The Daily Foundation
Vitamin K2
Vitamin K2
MK-7
The vitamin most people have never heard of that their body cannot do without. Dosed at 75µg. Every serving.
75µg per serving · 12.5µg per capsule · 6 capsules daily
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Daily Dose Per Serving
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Half-Life of MK-7 vs 2hrs for MK-4
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Of Adults with Suboptimal K2 Status
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Key K2-Dependent Proteins Activated
What It Does
Three things. All proven.
Bone Density
K2 activates osteocalcin, a protein produced by bone-building cells that binds calcium into the bone matrix. Without adequate K2 to activate it, osteocalcin remains inactive and calcium cannot be effectively incorporated into bone regardless of how much calcium and vitamin D you consume.
Cardiovascular Protection
K2 activates Matrix Gla Protein, the most potent known inhibitor of arterial calcification. Without K2, MGP remains inactive and calcium deposits accumulate in arterial walls. This is the mechanism behind the consistent epidemiological finding that higher K2 intake is associated with reduced cardiovascular mortality.
Enhanced D3 Efficacy
Vitamin D3 dramatically increases calcium absorption from the gut. K2 determines where that calcium goes. Without K2, calcium absorbed under the influence of D3 has no reliable guidance system. The two nutrients are functionally interdependent and should always be taken together.
The Science
The vitamin most people have never heard of that their body cannot do without.
Vitamin K exists in two main forms with fundamentally different biological roles. Vitamin K1, phylloquinone, is found in green vegetables and is primarily involved in blood coagulation. Vitamin K2, menaquinone, is found in fermented foods and certain animal products and is primarily involved in calcium regulation, bone metabolism and cardiovascular protection. The two forms are not interchangeable. Adequate K1 intake for blood clotting says nothing about K2 status for calcium direction.
K2 itself exists in multiple subtypes classified by the length of their side chain. MK-4 is the form found in animal products. MK-7 is the form produced by bacterial fermentation, found most abundantly in natto, a Japanese fermented soybean food. The critical difference between MK-4 and MK-7 is their half-life in the body. MK-4 has a half-life of approximately 2 hours. MK-7 has a half-life of 72 hours. This means MK-7 reaches and maintains significantly higher tissue concentrations from a single daily dose, which is why MK-7 is the form supported by the most compelling modern research and the form used in this formula.
The mechanism through which K2 operates is the carboxylation of vitamin K-dependent proteins. These proteins require K2 as a cofactor to become biologically active. The two most clinically significant are osteocalcin, which directs calcium into bone, and Matrix Gla Protein, which inhibits calcium from depositing in soft tissues including arteries. Both are activated by K2 and inactive without it. The consequences of chronic K2 insufficiency therefore include simultaneously weaker bones and harder arteries, the opposite of what you want.
Why almost nobody gets enough K2 from food.
The primary dietary source of MK-7 is natto, a traditional Japanese food made from fermented soybeans. A single 100g serving of natto contains approximately 1,000µg of MK-7, which is extraordinary. It is also strongly flavoured, has a distinctive texture that most Westerners find difficult to eat, and is essentially absent from standard UK food culture. Regular natto consumption is not a realistic strategy for the vast majority of people in this country.
Other dietary sources of K2 include hard cheeses, egg yolks, chicken liver and certain fermented dairy products. These contain predominantly MK-4 rather than MK-7, and at considerably lower concentrations than natto. Estimated K2 intake in Western populations is typically 10 to 30µg per day, substantially below what research suggests is required to fully activate the K2-dependent protein system.
Unlike vitamin K1 deficiency, which produces obvious and rapidly dangerous coagulation problems, K2 deficiency is silent and slow. It manifests over years as progressively impaired calcium regulation, with consequences for bone density and arterial health that accumulate without obvious symptoms until the damage is already done. This is one of the reasons K2 remains so underappreciated despite its fundamental biological importance.
K2 deficiency has no obvious short-term symptoms. The consequences accumulate silently over years in bone and in arteries. This is why most people do not know they need it.
Unless you eat cheese daily, you are probably short.
Hard aged cheeses such as Gouda and Edam contain meaningful K2 in the MK-4 and MK-8 to MK-10 range, though not MK-7 in significant quantities. Regular consumption of fermented dairy products provides some K2, but the amounts available in a typical UK diet are consistently below the threshold required for full activation of K2-dependent proteins based on blood markers of K2 status.
Research measuring ucOC (uncarboxylated osteocalcin) and ucMGP (uncarboxylated Matrix Gla Protein) as functional markers of K2 status consistently shows that a majority of Western adults have elevated levels of these inactive proteins, indicating that their K2 intake is insufficient to fully activate them. This is a functional measurement of insufficiency rather than a dietary estimate, which makes it considerably more meaningful.
Functional markers of K2 status show that the majority of Western adults have insufficient K2 to fully activate their calcium-regulatory proteins. Diet alone is not closing this gap.
Why MK-7 and not MK-4? The chain length that changes everything.
The scientific literature on vitamin K2 moved decisively toward MK-7 over the past decade for one primary reason: pharmacokinetics. MK-4 is absorbed and metabolised rapidly, producing a peak in blood levels within hours that then falls back to baseline. MK-7 absorbs more slowly, reaches lower peak concentrations but maintains substantially higher tissue levels throughout a 24-hour period following a single dose. This sustained presence is what enables full carboxylation of K2-dependent proteins.
The key clinical trials establishing K2 benefits for bone and cardiovascular outcomes have used MK-7. The Rotterdam Study, which first established the epidemiological connection between K2 intake and reduced cardiovascular mortality, drew on dietary K2 assessment that reflected total K2 intake. The mechanistic work, however, and the controlled intervention trials have predominantly used MK-7 specifically because of its superior pharmacokinetic profile.
