable as an over-the-counter food supplement. It is not subject to a medicinal product authorization procedure. The BfR recommends a maximum amount of 25 µg MK-7 per daily serving recommendation of a food supplement [s12]. In the EU, a novel food authorization has been granted for certain synthetic MK-7 forms [s13].
Mechanism of Action
MK-7 acts as a cofactor of gamma-glutamyl carboxylase, an enzyme that converts glutamate residue side chains in vitamin K-dependent proteins to gamma-carboxyglutamate (Gla) [s1, s2]. This carboxylation step is necessary for the proteins to bind calcium. In bone, carboxylated osteocalcin (cOC) promotes the incorporation of hydroxyapatite (calcium phosphate) into the bone matrix. In MK-7 deficiency, predominantly undercarboxylated osteocalcin (ucOC) circulates, which cannot fulfill this function [s3, s4]. MK-7 supplementation measurably reduces ucOC [s4]. In vessel walls and soft tissues, carboxylated MGP (matrix Gla protein) prevents calcium deposition. Undercarboxylated MGP (dp-ucMGP) is considered a biomarker for vascular calcification risk [s7, s8]. MK-7 significantly reduces dp-ucMGP in clinical studies [s7]. In the coagulation cascade, vitamin K activates factor II (prothrombin), VII, IX, and X as well as the anticoagulant proteins C and S. This function explains the clinically relevant interaction with vitamin K antagonists (warfarin, phenprocoumon) [s14, s15]. Due to its long half-life (~72 h), MK-7 exerts a more pronounced extrahepatic effect than MK-4, as it circulates longer in bone, vascular, and other peripheral tissues [s5].
Dosing
Knochengesundheit / Osteoporose-Prävention
- Dose
- 180 µg MK-7
- Frequency
- 1× täglich
- Route
- oral
- Duration
- langfristig (mind. 3 Jahre in Studiensetting)
- Timing
- Preferably with a fat-containing meal (fat-soluble vitamin)
- With food
- empfohlen
Vaskuläre Kalziumregulation / Arterielle Gesundheit
- Dose
- 90–180 µg MK-7
- Frequency
- 1× täglich
- Route
- oral
- Duration
- langfristig
- Timing
- With a fat-containing meal
- With food
- empfohlen
Allgemeine Versorgung / Kombination mit Vitamin D3
- Dose
- 75–200 µg MK-7
- Frequency
- 1× täglich
- Route
- oral
- Duration
- fortlaufend
- Timing
- Concurrently with vitamin D3 administration with a fat-containing meal
- With food
- empfohlen
The BfR recommends a maximum amount of 25 µg MK-7 per daily serving recommendation in food supplements for the general population [s12]. The CRN sets the no-observed-adverse-effect level at 375 µg/day [s11]. In clinical studies, doses of up to 720 µg/day have been used without serious adverse events [s8]. Self-experiments with several thousand µg daily are associated with adverse event reports [c2].
MK-7 is fat-soluble and must be taken with a fat-containing meal to ensure absorption [s5]. Individuals on vitamin K antagonist therapy (warfarin, phenprocoumon/Marcumar) may only take MK-7 under close medical INR monitoring [s14, s15].
Side Effects
| Side Effect | Frequency | Severity |
|---|---|---|
| Herzpalpitationen, Herzrasen Reported multiple times in Reddit threads at doses ≥100 µg; possible cause is a shift in calcium-magnesium balance or calcium mobilization through enhanced osteocalcin/MGP activation [c1, c2, c3]. Clinical RCTs at doses ≤180 µg do not show this phenomenon systematically. | gelegentlich | moderat |
| Schlafstörungen, Nervosität, innere Unruhe Repeatedly described in community reports, particularly at higher doses or evening administration [c1, c3]. Mechanistically not fully explained; possibly an individual response to calcium shifts. | gelegentlich | leicht |
| Gastrointestinale Beschwerden (Übelkeit, Bauchschmerzen) Not recorded as a frequent event in toxicity studies and clinical trials at standard doses [s11]. Individual community reports exist [c1]. | selten | leicht |
| Störung der Antikoagulations-Einstellung (INR-Veränderung) As little as 10 µg MK-7/day can clinically significantly affect INR in patients on vitamin K antagonists (warfarin, Marcumar/phenprocoumon) and lead to thrombotic events [s14, s15]. | häufig | schwer |
| Allergische Reaktionen (Geraniol-Allergie) Synthetic MK-7 derived from geraniol sources can trigger allergic reactions in sensitized individuals [c4]. | selten | moderat |
Contraindications
MK-7 antagonizes the anticoagulant effect of VKAs and can completely reverse anticoagulation, with risk of fatal thromboembolism. Contraindicated without intensive INR monitoring by a physician [s14, s15].
