Equipment Reference

Thorne

Thorne Vitamin D/K2 Liquid

Combined D3 + K2 drops for calcium routing and bone health

4.8

(2,100 community reviews)

Thorne Vitamin D/K2 Liquid combines 1000 IU vitamin D3 with 200mcg MK-4 vitamin K2 per drop. Peter Attia and Rhonda Patrick's recommended pairing: D3 increases calcium absorption, K2 directs it to bones instead of arteries. Liquid format allows precise dosing.

Used by

Peter AttiaRhonda PatrickLongevity stack buildersBone health community

Typical price: $24 – $32 USD / 600 drops

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How It Works

Vitamin D3 increases intestinal calcium absorption and osteocalcin production. Vitamin K2 carboxylates osteocalcin (directing calcium to bone) and matrix Gla protein (preventing arterial calcification). Co-supplementation prevents the 'calcium paradox' of D3 alone.

D3 + K2 Synergy

D3 enhances calcium absorption; K2 activates osteocalcin and matrix Gla protein to route calcium correctly.

Liquid Dosing

Adjust drops based on blood panel results. 2–5 drops delivers 2000–5000 IU D3 + proportional K2.

MK-4 Form

200mcg MK-4 per drop. Shorter half-life than MK-7 but well-studied in Japanese clinical trials.

What You'll Experience

Baseline

Week 1

No acute effects. Start dosing based on current D3 levels or 2000 IU/day default.

Blood Panel

Month 2–3

Retest 25-OH vitamin D. Target 40–60 ng/mL. Adjust drops accordingly.

Long-term

Year 1+

Structural benefits for bone density and arterial health. Retest D3 annually.

Benefits

Calcium Routing

Moderate Evidence

K2 ensures D3-driven calcium absorption benefits bones, not arteries.

Bone Health

Moderate Evidence

Combined D3+K2 supports bone mineral density in clinical trials.

Flexible Dosing

Strong Evidence

Liquid drops allow precise IU adjustment based on blood panels.

Risks & Considerations

Warfarin Interaction

high risk

K2 opposes warfarin. Do NOT use without physician supervision if on blood thinners.

D3 Overdose

low risk

Monitor D3 levels. Toxicity rare below 10,000 IU/day but test annually.

Community Reviews

Synthesized consensus from Reddit, forums, and expert sources.

Reddit r/Supplements

Mostly Positive

Thorne D/K2 Liquid is the top recommendation for combined D3+K2. 'If you take D3, take K2.'

·Combined D3+K2 eliminates need for separate products
·Liquid format makes dose adjustment easy
·Test D3 levels and adjust drops to hit 40–60 ng/mL

View source

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Last updated: 2026-07-11 · Informational only. Not medical advice.