The 75µg MK-7 dose in this formula reflects the dose used in the most well-designed intervention trials. The MenaQ7 trial, which used 180µg MK-7 over three years, showed significant improvements in both bone density markers and arterial stiffness. 75µg is a daily maintenance dose for people not starting from a depleted baseline, which is appropriate in the context of a comprehensive daily supplement rather than a therapeutic correction.
MK-7 maintains active tissue levels for 72 hours from a single dose. MK-4 clears in 2. This is not a minor pharmacological difference. It is a fundamental one.
Anyone supplementing D3. Anyone concerned about bones or heart health. Most people.
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Anyone taking vitamin D3. This is the most important category. D3 increases calcium absorption significantly. Without K2 to direct that calcium, you are increasing the substrate for arterial calcification alongside the substrate for bone mineralisation. Taking D3 without K2 is an incomplete strategy.
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Anyone concerned about bone density. Postmenopausal women, older adults, athletes with high impact loading and anyone with a family history of osteoporosis. K2 is essential for the osteocalcin activation that drives calcium into bone matrix regardless of how much calcium and D3 is consumed.
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Anyone with cardiovascular risk factors. The epidemiological evidence linking higher K2 intake to reduced arterial calcification and cardiovascular mortality is among the most compelling nutritional epidemiology data available. The Rotterdam Study specifically found that high K2 intake was associated with a 50% reduction in aortic calcification.
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People eating Western diets with low fermented food intake. The dietary K2 gap in Western populations is significant and consistent across research. If you are not regularly eating fermented dairy, organ meats or natto, your K2 intake is almost certainly below the threshold for full protein activation.
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Anyone on a long-term supplement programme. K2 is the overlooked partner in almost every bone and cardiovascular supplement stack. Its absence does not produce obvious short-term effects but its presence makes the difference between calcium going where you want it and calcium going where you do not.
One interaction worth knowing. Otherwise extremely safe.
Vitamin K2 at supplemental doses in healthy adults has an excellent safety profile. Unlike vitamin K1, which has well-documented interactions with anticoagulant medications including warfarin, MK-7 at the doses used in supplements has a substantially lower impact on coagulation pathways. However, anyone taking anticoagulant medication should consult their prescriber before supplementing any form of vitamin K.
There is no established upper tolerable intake level for vitamin K2 because toxicity has not been observed at doses studied in human trials, which have extended up to 360µg MK-7 daily over extended periods without adverse effects. The 75µg dose in this formula is at the lower end of the range used in clinical research and presents no known risk in healthy adults.
The combination of K2 with D3 and magnesium in The Daily Foundation reflects current best evidence for calcium metabolism support. These three nutrients operate as an integrated system. Magnesium activates vitamin D3. D3 increases calcium absorption. K2 directs the absorbed calcium to bone rather than soft tissue. The formula is designed with these interactions in mind.
K2 is safe. If you take warfarin, speak to your doctor first. For everyone else, the only question is why you were not already taking it.
At a glance
Form
Menaquinone-7 (MK-7)
Dose Per Capsule
12.5µg
Daily Serving
75µg (6 capsules)
NRV
100%
Best Taken
With food containing fat. K2 is fat-soluble.
Works With
Vitamin D3 and Magnesium in The Daily Foundation
What the Research Shows
Cardiovascular
57% reduction in coronary heart disease risk. 52% reduction in severe arterial calcification.
The Rotterdam Study followed nearly 5,000 adults over ten years and found that higher dietary Vitamin K2 intake was associated with a 57% reduction in coronary heart disease mortality, a 52% reduction in severe aortic calcification and a 26% reduction in all-cause mortality. K1 intake showed no such association. The distinction between K1 and K2 is real and it matters.
Bone
Three years of MK-7 reduced bone loss in postmenopausal women.
A three-year randomised controlled trial in Osteoporosis International found that 180µg of MK-7 daily produced significantly less age-related decline in bone mineral density at multiple skeletal sites compared to placebo. The MK-7 group also showed significantly higher carboxylated osteocalcin, confirming the mechanistic pathway directly.
Arteries
MK-7 supplementation measurably reduced arterial stiffness over three years.
A three-year double-blind trial in Thrombosis and Haemostasis measured carotid-femoral pulse wave velocity, a validated marker of arterial calcification, and found significantly reduced arterial stiffness in the MK-7 group versus placebo. Activated Matrix Gla Protein levels were also significantly higher. The mechanism and the outcome measured in the same trial.
MK-7 vs MK-4
At physiological doses only MK-7 produces sustained blood concentration. MK-4 does not.
A human pharmacokinetic study in Blood measured blood K2 levels over 96 hours after dosing with either MK-7 or MK-4. Only MK-7 produced sustained circulating concentrations across the full measurement window. MK-4 produced no measurable elevation at the same physiological doses. Half-life of MK-7 is approximately 72 hours. MK-4 clears in 1 to 2.
Combination logic
D3 increases calcium absorption. K2 decides where that calcium goes. You need both.
Vitamin D3 dramatically increases intestinal calcium absorption. Without adequate K2 to activate osteocalcin and Matrix Gla Protein, the routing decision for that calcium is unresolved. Osteocalcin directs calcium into bone mineral. MGP prevents it depositing in arterial walls and soft tissue. Supplementing D3 without K2 in K2-deficient individuals increases calcium availability without providing the directional signal that determines whether it ends up strengthening your skeleton or calcifying your vasculature. This is the reason both nutrients appear in The Daily Foundation at evidence-supported doses rather than one without the other.
D3 opens the door for calcium. K2 tells it where to go.
