Vitamin D + K2, 1 fl oz (30 ml)
by Thorne
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Thorne's D3 + K2 liquid delivers 1,000 IU cholecalciferol and 200 mcg K2 as MK-4 per two drops, suspended in MCT oil for fat-soluble absorption. Best for People with confirmed vitamin D deficiency who need flexible, dose-adjustable supplementation and Those who cannot or will not swallow capsules — several reviewers use it for young children.
According to the AIScored 0–100 scoring system, Vitamin D + K2, 1 fl oz (30 ml) by Thorne scores 78.0/100, ranking #21 out of 35 products in Vitamin D (2026). Strongest category: Side Effects (91.0/100). Weakest: Certifications (35.0/100).
Is Vitamin D + K2, 1 fl oz (30 ml) worth buying?
“Thorne's liquid Vitamin D3 and K2 scores 87/100, and the real advantage is the flexibility to adjust your dose drop by drop if you're correcting a deficiency or following seasonal needs. Multiple reviewers have confirmed improved blood-level readings after using it, thanks in part to the K2 component directing calcium to your bones rather than soft tissues.”
What Do Reviewers Say About Vitamin D + K2, 1 fl oz (30 ml)?
Sample excerpts from currently available source material used in this product analysis.
"Excellent quality, great formula!. Thorne is such a trustworthy brand — their products are always top quality. I really like this Vitamin D + K2, the dosage is great and well balanced. I personally take a higher dose because I have a defici..."
"This is the best vitamin D!. The only one that has raised my vitamin D levels to the desired level, which was previously deficient! Which speaks volumes to the quality of the ingredients! I've tried a variety of brands before, but Thorne ha..."
"Thorne, Vitamin D with Vitamin K2, 25 mcg (1000 IU), Liquid. This supplement from Thorne is one of the most convenient forms of vitamin D, as it comes in a liquid with a dropper, which makes it easy to dose and add to food or drinks. The co..."
"Easy to quality and effective. I hardly go out in the sun do to late work hours indoors, i end up having Vitamin D deficiency, and been looking for an alternative to pills , i like the ingredient it has D and K with only 2 drops in my coffe..."
"Super!. Thorne Vitamin D + K2 is my favorite among vitamin supplements! 🌞 I really like the convenient liquid dosage — just two drops per day are enough to get optimal support for vitamin D levels along with vitamin K2 for better calcium ab..."
How does Vitamin D + K2, 1 fl oz (30 ml) score?
Detailed score breakdown and key findings from our analysis of 50 reviews across 1 source.
Pros
- +Liquid dropper allows precise, adjustable dosing — easily scaled up for deficiency correction or down for maintenance without cutting pills
- +MCT oil carrier supports fat-soluble vitamin absorption without requiring a fatty meal alongside
- +30ml bottle delivers approximately 600 two-drop servings — one bottle lasts many months even at higher daily doses
- +Neutral taste with no smell or fishy aftertaste — reviewers consistently report it disappears into food or drinks
- +Minimal formula: D3, MK-4, MCT oil, mixed tocopherols — no fillers, artificial colours, or unnecessary additives
Cons
- -Dropper dispenses slowly and individual drops are difficult to count accurately unless taken directly onto the tongue
- -1,000 IU per two drops is a modest serving — correcting a confirmed deficiency typically requires multiple servings daily
- -K2 as MK-4 has a shorter biological half-life than MK-7; sporadic or inconsistent use limits its effectiveness
- -No third-party testing confirmed per product specs
Best For
Watch Out
- !Dropper mechanism is slow — count drops carefully, or dispense onto a spoon first for accuracy
- !At higher therapeutic doses (6+ drops), total daily K2 intake rises significantly; worth monitoring if you take other K2 sources
- !MK-4 requires consistent daily use to maintain steady tissue levels — unlike MK-7, skipping days has a more pronounced impact
What is Vitamin D + K2, 1 fl oz (30 ml)?
Vitamin D + K2, 1 fl oz (30 ml) is a vitamin d product by Thorne, scoring 78.0/100 on AIScored.
- • Thorne Vitamin D + K2 Liquid combines vitamin D3 (1,000 IU) and vitamin K2 as MK4 (200 mcg) in a convenient liquid drop format, NSF Certified.
