Thorne Vitamin D + K2 Liquid is vitamin D you measure in drops rather than swallow in a softgel. It is a small dropper bottle of D3 and K2 suspended in MCT oil: two drops deliver 1,000 IU of vitamin D3 and 200 mcg of vitamin K2, and you can put them in water, drip them onto food, or take them straight off the dropper. For anyone who dislikes pills, or who wants to nudge their dose up or down without buying a new bottle, the liquid format is the whole appeal.
The form is sensible for the vitamin. D3 is fat-soluble, so an oil base helps it absorb, and 1,000 IU is a maintenance dose that sits comfortably inside the tolerable upper limit rather than the deficiency-correction territory some products reach for. This review turns on two checkable things: what the label actually discloses and certifies, and whether the K2 form and the dropper live up to the rest. Here’s the full scorecard.
At a glance
Quick verdict
Thorne Vitamin D + K2 Liquid is a genuinely fair pick, and it earns its place as the combo and liquid option for straightforward reasons: it does the fundamentals right. It uses D3, the more effective form of vitamin D, at a sensible 1,000 IU maintenance dose well inside the upper limit; it pairs it with a meaningful 200 mcg of K2; it puts both in MCT oil, which suits a fat-soluble vitamin; it discloses everything with no proprietary blend; it is vegetarian; and it is NSF Contents Certified for label accuracy and purity. At about $0.06 a serving it is also excellent value, and the drop format is the most dose-flexible way to take vitamin D we reviewed.
What keeps it at 81 — Acceptable — is honest and specific. The K2 is MK-4, which clears the body quickly; for a once-daily habit, MK-7 stays around longer and is the more efficient choice, so the K2 here is working harder than it needs to. The metered dropper, while flexible, is slower and fiddlier than a fixed softgel and easy to miscount. And the whole premise of adding K2 to D3, while physiologically reasonable, is not a proven requirement for healthy people. None of that makes it a weak product — it makes it a clean, honest, well-certified liquid whose two real trade-offs are the K2 form and the dropper.
A consistent summary of formula, transparency, value and experience. Not a medical rating.
Scores follow our published 100-point methodology, applied identically to every product. View the scoring methodology.
May suit you if
- You specifically want vitamin D paired with K2 in one product, and you want a sensible 1,000 IU maintenance dose rather than a deficiency-correction megadose
- You prefer drops to pills, or you want to adjust your dose up or down without buying a different product — the liquid format is built for that
- You want a fully disclosed, vegetarian, third-party label-verified formula at the lowest per-serving cost, and you do not mind that the certification is NSF Contents Certified rather than NSF Certified for Sport
Skip it if
- You take your supplement once a day and want the most efficient K2 — the longer-acting MK-7 suits a once-daily habit better than the MK-4 used here
- You want the least-effort dosing possible — counting drops from a metered dropper is slower and fiddlier than swallowing a fixed softgel
- You only want plain vitamin D and see no reason to pay for the K2 — a cheaper D3-only product covers that, since the pairing is reasonable but not a proven necessity for healthy people
Plain Google search link — not an affiliate link. The Ingredient Report earns nothing if you purchase this product.
Key findings
Product specifications
| Format | Liquid drops in MCT oil; 2 drops per serving, taken straight or in water or food |
|---|---|
| Price (checked July 21, 2026) | ~$34 (1 fl oz bottle) |
| Cost per serving | ~$0.06 (~600 2-drop servings per bottle) |
| Vitamin D | 1,000 IU (25 mcg) as D3 — cholecalciferol — per 2-drop serving |
| Vitamin K2 | 200 mcg as MK-4 per 2-drop serving |
| K2 form note | MK-4 has a short half-life; MK-7 is more efficient for once-daily use |
| Base | MCT oil — suits a fat-soluble vitamin |
| Vegetarian | Yes — no gelatin |
| Certification | NSF Contents Certified (label accuracy & purity) — NOT NSF Certified for Sport |
The formula: D3 with K2, disclosed and sensibly dosed
On the fundamentals, this is a formula our vitamin D rubric rewards. It uses D3 (cholecalciferol), the more effective form of vitamin D, at 1,000 IU — a sensible daily maintenance dose that sits comfortably inside the 4,000 IU tolerable upper limit, rather than the 5,000 IU deficiency-correction doses that belong under a doctor’s guidance. It suspends both nutrients in MCT oil, which is appropriate for a fat-soluble vitamin, it prints every amount with no proprietary blend, and it is vegetarian with no gelatin. The K2 is a meaningful 200 mcg per 2-drop serving. Formula 20/25, transparency 18/20.
The deduction sits in the details of the K2 rather than the dose of the D3. The K2 here is MK-4, which has a short half-life — it clears the body relatively quickly, so for a supplement taken once a day the longer-acting MK-7 is the more efficient way to keep K2 available through the day. And a step back: pairing K2 with D3 is physiologically reasonable — the two vitamins interact in how the body handles calcium — but it is not a proven necessity for healthy people, so part of what you are buying is a combination you may not strictly need. That is an honest caveat, not a fault in the labeling.
