Products · Vitamins & minerals · Thorne
Thorne Vitamin D + K2 Liquid
Reader ratings
A liquid D3 + K2 with a short label (1,000 IU of D3 and 200 mcg of MK-4 per 2 drops) at a low cost per day. We have not confirmed an NSF listing for the liquid, and K2 can interfere with warfarin.
Best for People who want to set the D3 dose drop by drop and want K2 as MK-4, and do not take warfarin or other blood thinners.
- Our quality rating
- Fair (3 of 5)
- Price range
- Mid-range
- Size
- Liquid dropper bottle, about 1,200 drops (600 servings of 2 drops)
approx. $34 for the bottle (about 600 servings of 2 drops)
See it on Thorne’s site →We are not affiliated with Thorne. This link goes to the maker’s own page, with no tracking code. How we're funded.
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Your review
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How we evaluated it
Why we chose it What put it on our list
- The label is short and every amount is stated: vitamin D3 25 mcg (1,000 IU) and vitamin K2 as menatetrenone (MK-4) 200 mcg per serving of 2 drops, in medium-chain triglyceride oil preserved with mixed tocopherols.
- It is cheap per day. At $34 for about 600 servings, 1,000 IU of D3 costs roughly $0.06 a day, and 2,000 IU (4 drops) about $0.11.
- Thorne has many products in NSF’s Certified for Sport database. We opened the entries for D-5,000, Basic Nutrients 2/Day, Zinc Picolinate 30 mg and Iron Bisglycinate. The Vitamin D + K2 entry there is a capsule, not this liquid.
- Thorne’s page names the interaction plainly: vitamin K interferes with anticoagulant drugs such as Coumadin, and the two should not be used together.
Trade-offs What to weigh before you buy
- We have not confirmed independent testing for this product. Thorne’s page says it is “third-party tested and certified” without naming a certifier. NSF’s Certified for Sport database lists a “Thorne Vitamin D + K2” capsule (60 count, one lot), not the liquid, and NSF’s dietary supplement listings could not be reached from our tools.
- K2 can interfere with warfarin (Coumadin) and similar blood thinners, and Thorne says to avoid using them together. Ask your prescriber first, or choose a vitamin D3-only product.
- The label allows 2 drops up to three times a day. That is up to 3,000 IU of D3 and 600 mcg of K2 a day, close to the 4,000 IU upper limit for vitamin D.
- The case for K2 is thin, and this is a different form from the one studied. Our K2 page describes one 3-year trial of 180 mcg of MK-7 a day and says protection of the arteries is unproven. It says MK-4 has a half-life of only about 1 to 2 hours and calls for multiple daily doses of 15 to 45 mg, against 200 mcg here.
What to know Details worth knowing first
Vitamin D3 is the form most people supplement, and our supplementation guide covers doses and testing. K2 is the add-on: our K2 page describes one trial in which MK-7 went with less bone loss in postmenopausal women, and says its effect on arteries is unproven. This product uses MK-4, a different form.
The appeal here is the price per day and a dropper that lets you set the dose. The doubts are the certifier listing we have not been able to confirm for the liquid, and the interaction with warfarin.
For what seals can and cannot tell you, see how to tell if a supplement is pure.
Quality & testing How it measures up against our checklist
- Certificate of analysis
- No
| What we checked | What we found |
|---|---|
| Third-party tested Maker’s claim | Not confirmed. Thorne’s page says the product has been “third-party tested and certified”, and its testing FAQ describes the NSF Contents Certified mark in general terms, but neither names a certifier for this liquid. NSF Certified for Sport lists a Thorne Vitamin D + K2 capsule, not this liquid. NSF’s dietary supplement listings (info.nsf.org) could not be reached from our tools. |
| A certificate of analysis Not verified | None on Thorne’s page. Thorne says it tests each ingredient for identity, purity and potency, including heavy metals, pesticides and microbes, and publishes no results. |
| The right form Maker’s claim | Vitamin D3 25 mcg (1,000 IU) and vitamin K2 as menatetrenone (MK-4) 200 mcg per 2 drops. |
| A plain label Maker’s claim | Two active ingredients with amounts, and two named other ingredients. No proprietary blend. |
| Disclosed extras Maker’s claim | Medium-chain triglycerides and mixed tocopherols. Thorne lists it as gluten-free, dairy-free and soy-free. |
| K2 and blood thinners Maker’s claim | Thorne’s warning: vitamin K interferes with anticoagulants such as Coumadin, so concurrent use should be avoided. |
What the labels mean
- Verified We opened an independent record that confirms it: a certifier’s listing, a regulator’s list or a lab report. It is linked under Sources.
- Maker’s claim The maker says so on its own page or label. We read it but found no independent record.
- Not verified We looked and could not confirm it, or the maker does not say. Treat it as unknown.
Sources Where our facts come from
- Thorne Vitamin D + K2 Liquid product page. Maker’s page. Price, label amounts, directions, testing statements and warning as seen 2026-10-22. Open ↗
- NSF Certified for Sport listing: Thorne Vitamin D + K2 (capsule, 60 count). Certifier or regulator listing. A capsule with one lot (417489). Not the liquid on this page. Open ↗
Alternatives Other options to compare
- Core Med Science Vitamin D3 2,000 IU + K2 Capsule with 100 mcg of K2 as MK-7 (K2 can interfere with warfarin) and an NSF listing; about $17 for 60 capsules, no public batch results.
- Momentous Vitamin D3 2000 IU Vitamin D3 on its own, with an NSF listing and public lot certificates; about $20 for 60 capsules.