- • The two nutrients work better together than either does alone, supporting bone health, cardiovascular health, and normal immune function.
- • Each serving is two drops, taken one to three times daily — invert the bottle to dispense individual drops.
- • The formula can be added to food or mixed into drinks and does not need to be refrigerated.
- • Other ingredients are medium chain triglyceride oil and mixed tocopherols.
- • Manufactured in the UK using UK and imported ingredients.
- • If pregnant, consult your healthcare practitioner before use.
Is Vitamin D + K2, 1 fl oz (30 ml) Independently Tested?
No Third-Party Testing Visible
We could not find evidence of independent third-party testing for this product. This doesn't mean it's unsafe, but independent verification provides additional assurance.
How We Score Supplements
Our methodology analyses review data, ingredient science, and product information, then scores each product on a 0-100 scale across evidence-based categories:
Effectiveness
How well the product delivers its claimed benefits, based on reviews and ingredient evidence.
Ingredient Quality
Bioavailable forms, clinically effective dosages, clean label, minimal fillers.
Value for Money
Price relative to ingredient quality, dosage count, and effectiveness.
Side Effects Profile
Higher score = fewer side effects. 100 means virtually no adverse reactions reported.
Certifications & Testing
Third-party lab testing, GMP certification, and independent quality verification.
Overall Score
Weighted combination of all factors. Our bottom-line recommendation.
Price History (90 days)
Quick Facts
- Vegan
- No
Frequently Asked Questions
Is Vitamin D + K2, 1 fl oz (30 ml) worth buying in 2026? ▼
What is the best price for Vitamin D + K2, 1 fl oz (30 ml) in the UK? ▼
What are the pros and cons of Vitamin D + K2, 1 fl oz (30 ml)? ▼
Is Vitamin D + K2, 1 fl oz (30 ml) third-party tested? ▼
What the Data Says About Vitamin D
Why do 97% of UK vitamin D supplements lack third-party certification?
Only 1 out of 35 vitamin D products we scored has independent certification. That's 97% without any third-party verification of purity, potency, or label accuracy.
This is worse than most supplement categories. The reason is simple: UK law doesn't require it, and testing costs money. Most vitamin D brands sell on price alone, especially in the D3-only space where the raw ingredient is cheap. Certification adds cost that budget brands won't absorb.
What does this mean for you? Without third-party testing, you're trusting the manufacturer's label claims. A 2021 study in Nutrients found that vitamin D supplements varied from 52% to 135% of their labelled dose. That's a problem if you're relying on a specific daily intake.
Among the 35 products we scored, the top performers are all from brands with strong manufacturing track records: NOW Foods D3 5000 IU and Thorne Vitamin D + K2 both score 87/100 overall. Thorne holds the highest certification score in the category at 85/100. If independent testing matters to you, that's the product to look at.
Do you need vitamin K2 with high-dose vitamin D?
Probably yes at high doses, and our data backs the pairing. Thorne Vitamin D + K2 Liquid is the only D3+K2 combo product in our 35-product database that scores 87/100 overall, matching the top-ranked D3-only options from NOW Foods. It also holds the highest certification score in the category at 85/100.
Here's the science behind it. Vitamin D increases calcium absorption from food. Vitamin K2 activates proteins that direct that calcium into bones and teeth, keeping it out of your arteries and soft tissue. At standard doses (1000-2000 IU daily), most people get enough K2 from diet to handle the extra calcium. At 4000-5000 IU daily, the calcium load increases enough that K2 becomes a more serious consideration.
The Endocrine Society doesn't yet include K2 in its vitamin D guidelines. But a growing body of research, including a 2019 meta-analysis in International Journal of Molecular Sciences, shows the D3+K2 combination improves bone mineral density more than D3 alone.
If you eat K2-rich foods regularly (natto, hard cheese, egg yolks, chicken liver), a standalone D3 product like NOW Foods D3 5000 IU 360 Softgels (87/100) is a solid choice. If your diet is low in K2, or you're taking 4000+ IU of D3 daily, Thorne D + K2 covers both bases in one product.
Disclaimer: AIScored provides research-backed summaries based on publicly available reviews and product information. This is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Affiliate links may earn us a commission at no extra cost to you.
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