Despite being one of the most critical nutrients for long-term heart, bone, and metabolic health, Vitamin K2 remains largely un-mentioned in modern medicine. I’ve been taking K2 daily for over ten years, and the evidence backing its benefits just keeps getting stronger.
The Calcium Paradox: When Good Intentions Go Bad
Traditionally, the focus in health care has been solely on calcium and vitamin D for bone health. It turns out, though, that there’s more than meets the eye when it comes to preventing osteoporosis. Several studies (ref, ref, ref, ref) revealed a troubling pattern. For every 3 fractures prevented per 1,000 women receiving calcium supplements, there were twice as many heart attacks and strokes. In addition, calcium supplementation increases the risk of developing kidney stones (ref).
How could that be? Now, we understand that if you just supplement calcium, with or without vitamin D, the calcium can go anywhere and everywhere — not only the bones and teeth where you’d like for it to go, but also to the soft tissues, including blood vessels. Several decades prior, there was a clue that eventually led us to discover the missing factor.
Enter Weston Price and “Activator X”
In the early 1900s, a pioneering dentist named Weston A. Price traveled the world studying indigenous diets and health outcomes. He noticed that communities eating traditional, nutrient-dense foods had broad, healthy facial structures, straight teeth, and little chronic disease. In contrast, when these populations were later exposed to modern diets with sugars and refined grains, they suffered a plethora of ailments including dental caries (cavities), crowded teeth and facial structure, and increased heart disease.
He identified a mysterious compound he called “Activator X” — present in foods like high-vitamin butter oil — which seemed to protect against tooth decay, heart disease, and other ailments.
Decades later, researchers finally discovered what this elusive nutrient was: vitamin K2.
What Is Vitamin K2, and Why Do We Need It?
Vitamin K2 is part of the fat-soluble vitamin family (along with A, D, and E). Unlike vitamin K1, which helps with blood clotting and is found in leafy greens, K2 has a unique role: it acts as the director of calcium, pulling it out of your soft tissues and guiding it into your bones and teeth, where it belongs.
Vitamin K2 activates a protein called osteocalcin that directs calcium into the bones and the teeth. It also activates proteins (matrix Gla protein – MGP) that prevent calcium from infiltrating the blood vessels. Without enough K2, calcium can deplete from your bones/teeth and accumulate in your arteries, contributing to calcified plaque and cardiovascular disease — the very problem we saw in those calcium supplement trials.
Where Do You Get Vitamin K2?
Modern diets are severely lacking in K2 because we’ve moved away from traditional, fermented, and animal-based foods. The two main natural sources are:
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Grass-fed animal products (like cheeses, egg yolks, organ meats, and butter)
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Fermented foods — especially natto, a Japanese dish of fermented soybeans that’s high in a potent form of K2 called MK-7. Also sauerkraut and fermented cheeses.
Cheeses like Gouda, Emmental, and Bleu are rich in K2, particularly when made from grass-fed milk. Wild game and organ meats (especially liver pâté) are also excellent sources — but remember, K2 is fat-soluble, so you need to eat the fat.
The Forms of Vitamin K2: MK-4 vs. MK-7
There are several forms of K2, but the two most important are:
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MK-4: Found in animal products. It has a shorter half-life and is typically taken multiple times a day in supplement form.
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MK-7: Found in fermented foods like natto and most commonly used in supplements. It has a much longer half-life and can be taken once daily.
I personally use a full-spectrum supplement with multiple forms of K2, typically in an MCT oil base (avoid ones with low-quality, inflammatory base fats such as soybean oil or other seed oils).
Why Is Vitamin K2 So Important?
The benefits of K2 go far beyond bone health. Increasing evidence suggests that vitamin K2 plays a role throughout the body (ref):
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Cardiovascular health: Multiple studies show people with higher K2 intake have up to a 40% lower risk of heart disease and decreased all-cause mortality. K2 inhibits arterial calcification — something no other nutrient does as effectively. The Rotterdam Study (ref) demonstrated that individuals with the highest consumption of vitamin K2 had the lowest rates of heart disease, aortic calcification, and all-cause mortality.
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Bone health: K2 activates osteocalcin, a protein that binds calcium into the bone matrix, reducing fracture risk. Areas in Japan where natto is consumed have lower rates of hip fractures (ref).
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Dental health: Weston Price used high-vitamin butter oil rich in K2 to reverse tooth decay in children. K2 may be beneficial for dental health in terms of re-mineralization of the teeth and favorable effects on the saliva (ref).
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Metabolic health: Systematic reviews and meta-analyses in 2023 (ref) and 2025 (ref) found that MK-7 improves glucose control and reduces insulin resistance.
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Skin aging: K2 helps preserve skin elasticity and reduces wrinkle formation by preventing calcification of skin tissues.
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Brain health: Emerging evidence suggests K2 may support cognitive function and reduce the risk of neurodegeneration (ref, ref).
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Cancer protection: Early research hints at potential cancer-fighting properties in many types of cancers (ref, ref).
Seasonal Variations and Modern Deficiencies
Weston Price also observed that traditional communities experienced a natural dip in K2 intake during Winter when fresh grass (the basis of K2 production in animals) was scarce, associated with an increase in heart attack deaths, while a rise in K2 intake during the Summer was associated with fewer deaths. Modern research demonstrates this same seasonal phenomenon — a 2010 study (ref) found that arterial calcification is highest in Winter months, and lowest in Summer.
Our modern, industrialized food system has stripped away these ancestral sources of K2, leaving most people deficient unless they actively seek it out.
The Full Nutrient Team: K2, D3, A, and Magnesium
K2 works best when paired with vitamin D3, vitamin A, and magnesium. Vitamin D increases calcium absorption, but without K2, that calcium can go astray. Magnesium is also crucial in regulating calcium metabolism.
How Do You Know If You’re Deficient?
There’s no simple clinical test for vitamin K2 deficiency. Research labs can measure levels of uncarboxylated osteocalcin (a marker of deficiency), but these aren’t widely available.
Given the safety profile of K2, it’s wise to err on the side of supplementation — especially if you’re at risk for osteoporosis, cardiovascular disease, or insulin resistance.
Final Thoughts: Why You Haven’t Heard About This
If K2 is so powerful, why isn’t it front-page health news? Simple: there’s no big money in it. It’s a natural, affordable nutrient that you can get from food or inexpensive supplements. Without pharmaceutical backing, large-scale studies are slow to come, and media coverage is sparse.
Recommended supplement: Look for a product containing MK-7 and MK-4 (preferably in MCT oil, without seed oils or soybean oil). I personally use one from Innovix Labs [not an affiliate link], but there are several good options on the market.
