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Thorne's Vitamin D + K2 Liquid delivers the two most clinically important fat-soluble vitamins for calcium regulation in a single, elegantly simple formula — combined in therapeutic ratios, suspended in medium chain triglyceride (MCT) oil for optimal absorption, and dispensed via a precision metered dropper that allows accurate, flexible dosing without measuring equipment.
Vitamin D3 (cholecalciferol) is the biologically active form of vitamin D — the same form produced endogenously in the skin following UV-B exposure — and is considerably more potent and better absorbed than the plant-derived D2 (ergocalciferol) form found in many lower-cost supplements. Vitamin D3 is essential for maintaining healthy serum calcium and phosphorus levels, supporting calcium absorption in the gastrointestinal tract, and maintaining bone mineralisation throughout all stages of life. It also plays a well-established role in supporting healthy immune function by activating vitamin D receptors (VDR) expressed throughout the immune system, including T-cells, B-cells, and macrophages.
Vitamin K2 (as MK-4, menatetrenone) is the form of vitamin K2 that has been most extensively studied clinically. Its inclusion alongside vitamin D3 is physiologically meaningful rather than merely convenient: vitamin D3 increases intestinal calcium absorption and raises circulating calcium levels, while vitamin K2 is required to activate the matrix Gla protein (MGP) and osteocalcin — two vitamin K-dependent proteins that direct calcium into bone tissue and away from soft tissues such as arterial walls and kidneys. Without adequate vitamin K2, calcium mobilised by vitamin D3 may not be optimally directed to its target tissues. Together, D3 and K2 operate as a functionally complementary pair — each supporting what the other initiates.
Thorne's formulation uses MK-4 specifically, which is the form naturally found in animal foods and has the greatest body of clinical research supporting its role in bone health. The MK-4 and D3 are suspended in MCT oil — a saturated medium-chain fat that provides an optimal lipid vehicle for fat-soluble vitamin absorption — and preserved with mixed tocopherols (natural vitamin E), which protect the oil-soluble vitamins from oxidation without the need for synthetic preservatives.
The self-dispensing metered top inverts to deliver individual drops with precision — no dropper to contaminate, no measuring required. Drops can be taken directly, added to food, or mixed into beverages. No refrigeration is required.
Thorne is one of the most stringently quality-controlled supplement manufacturers in the world, holding NSF Certified for Sport® status and manufacturing in NSF and TGA-registered GMP-certified facilities. All raw materials are tested upon receipt, with further in-process and finished-product testing for identity, potency, and purity.
What Sets This Product Apart
The D3/K2 liquid format offers three meaningful advantages over capsule-based equivalents. First, the liquid MCT oil base provides an inherently bioavailable lipid environment for fat-soluble vitamin absorption — particularly relevant for patients with compromised fat digestion or bile acid insufficiency. Second, the metered dropper allows precise, individualised dosing across a wide range — from 500 IU (1 drop) to 3,000 IU (6 drops) per day — without requiring multiple capsule sizes or split dosing gymnastics. Third, the MK-4 form of K2 distinguishes this from the many D3/K2 products using MK-7, providing the most clinically researched K2 form in a well-absorbed oil suspension. Thorne's manufacturing credentials place this product at the pinnacle of quality assurance for practitioner-grade supplements.
Supplement Facts
Serving Size: 2 drops Servings Per Container: 600
| Ingredient |
Amount Per Serving |
| Vitamin D3 (as cholecalciferol) |
1,000 IU (25 mcg) |
| Vitamin K2 (as menatetrenone, MK-4) |
200 mcg |
Other Ingredients: Medium chain triglyceride oil, mixed tocopherols.
Directions for Use
Take 2 drops one to three times daily, or as directed by your healthcare practitioner. Invert the bottle to dispense — drops will dispense automatically without shaking or removing the metered seal. May be taken directly, added to food, or mixed into beverages. Do not refrigerate.
Allergen Information
Free from gluten, dairy, soy, GMOs, artificial colours, flavours, and preservatives.
Cautions: Vitamin K2 interferes with the anticoagulant effect of warfarin (Coumadin) and related medications — do not take this product concurrently with anticoagulant therapy without consulting your prescribing physician. If pregnant, consult your healthcare practitioner before use. Keep out of reach of children. Store in a cool, dry place — do not refrigerate.
Practitioner Note
Recommended by Stephen Roigard, Naturopath & Clinical Nutritionist. The D3/K2 liquid format is particularly well suited to patients who have difficulty swallowing capsules, those with fat malabsorption (including post-cholecystectomy patients), and paediatric or elderly patients requiring highly flexible dosing. The MCT oil base is an excellent absorption vehicle, and the precision metered dispenser makes therapeutic dose titration straightforward. For patients with suspected or confirmed vitamin D insufficiency, the flexible dosing range (500–3,000 IU per day from this product alone) allows individualised correction protocols without requiring multiple products. The MK-4 form of K2 at 200 mcg per 2 drops is a clinically appropriate ratio relative to the D3 dose. The warfarin interaction is absolute — this product is contraindicated in patients on anticoagulant therapy without prior medical clearance.
This product is a dietary supplement intended to support general health and wellbeing. It is not intended to diagnose, treat, cure, or prevent any medical condition. This product has not been evaluated by Medsafe. If symptoms persist or worsen, consult a qualified healthcare practitioner.