The testing column
The certification here is real, and it is worth naming precisely because listings get it wrong. Thorne Vitamin D + K2 Liquid is NSF Contents Certified — an independent program that verifies the product actually contains what the label says, in the amounts stated, and screens for contaminants. That is a genuine label-accuracy and purity credential, and it is the main reason testing scores 15/20.
What it is not is NSF Certified for Sport. Those are different programs: Certified for Sport adds batch-level screening for banned substances aimed at competitive athletes, and this product does not carry it. Some retail listings conflate the two and describe this product as “NSF Certified for Sport” — it is not, and we state the correct program plainly. To be clear about what we have and haven’t checked: we photographed the label and verified the forms, the D3 and K2 amounts and the certification on it as of July 21, 2026. No safety or quality red flags surfaced in our review.
What it’s like to take
We have not yet run our own long-term trial — we photographed the label, and our hands-on testing is still pending, which we’d rather say plainly than pretend otherwise. What we can report on the format: the real advantage of the drops is flexibility. Two drops give you the standard 1,000 IU D3 and 200 mcg K2, but you can add them to water or food, take them straight, or adjust up or down without buying a different product. The MCT-oil base is neutral and mixes easily.
The recurring practical downside is the dropper itself: counting drops from a metered dropper is slow and a little tricky to get exactly right, and it is harder to be precise than simply swallowing a fixed softgel. For most people that is a minor daily friction rather than a dealbreaker, but if effortless, identical dosing is what you want, a softgel is easier. Experience 8/10, and we’ll update it once our own trial is done.
The math: excellent value per drop
This is a quiet win for the product. A 1 fl oz bottle runs about $34 and holds roughly 600 2-drop servings — about $0.06 a serving, which is excellent value despite the sticker looking higher than a bottle of generic softgels. For context, the plain D3 softgels in our comparison run roughly $0.04–$0.15 a serving without any K2, so getting D3 and K2 for about six cents a day is genuinely cheap for a combination product. And because the drops are dose-flexible, a single bottle stretches further still if you take a smaller amount. Value 12/15 — held just short of the top of the band by the MK-4 K2 form rather than by price.
Returns and where to buy
Widely available through major retailers and Thorne’s own channels rather than a subscription-first model, which spares you the usual auto-ship friction. Because it is a liquid dropper bottle rather than a sealed softgel bottle, the practical advice is ordinary care: keep it upright, capped and out of heat and direct light so the oil stays fresh, and use the dropper cleanly. No safety or quality red flags surfaced in our review, and the NSF Contents Certified seal is a point in its favor (checked July 21, 2026).
What customers report
We read customer feedback across the major platforms and summarize the recurring themes. We don’t republish other platforms’ reviews — check the live sources yourself:
Retail & DTC reviews
Broadly positive
Long-running high ratings; praise centers on the clean formula, the vegetarian liquid format and the flexible dosing — criticism centers on the fiddly dropper and counting drops precisely.
View live reviews →Certification & testing
NSF Contents Certified
Carries a genuine NSF Contents Certified label-accuracy and purity mark — but not NSF Certified for Sport, a point some listings get wrong, as of July 21, 2026.
Check the certification →Dietitian & expert coverage
Favorable with a form caveat
Dietitians tend to like the sensible D3 dose, the clear labeling and the liquid flexibility while noting MK-4’s shorter half-life versus MK-7 and that D3-plus-K2 is optional for healthy people — the same split this review scores.
Search expert reviews →We don't fact-check or verify individual customer reviews — reviewers' opinions and experiences are their own, and we never treat them as evidence that a product works or doesn't. We read feedback at scale, report recurring themes, and link the live sources.
Every factual claim on this page that is ours carries a checked date and a source. Spot an error? Tell us — corrections run under our corrections policy.
Reader reports · 0 so far
Share your experienceRight of reply: Thorne is welcome to respond to this review on the record — particularly on the choice of MK-4 over the longer-acting MK-7 for a once-daily supplement. Contact our editorial team — responses are published unedited alongside this review.
What to buy instead
If you do not actually need the K2, plain vitamin D is cheaper and simpler, and two disclosed, well-tested D3 softgels out-score this one on our rubric: Nature Made Vitamin D3 (87/100) is our best overall and best value, USP Verified at a sensible 2,000 IU, and NOW Vitamin D-3 (84/100) is the cheapest way to get a plain 2,000 IU dose — both are D3-only, with no K2. If you specifically want the D3-plus-K2 combination with the longer-acting MK-7 form, Sports Research Vitamin D3 + K2 (69/100) uses MK-7 and is vegan — but its 5,000 IU of D3 exceeds the 4,000 IU tolerable upper limit and is really a deficiency-correction dose for use under guidance, which is why it scores lower. The full picture, scored side by side, is in our vitamin D roundup, and the form question — D3 versus D2, and how much to take — is covered in our vitamin D3 ingredient guide. Where Thorne still earns its spot is being the sensible-dose combo in a flexible liquid: if you want D3 with K2 at 1,000 IU in drops, it is the honest pick. And to be plain: Earth Energy, the independently operated brand under common ownership with this site, makes no vitamin D product, so there is no in-house alternative to recommend here.
