- ✓5,000 IU Vitamin D3 — gets 93% of deficient adults to serum sufficiency. At 2,000 IU (what most brands use), only 43% reach it.
- ✓180mcg MenaQ7® K2 (MK-7) — the exact dose from the landmark 3-year Knapen RCT showing improved bone density and reduced arterial stiffness. Most brands use 50–100mcg.
- ✓200mg Magnesium Glycinate cofactor — both D3-activating enzymes (hepatic and renal) are magnesium-dependent. Without it, D3 stays in storage form regardless of dose.
- ✓Zinc (15mg) + Boron (3mg) — Zinc activates Vitamin D Receptors in target cells. Boron extends D3 half-life by 25–40%. No competitor includes either.
- ✓The only formula combining all 5 clinical actives at the doses the research actually used — in an MCT oil base for superior fat-soluble absorption.
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Prime D3+K2 contains five clinically-dosed actives, each selected to close a specific gap in the D3 activation chain:
- D3 — 5,000 IU — gets 93% of deficient adults to serum sufficiency
- MenaQ7® K2 — 180mcg — directs D3-absorbed calcium to bones, away from arteries
- Magnesium Glycinate — 200mg — required cofactor for both D3-activating enzymes
- Zinc — 15mg — enables Vitamin D Receptor (VDR) expression in target cells
- Boron — 3mg — extends D3 half-life 25–40% by inhibiting its breakdown enzyme
See the full comparison table →
Most D3+K2 products get two things wrong — and most people never find out.
First, the K2 dose. The study showing bone density improvement and reduced arterial stiffness used 180mcg of MenaQ7® K2 for three years. Most brands deliver 50–100mcg of generic MK-7. That's 28–55% of the clinical dose — and generic MK-7 doesn't have the published human trial data that MenaQ7® does.
See the full comparison →
Based on clinical data and customer reports:
- Weeks 1–4: D3 serum levels begin rising. Energy and immune symptoms improve as D3 reaches functional range
- Month 1–2: Calcium metabolism normalizes. K2 begins directing calcium away from soft tissue
- Month 3–6: Bone density and arterial protection improvements become measurable — consistent with the clinical trial timeline
IMPORTANT D3 and K2 work at the cellular level over time. The landmark bone density study ran for 3 years. Results compound — the longer you take it at clinical doses, the more complete the effect.
K2 activates two proteins that D3 alone cannot: osteocalcin (which anchors calcium into bone) and Matrix Gla Protein (which prevents calcium from depositing in arteries).
Both proteins are dose-dependent. The 2013 Knapen RCT that showed reduced arterial stiffness used 180mcg of MenaQ7® for 3 years. Brands using 50mcg are delivering 28% of that dose. The mechanism can't fully activate at sub-clinical amounts.
- Ships in 1–2 business days from our warehouse
- Most orders arrive in 3–6 business days
- Free shipping on all orders
- 90-day money-back guarantee — full refund, no questions, no hassle
If you don't notice a difference in energy, immunity, or overall wellbeing within 90 days, we'll refund every penny. You don't need to send the bottle back.
Yes. Prime D3+K2 is third-party tested, GMP-certified, made in the USA, and free of heavy metals, gluten, soy, and artificial fillers. The MCT oil base is specifically chosen for superior fat-soluble vitamin absorption.
NOTE Vitamin K2 can interact with anticoagulant medications like warfarin or Coumadin. If you take blood thinners, consult your physician before use. For all other medications, separate by 2 hours as a general precaution.
42% of Americans are Vitamin D deficient. Most of them are already taking a D3 supplement. So why aren't their levels improving — and why are so many of them still ending up with calcification concerns?
D3 increases calcium absorption. That's the whole point. But calcium absorbed into the blood needs directions. Without K2, it doesn't get any.
But that's not even the first problem.
Before D3 can do anything, it has to be converted into its active form — calcitriol — through two enzyme reactions, one in the liver, one in the kidneys. Both enzymes are magnesium-dependent. If you're magnesium deficient (48% of Americans are), your D3 stalls in storage form regardless of how much you take. The supplement is working. The activation chain is broken.
Then there's the calcium paradox. D3 pulls calcium into your blood. Without 180mcg of MenaQ7® K2 activating Matrix Gla Protein and osteocalcin, that calcium has no instructions. It doesn't go to your bones. It deposits in your arteries. The supplement you're taking to support bone health may be doing the opposite — because it's missing the ingredient that tells calcium where to go.
Most brands cite the Knapen RCT. Most deliver 50mcg of K2. The study used 180mcg. That gap is not a footnote. It's the difference between results and none.
Prime D3+K2 uses five separate actives, each one selected for a specific gap in the D3 activation chain.