Geraniol-based MK-7 synthesis may trigger allergic reactions in sensitized individuals [c4].
Insufficient safety data exist for high MK-7 doses during pregnancy and lactation. Standard doses are considered safe [s11].
Interactions
Synergistic
Vitamin D3 increases the synthesis of vitamin K-dependent proteins (osteocalcin, MGP), thereby raising the requirement for MK-7 for their complete carboxylation. Combined intake is scientifically discussed and appears more beneficial for bone and vascular health than either agent alone [s9, s10].
MK-7 (via cOC and cMGP) regulates calcium distribution in the body: promoting deposition in bone and inhibiting deposition in vessels. Combined supplementation of calcium and MK-7 is advisable to minimize soft tissue calcification [s1, s2].
Magnesium is an important cofactor for bone matrix formation and acts complementarily to MK-7, which carboxylates osteocalcin. The combination synergistically supports complete bone mineralization.
The combination of MK-7 with omega-3 fatty acids is recommended in practice for bone and vascular health, as both compounds exert anti-inflammatory and cardioprotective effects. Omega-3 also improves MK-7 bioavailability as a lipophilic carrier.
Caution
MK-7 reduces the anticoagulant effect of VKAs through competition at the vitamin K cycle. As little as 10 µg/day can clinically significantly alter INR. Strict contraindication without medical supervision [s14, s15].
Orlistat reduces absorption of fat-soluble vitamins including MK-7; concomitant use may result in inadequate vitamin K2 supply. A time interval or dose adjustment is required [s11].
Broad-spectrum antibiotics can reduce intestinal microbiota that produce menaquinones, thereby impairing endogenous K2 synthesis. Clinical relevance is low with short-term use but possible with long-term antibiotic therapy [s6].
In patients on statin therapy, vitamin K2 status may be reduced, as statins inhibit the mevalonate pathway, which is also relevant for menaquinone synthesis. Adequate MK-7 supply is particularly recommended in this patient population.
Studies
Tier A — High Evidence
Outcome: Vascular calcification and arterial stiffness
Effect Size: Significant reduction of dp-ucMGP; evidence of slowed arterial stiffening; no consistent effect on calcification scores across all subgroups
Outcome: Bone mineral density (BMD) of lumbar spine and femoral neck; bone structural parameters
Effect Size: Significant attenuation of BMD loss in MK-7 group (180 µg/day) vs. placebo; improvement in hip strength index (p<0.05)
Outcome: Undercarboxylated osteocalcin (ucOC) as a marker of vitamin K2 activity
Effect Size: ucOC reduction -65.2 ± 23.5% (MK-7) vs. -0.03 ± 38.5% (placebo), p<0.01
Outcome: Change in aortic valve calcification score (AVC)
Effect Size: No significant difference in primary endpoint AVC score between 720 µg MK-7 + 25 µg vitamin D vs. placebo; dp-ucMGP significantly reduced (biomarker endpoint positive)
Tier B — Moderate Evidence
Outcome: Synergism of vitamin D and vitamin K2 for bone and vascular health
Effect Size: Narrative synthesis; no independent effect size
Outcome: Arterial calcification and cardiovascular mortality
Effect Size: High K2 intake (particularly MK-7) associated with ~50% reduction in arterial calcification and cardiovascular mortality (observational study, not RCT)
Tier C — Low Evidence
Outcome: Safety and toxicology of MK-7
Effect Size: No toxic event at 5000 mg/kg acute dose (animal model); no adverse event up to 375 µg/day in humans
Community Evidence
Top reported benefits
- Subjectively stronger bones / reduced complaints in osteoporosis
- Good complement to vitamin D3, perceived synergy
- Reduction of muscle cramps (anecdotal)
- Generally good tolerability at low doses (≤100 µg)
Top reported issues
- Heart palpitations and racing heart, especially at higher doses
- Sleep disturbances and inner restlessness / nervousness
- Intense unpleasant feelings of energy / agitation
- Lack of clarity regarding correct dosage in many products
Several prominent Reddit threads warn of significant adverse effects with incorrect or excessive dosing (e.g., 5000 µg/day over weeks), with symptoms such as shortness of breath and heart palpitations [c2]. Some users report that symptoms only resolve after discontinuation [c2]. The interaction with anticoagulants is present in German-language forums but not sufficiently well known [c5]. Users discuss whether magnesium supplementation can mitigate the adverse effects [c3].