Final assessment
Thorne Vitamin D + K2 Liquid is the reassuring kind of Acceptable: a clean, fully disclosed, sensibly dosed vitamin D and K2 in a flexible liquid format, third-party verified for label accuracy, vegetarian, and cheap by the serving. It uses D3 at a maintenance 1,000 IU well inside the upper limit, pairs it with 200 mcg of K2 in an MCT-oil base, skips the proprietary blend, and costs about $0.06 a serving from a roughly 600-serving bottle. 81/100 — Acceptable, and our D3-plus-K2 and liquid pick — because the K2 is the shorter-acting MK-4 rather than the more efficient MK-7 for once-daily use, the metered dropper is fiddly to count exactly, and pairing K2 with D3 is reasonable but not a proven necessity for healthy people. None of that makes it a poor buy; it makes it a well-made combo whose trade-offs are the K2 form and the format. If you want vitamin D with K2 in dose-flexible drops, it is a fair pick — and if you take medications, especially blood thinners, or have a health condition, run any new daily vitamin D or K2 supplement past your doctor first.
Frequently asked questions
How much vitamin D and K2 is in Thorne Vitamin D + K2 Liquid?
A 2-drop serving delivers 1,000 IU (25 mcg) of vitamin D3, as cholecalciferol, plus 200 mcg of vitamin K2 as MK-4, suspended in MCT oil. The 1,000 IU is a sensible daily maintenance dose that sits well inside the 4,000 IU tolerable upper limit, and everything is printed plainly with no proprietary blend. It scores 81/100.
Is Thorne Vitamin D + K2 Liquid NSF Certified for Sport?
No — and this is a common mistake in listings. It is NSF Contents Certified, which is a genuine label-accuracy and purity program that verifies what the label claims is in the bottle and screens for contaminants. It is not NSF Certified for Sport, which is a separate program that adds banned-substance screening for competitive athletes. We state the correct program plainly.
Is MK-4 or MK-7 the better form of K2?
For a once-daily supplement, MK-7 is the more efficient form because it has a longer half-life and stays available in the body through the day. Thorne’s liquid uses MK-4, which works but clears faster. That is one of the honest reasons this product scores 81 rather than higher — and pairing K2 with D3 at all, while physiologically reasonable, is not a proven necessity for healthy people.
How much does Thorne Vitamin D + K2 Liquid cost per serving?
Checked July 21, 2026: about $34 for a 1 fl oz bottle, which holds roughly 600 2-drop servings — about $0.06 a serving. That is excellent value for a combined D3-plus-K2 product, and because the drops are dose-flexible a single bottle can stretch further still.
The Label Brief — free weekly report
The D3-plus-K2 liquid, honestly scored. Want next week’s label math first?
Every week we put one supplement label, one price claim and one viral promise under the same microscope. One five-minute email. No hype, no sponsored scores.
Get The Label Brief free →How we scored this product
Every product is scored with the same public 100-point methodology: formula and ingredient quality (25%), dosage and label transparency (20%), testing and manufacturing transparency (20%), value (15%), product experience (10%) and brand and customer experience (10%). Commercial relationships never add points. Read the full methodology.
Sources
- Thorne Vitamin D + K2 Liquid — official product, ingredient and pricing pages (1,000 IU D3 as cholecalciferol plus 200 mcg K2 as MK-4 per 2-drop serving; MCT-oil base; vegetarian, no gelatin; ~600 servings per 1 fl oz bottle; NSF Contents Certified). Checked July 21, 2026. thorne.com
- The Ingredient Report — vitamin D category comparison and scored reviews of Nature Made Vitamin D3 (87/100), NOW Vitamin D-3 (84/100), NatureWise Vitamin D3 (76/100), Nordic Naturals Vitamin D3 (75/100) and Sports Research Vitamin D3 + K2 (69/100), plus the vitamin D3 ingredient guide. Checked July 21, 2026.
- NIH Office of Dietary Supplements — vitamin D fact sheet establishing D3 (cholecalciferol) as the more effective form, the 4,000 IU (100 mcg) tolerable upper limit, and sensible daily maintenance dosing. Accessed July 21, 2026.
- NSF — Contents Certified program documentation distinguishing label-accuracy and purity certification from the separate NSF Certified for Sport banned-substance program. Accessed July 21, 2026.
- Retailer and dietitian coverage (ratings, format and dropper themes; MK-4 versus MK-7 discussion; linked live, not republished). Accessed July 21, 2026.
Update history
- July 21, 2026 — Report first published. Forms, D3 and K2 doses, certification and pricing checked this date; label photographed, hands-on trial pending. We re-score on the record if Thorne changes the K2 form to MK-7, alters the doses, or its pricing changes materially.
Content is for informational purposes only and is not medical advice. Talk with your healthcare provider before starting a daily vitamin D or K2 supplement, especially if you take medications such as blood thinners or have a health condition. Medical disclaimer.