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Vitamin K2 is consistently underrepresented in people's routines, yet it sits at the centre of how the body handles calcium. We recommend this Thorne formulation specifically because it uses MK-4 at a meaningful dose, names the form clearly, and comes from a brand with rigorous manufacturing standards. For patients on higher-dose vitamin D3, or those managing bone density, it earns its place on clinical grounds rather than marketing ones.
About this product
Thorne Vitamin K2 Liquid (MK-4)
A high-potency pure vitamin K2 liquid delivering 1 mg of MK-4 per drop in an MCT oil base — the concentrated, tissue-active form of K2 that directs calcium into bone and out of arteries, with precision drop dosing for practitioners and individuals supplementing high-dose vitamin D who need serious K2 to match. This is not a maintenance-dose vitamin K supplement. This is the high-potency K2 liquid for people whose practitioners have recommended therapeutic-level MK-4 — typically those on high-dose vitamin D protocols, individuals with confirmed osteopenia or osteoporosis, post-menopausal women actively managing bone density, and anyone whose calcium metabolism requires aggressive K2 support rather than the token doses found in combination D3+K2 products. At 1 mg per drop and a suggested serving of 15 drops (15 mg MK-4), this product delivers MK-4 at doses approaching the levels used in Japanese clinical research on bone mineral density — where MK-4 at 45 mg daily demonstrated significant fracture reduction. Most K2 supplements provide 90 to 200 mcg. This provides milligrams.
The disconnect between typical K2 dosing and the doses studied for clinical outcomes is one of the most underappreciated gaps in the supplement market. Consumer K2 products deliver microgram-range doses of MK-7 — enough to provide baseline activation of K-dependent proteins, but potentially insufficient for individuals with significant bone loss, heavy vitamin D supplementation, or metabolic conditions that demand more aggressive calcium routing. MK-4 specifically is the form concentrated in human bone, brain, pancreas, and arterial tissue — the tissues where calcium direction matters most. It is the form that has been studied at therapeutic doses for bone mineral density outcomes. And it is the form that clears the bloodstream within hours, meaning adequate tissue-level activity requires either frequent dosing or high single doses. The liquid format makes this achievable where capsules cannot.
Thorne Vitamin K2 delivers pure MK-4 in MCT oil with a metered dispenser for precise dose control. One drop provides 1 mg — scale up to 5, 10, or 15 drops based on practitioner guidance and individual need. The MCT oil carrier ensures absorption without requiring dietary fat at the time of dosing. Three ingredients total: vitamin K2, MCT oil, and mixed tocopherols as antioxidant. No capsule shell, no fillers, no binders, no additives of any kind. The same Thorne quality — NSF Certified for Sport, four rounds of third-party testing, trusted by over 47,000 practitioners worldwide. 30 ml bottle — provides hundreds of drops for weeks to months of use depending on dosing.
People whose practitioners have prescribed high-dose vitamin D or who are actively managing bone density understand that microgram-level K2 is not proportionate to the calcium absorption their protocol is generating. Choosing milligram-dose MK-4 reflects a clinical-grade approach to calcium metabolism — matching K2 potency to the scale of the intervention it supports.
You gain therapeutic-dose K2, which removes the inadequacy of standard microgram-range K2 supplements and enables MK-4 delivery at levels approaching the doses studied in clinical bone density research
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What it does
Benefits
- 01
MK-4 is the form of vitamin K2 most concentrated in human tissue — bone, brain, pancreas, testes, and arterial walls — where it activates the calcium-directing proteins that determine whether absorbed calcium strengthens your skeleton or stiffens your blood vessels
- 02
At 1 mg per drop, this product enables dosing in the milligram range that clinical research on bone mineral density has studied — most notably the Japanese research protocol using 45 mg MK-4 daily that demonstrated significant fracture reduction in post-menopausal women
- 03
MK-4 has a short biological half-life (hours, not days), meaning tissue-level activity depends on adequate dosing rather than accumulation — the liquid format enables the multiple-milligram doses that capsules make impractical
- 04
MCT oil serves as both a lipid carrier enhancing fat-soluble vitamin absorption and a stable medium that preserves MK-4 potency without refrigeration
- 05
Vitamin K contributes to the maintenance of normal bones and normal blood clotting
Get the most from it
How to use
Take 15 drops one to three times daily, or as recommended by your healthcare professional. Invert the bottle and dispense individual drops directly under the tongue, onto food, or into a beverage. Dosing should be guided by your practitioner based on vitamin D intake, bone density status, blood calcium levels, and individual clinical need. Higher doses (15-45 mg daily) are used in clinical research but should only be undertaken with practitioner supervision. The metered dropper dispenses one drop at a time — note that reviewers report drops dispense slowly, so patience is required for larger serving sizes. Do not refrigerate. Do not use if taking anticoagulant medications (warfarin, acenocoumarol) — vitamin K directly opposes their mechanism of action. Consult your prescribing doctor before supplementing if on any anticoagulant therapy. If pregnant or breastfeeding, consult your healthcare professional. Store in a cool, dry place away from direct sunlight. The K2 for people who need milligrams, not micrograms — because when your vitamin D dose is clinical-grade, your K2 should be too.
What's inside
Ingredients
View full ingredient list
Vitamin K2 (as MK-4 / Menatetrenone) 1 mg per drop, Medium Chain Triglyceride Oil, Antioxidant (Mixed Tocopherols) Three ingredients. Nothing else.
Common questions
Frequently asked
What is the difference between MK-4 and MK-7?
MK-4 and MK-7 are both forms of vitamin K2 but differ in structure and behaviour. MK-4 has a shorter half-life and is the form most concentrated in human organs and tissues; most of the bone and cardiovascular research has used this form. MK-7 has a longer half-life and stays in circulation longer, which some prefer for once-daily convenience at lower doses. Neither is universally superior — the right choice depends on dose, purpose, and clinical context.
Is it safe to take alongside vitamin D3?
Yes, and the two are often taken together intentionally. Vitamin D3 increases calcium absorption from the gut; K2 helps ensure that calcium is directed into bone rather than soft tissue. If you are taking a high-dose vitamin D3 supplement, adding K2 is a reasonable and widely supported step — but discuss the combination with your clinician if you are on any medications.
Who should be cautious about taking vitamin K2?
Anyone taking anticoagulant medication — particularly warfarin (Coumadin) — should consult their doctor before taking any vitamin K supplement, as K vitamins can influence clotting pathways and affect INR levels. People on other blood-thinning agents should also seek medical advice first.
How long before I might notice a difference?
Vitamin K2's effects on bone density and arterial health are structural and accumulate over months to years; there is no short-term subjective change to expect. It is a long-game supplement best assessed through follow-up blood markers or imaging rather than how you feel day to day.
Should I take all three capsules at once or spread them through the day?
Check the packaging or follow your clinician's guidance for your specific dose. As a fat-soluble nutrient, splitting doses across meals that contain fat is a reasonable approach to support consistent absorption throughout the day.
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