Scientific Sources
- Molecular Pathways and Roles for Vitamin K2-7 as a Health-Promoting Nutraceutical
Halder M, Petsophonsakul P, Akbulut AC, et al. (2022). Frontiers in Nutrition / PMCBDOI - Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study
Geleijnse JM, Vermeer C, Grobbee DE, et al. (2004). Journal of NutritionBPMID:15514282DOI - Safety evaluation of vitamin K2 (menaquinone-7) via toxicological tests
Nakamura E, Aoki M, Watanabe F, et al. (2024). Scientific ReportsCDOI - BfR-Stellungnahme 065/2023: Hochdosierte Nahrungsergänzungsmittel mit Vitamin D – Empfehlung zu Vitamin K2
Bundesinstitut für Risikobewertung (BfR) (2023). BfRALink - US firm wins EU novel foods approval for vitamin K2
NutraIngredients Editorial (2015). NutraIngredientsBLink - Effect of vitamin K2 on the anticoagulant activity of warfarin
PMC Editorial (2016). PMC / Thrombosis JournalBLink - Vitamin K2 MK-7 and anticoagulant interference: clinical contraindication guidance
Dr Kumar Discovery Editorial (2024). Dr Kumar DiscoveryCLink - Effects of vitamin K supplementation on bone mineral density at different sites and bone metabolism: a meta-analysis and systematic review of RCTs
Zhang Y, Liu Z, Chen X, et al. (2024). PMC / FrontiersALink - CRN updates vitamin K2 MK-7 intake limits – HOI 375 µg/day
NutraIngredients Editorial (2025). NutraIngredientsBLink - The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health
van Ballegooijen AJ, Pilz S, Tomaschitz A, et al. (2017). International Journal of Endocrinology / PMCBPMID:29138634DOI - Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women
Knapen MH, Drummen NE, Smit E, et al. (2013). Osteoporosis InternationalAPMID:23525894DOI - The effect of vitamin MK-7 on bone mineral density and microarchitecture in postmenopausal women with osteopenia, a 3-year randomized, placebo-controlled clinical trial
Rønn SH, Harsløf T, Pedersen SB, et al. (2021). Osteoporosis InternationalAPMID:33030563DOI - MK-7 vs MK-4: Bioavailability and Half-Life Comparison
MediQ7 Editorial (2023). MediQ7 BlogCLink - Lebensmittel mit Vitamin K2: Natto als reichste natürliche Quelle
Redaktion zaehne-bleachen.de (2024). zaehne-bleachen.deCLink - Vitamin K supplementation and vascular calcification: a systematic review and meta-analysis of randomized controlled trials
Maresz K, Zawadzki M, Gajda M, et al. (2023). Frontiers in NutritionADOI - Vitamin K2 and D in Patients With Aortic Valve Calcification: A Randomized Double-Blinded Clinical Trial
Viedt C, Göbel S, Pleger ST, et al. (2022). CirculationADOI - The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Review
van Ballegooijen AJ, Pilz S, Tomaschitz A, et al. (2017). International Journal of EndocrinologyBPMID:29138634DOI
Community Sources
Storage
Unopened
Store in a dry, cool place (15–25 °C), protected from direct light and heat.
Opened
Keep bottle/blister tightly closed; protect powder and oil forms from moisture and light.
Notes
MK-7 is light-sensitive and can be degraded by UV radiation. Oil-based drop formulations should be stored in the refrigerator after opening and consumed within the indicated period.