The D3 (5,000 IU) gets 93% of deficient adults to serum sufficiency — versus 43% at the 2,000 IU most brands use. The MenaQ7® K2 (180mcg) is the exact dose from the 3-year Knapen RCT showing bone density improvement and reduced arterial stiffness. The Magnesium Glycinate (200mg) provides the cofactor every D3-activating enzyme requires. The Zinc (15mg) enables Vitamin D Receptor expression in target cells. The Boron (3mg) inhibits the enzyme that breaks D3 down, extending its half-life by 25–40%.
Most D3+K2 products use two ingredients and call it a day. This one uses five, and every dose matches what the researchers actually used.
Cholecalciferol
K2 MK-7
Glycinate
Bisglycinate
Glycinate
⚠️ WARNING: The K2 in Prime D3+K2 is MenaQ7® — a patented, clinically studied form of Menaquinone-7 with one certified supplier in the world: NattoPharma, Norway. When their allocation runs out, we cannot switch to a generic source and maintain the formula's integrity.
Most brands use generic MK-7 sourced from bulk commodity suppliers. We don't. MenaQ7® is the only K2 form with published human clinical trials showing measurable bone density improvement and reduced arterial stiffness at 180mcg. There is no substitute.
This is not a marketing tactic...
Prime D3+K2 is one of the only consumer formulas using the full 180mcg clinical dose of MenaQ7®. At that dose, we burn through allocation faster than brands using 50–100mcg. When supply is constrained, we can't just produce more.
We currently have stock for approximately 2–3 weeks at current order volume. MenaQ7® lead times have stretched to 10–14 weeks due to increased demand across the category.
When we have it, we recommend stocking up. Many customers order 3–4 bottles for this reason.
Magnesium
I switched to Prime D3+K2 because of the magnesium cofactor angle. I read that the enzymes that convert D3 to its active form require magnesium, and I was almost certainly magnesium deficient too. That would explain why my D wasn't budging.
Eight weeks later: D levels at 61 ng/mL. My doctor asked what I changed. I explained the cofactor issue. She went quiet for a second and said "that actually makes sense." That was enough for me.
The Knapen study kept coming up — 180mcg of MenaQ7 K2 for 3 years showed measurable reduction in arterial stiffness. Every product I found was using 45 or 100mcg. Prime D3+K2 was the only one I found using the actual study dose.
Six months in, my follow-up scan showed no progression. My cardiologist said "whatever you're doing, keep doing it." He didn't ask what it was. I told him anyway. He looked it up right there in the office.
Someone in a health optimization group pointed out that D3 without magnesium is like having a key without a lock. The enzyme that converts it needs magnesium to work. I was probably deficient in both and fixing one without the other wasn't enough.
Four weeks on Prime D3+K2 and my afternoon energy is unrecognizable. I used to need a second coffee at 2PM just to get through the rest of the day. I haven't needed it once this month. My mood is steadier. I actually want to go outside after work instead of collapsing on the couch.
The magnesium-D3 connection is real and well-documented. The Vanderbilt-Ingram Cancer Center data showed magnesium supplementation alone increased the efficacy of D3 by 30%. Most pharmacists — myself included until recently — weren't telling patients this.
Prime D3+K2 is the first consumer product I've found that gets all three right: the D3 dose (5,000 IU), the K2 dose (180mcg MenaQ7®, not generic), and the magnesium cofactor. The zinc and boron additions are evidence-based too. I now recommend this to patients before anything else on the shelf.
I started researching K2 after reading that calcium supplements without K2 can actually increase calcification risk. D3 pulls calcium in. K2 tells it where to go. Without K2, the calcium I was taking wasn't going to my bones — it was going somewhere else.
Switched to Prime D3+K2 for 8 months. My most recent DEXA showed a 2.1% improvement in lumbar spine density. My doctor called it "statistically meaningful." I called it the first good news I've had from a bone scan in three years.
I know correlation isn't causation. But I also know D3 at adequate blood levels is one of the most well-documented immune regulators we have. The difference is I was finally taking enough of it, at the dose that actually gets most people to sufficiency.
2,000 IU was doing almost nothing for my levels. 5,000 IU with the magnesium cofactor was a different thing entirely. My doctor confirmed my D levels hit 58 ng/mL at my annual physical. First time I've ever been in the optimal range.
Switched to Prime D3+K2 four months ago. The difference I notice most is energy — specifically that I don't feel like I need to drag myself through the afternoon anymore. I didn't expect that from a D3 supplement. Turns out active vitamin D is involved in mitochondrial function. When it actually activates properly, it's different.
Also worth noting: the boron addition is something I've never seen in another D3+K2 product. I looked it up — it genuinely does inhibit the enzyme that breaks D3 down. It's not a marketing gimmick. This formula is built by people who read the actual studies.
