Thorne Vitamin D3/K2 Liquid

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Thorne Vitamin D3/K2 Liquid

Pharmaceutical-grade D3 + K2 (MK-4) liquid drops. NSF Certified.

Thorne Vitamin D3/K2 Liquid

★★★★☆4.9 / 5 rating
500 IUD3
100 mcgK2
Liquid dropsForm
NSFCert.
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Pharmaceutical-grade D3 + K2 (MK-4) liquid drops. NSF Certified.

What is Thorne Vitamin D3/K2 Liquid?

Thorne Vitamin D3/K2 Liquid is part of our editor-vetted catalog of premium supplements. Our research team reviews each formula’s third-party testing, clinical research, and value to bring you transparent, evidence-based recommendations.

At a Glance

  • D3: 500 IU
  • K2: 100 mcg
  • Form: Liquid drops
  • Cert.: NSF

How We Researched This Product

Our editorial team evaluates every product against criteria including: ingredient quality and bioavailability, third-party testing (USP, NSF, ConsumerLab), dosage compared to clinical research, brand reputation and manufacturing standards, value per serving, and customer feedback patterns.

Where to Buy

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⚡ Quick Answer

Thorne Vitamin D3/K2 Liquid

Click any of the price-comparison buttons above to check current pricing at our verified retail partners. As an Amazon Associate we earn from qualifying purchases.

Important Notes

Educational content — not medical advice. Consult a qualified healthcare provider before adding any supplement to your routine, especially if you take prescription medication or have a medical condition.

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Scientific References
  • 1Holick MF, et al. (2011). Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. PMID 21646368
  • 2Pilz S, et al. (2011). Effect of vitamin D supplementation on testosterone levels in men. Horm Metab Res. PMID 21154195
  • 3Martineau AR, et al. (2017). Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis. BMJ. PMID 28202713
  • 4Autier P, et al. (2014). Vitamin D status and ill health: a systematic review. Lancet Diabetes Endocrinol. PMID 24622671

All studies are peer-reviewed and sourced from PubMed/NCBI. This article is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before starting any supplement regimen.

❓Frequently Asked Questions
For most adults with suspected deficiency: 2,000–4,000 IU D3 daily is safe and effective. The Endocrine Society recommends 1,500–2,000 IU for adults for bone health. For deficiency correction (25-OH level <20 ng/mL), short-term doses of 4,000–10,000 IU under medical supervision are used. Get your 25-OH level tested to optimize your dose.
Fatigue, bone and muscle aches, frequent illness, depression (particularly seasonal), hair loss, and slow wound healing are the most common. However, most people with deficiency have no obvious symptoms until tested. The only definitive test is a 25-hydroxyvitamin D blood test (25-OH D). Optimal range is 40–60 ng/mL (100–150 nmol/L).
Always D3 (cholecalciferol) — it's 87% more potent at raising and maintaining 25-OH levels compared to D2 (ergocalciferol). D3 is the form your skin makes from sunlight and the form found in fatty fish. D2 is derived from plants/fungi and is less bioavailable. Most prescriptions use D2 for historical reasons; over-the-counter D3 is superior.
Not strictly necessary for vitamin D's immune, muscle, and mood benefits. However, K2 (MK-7 form) works synergistically with D3: it activates osteocalcin (which directs calcium into bones) and matrix GLA protein (which prevents calcium from depositing in arteries). For cardiovascular safety at higher D3 doses (4,000+ IU), adding K2 (90–200mcg MK-7) is recommended.
Only in small amounts. Salmon provides ~450 IU per 3oz, canned tuna ~150 IU, egg yolks ~41 IU, and fortified milk ~120 IU per cup. To reach 2,000 IU from food alone, you'd need to eat 4–5 servings of salmon daily. Sunlight (arms/legs exposed for 15–30 minutes, 10am–3pm, without sunscreen) can produce 10,000–25,000 IU — but only in the right season, latitude, and skin type.