Let me start with this: At K3 Nutriments, we don’t add anything to a formula unless it serves a real purpose. That’s not marketing — that’s the standard we hold ourselves to with every ingredient.
The decision to combine vitamin K2 and K3 didn’t come from a trend or a guess. It came after carefully reviewing the research, examining formulation studies, and speaking with experts on nutrient absorption and delivery. We wanted to be sure that if we were going to combine these two forms, it would be done right — and for the right reasons.
Most people know a little about vitamin K2 — it’s gained traction for bone and heart health — but vitamin K3? That one raises eyebrows. And frankly, it should. There’s a lot of confusion around it, and a lot of noise. So let’s clear it up.
Here’s what we’ve learned, what we’ve seen, and why K3 Nutriments decided to use both K2 and K3 — carefully and intentionally — in our formulation.
Understanding the Vitamin K Family
Vitamin K isn’t just one compound. It’s a family of fat-soluble vitamins, and they each play different roles. Most people are familiar with K1 — the kind found in leafy greens — but it’s K2 and K3 that deserve a closer look when it comes to metabolic function and long-term wellness.
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Vitamin K1 (phylloquinone) is found in spinach, kale, and other greens. It helps blood clot properly, which is crucial but only one piece of the puzzle.
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Vitamin K2 (menaquinones) comes from fermented foods, cheeses, and organ meats. It helps your body transport calcium to where it should go — into your bones and teeth — and keep it out of where it doesn’t belong, like your arteries.
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Vitamin K3 (menadione) is synthetic. It’s not found in nature. And while that sounds like a red flag, it’s actually more nuanced than that.
K2 gets all the attention for good reason — it’s critical for bone strength, cardiovascular flexibility, and nutrient synergy. But if you stop there, you may be missing part of the equation.
What K2 Does (and Why It’s Non-Negotiable)
K2’s impact on bone and heart health is backed by solid data. It activates proteins like osteocalcin and matrix GLA-protein — both vital for keeping calcium in your bones and out of your soft tissues.
What this means practically is:
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Stronger bones that can better retain density over time
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Arteries that stay clearer and more flexible
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Synergistic benefits when taken with vitamin D3
We use the MK-7 form of K2 in our Vitamin K2+D3 Complex because it has the longest half-life and highest bioavailability. It stays in the bloodstream longer, meaning it can keep doing its job hours after ingestion.
This is not the kind of ingredient you throw in for marketing. It’s fundamental. That’s why it’s front and center in our formulation.
What About K3? Isn’t That… Bad?
K3 gets a bad rap, and some of that is justified. It’s not found in food. It’s synthetic. And at high doses — or in unstable forms — it can stress the liver. That’s a concern, and we take it seriously.
But there’s another side to this story.
K3 is more water-soluble than K2. That means it can be absorbed in different areas of the digestive tract, potentially offering more complete coverage in people who have fat absorption issues — something surprisingly common in the real world.
In clinical nutrition settings, K3 has been used to support vitamin K status where food absorption isn’t reliable. And when it’s stabilized and micro-dosed properly, it can be safe, effective, and complementary to K2.
Why We Chose to Combine K2 and K3 (and How We Did It Right)
We didn’t include K3 just because it looked good on a label. We chose it because the research supported it — and only when it could be formulated safely and effectively.
Here’s why:
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K3 may help broaden absorption pathways in the gut
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It may offer support for those with impaired fat digestion
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At very low doses, it may reinforce the bioactivity of MK-7 without overwhelming the liver
We use:
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Micro-dosed, stabilized menadione
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No raw K3
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No unbound synthetics
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And always with full label transparency
“We didn’t add K3 to make the label look smarter — we added it because some people genuinely benefit from it. That’s the kind of formulation decision we make here.”
— Doug Krussel, Founder of K3 Nutriments
The truth is, K2 and K3 can work better together — but only in the right ratios, and only when formulation is done with intent.
What This Means for Absorption
K vitamins don’t work in a vacuum. Your digestion, gut lining, bile production, and even microbiome affect how well they’re absorbed.
This is especially important for people who:
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Follow very low-fat diets
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Have gallbladder issues
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Take medications that interfere with fat absorption
That’s where the synergy of K2 and K3 may shine. K2 offers long-lasting fat-soluble delivery, and K3 (when formulated properly) adds a layer of accessibility for different pathways.
If your digestion or liver function is impaired, nutrients like K2 and K3 may not absorb optimally — which is why compounds like Betaine HCL and TMG can play a valuable supporting role.
Final Thoughts
Are K2 and K3 better together?
When dosed irresponsibly? No.
When used without stabilizers? No.
But when carefully combined — at micro-dose levels, stabilized, and in synergy with other fat-soluble vitamins like D3 — the answer becomes: very possibly, yes.
That’s the formulation you’ll find in our Vitamin K2+D3 Complex. And that’s the kind of decision we make at K3 — not based on trends, but on real science and formulation integrity.
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Doug Krussel
Founder, K3 Nutriments