MK-7 is a form of vitamin K2 that activates proteins your body uses to direct calcium where it belongs: into your bones and away from your arteries. It’s one of several types of vitamin K2 (collectively called menaquinones), but MK-7 stands out because it stays active in your bloodstream for about three days, giving it a longer working window than other forms. That extended activity is why it’s become the most popular form of K2 in supplements.
How MK-7 Works in Your Body
MK-7’s core job is simple: it activates certain proteins through a chemical process called carboxylation. Without enough vitamin K2, these proteins float around in an inactive state, unable to do their jobs. Two of these proteins matter most for your health.
The first is osteocalcin, a protein made by bone-building cells. When MK-7 activates osteocalcin, the protein gains the ability to bind calcium and incorporate it into bone mineral. The presence of three specific binding sites on osteocalcin is critical for regulating how bone mineral matures and strengthens. When vitamin K levels are low, a larger share of osteocalcin stays inactive (called uncarboxylated osteocalcin), which researchers use as a marker of vitamin K insufficiency.
The second key protein is called Matrix Gla Protein, or MGP. This protein acts as a calcification inhibitor in your blood vessels. When MK-7 activates MGP, it can bind to calcium in arterial walls and prevent it from forming hard deposits. MGP exists in several forms depending on whether it’s been activated or not, and higher levels of the inactive form are associated with greater arterial calcification.
Effects on Bone Health
Because MK-7 activates osteocalcin, it’s widely promoted for bone strength. Observational studies have consistently linked low vitamin K status (measured by higher levels of inactive osteocalcin) with age-related bone loss. The logic is straightforward: if your osteocalcin isn’t properly activated, calcium doesn’t get incorporated into bone as efficiently.
The clinical trial picture is more complicated. While MK-7 clearly improves the carboxylation of osteocalcin (that’s well established), trials testing whether K2 supplementation actually reduces bone loss or fracture risk in the general population have been mixed. Some show modest improvements in bone mineral density, particularly at the hip and spine, while others show no significant benefit. The current evidence doesn’t strongly support MK-7 supplementation as a standalone strategy for preventing fractures in otherwise healthy people, though it may play a supporting role alongside calcium and vitamin D.
Effects on Heart and Artery Health
The cardiovascular side of MK-7 has generated significant interest. By activating MGP in blood vessel walls, MK-7 helps prevent the calcium buildup that makes arteries stiff and narrow over time. Arterial calcification is a major contributor to heart disease and high blood pressure, especially as you age.
A study in post-menopausal women found that one year of MK-7 supplementation significantly slowed the progression of arterial stiffness compared to placebo. Women taking MK-7 saw their vascular stiffness increase by only about 9%, while the placebo group’s stiffness jumped by roughly 49%. The benefit was most pronounced in women who already had stiffer arteries at the start of the study. In that subgroup, MK-7 improved the flexibility and stretchability of their blood vessels while the placebo group continued to decline. Local pulse wave velocity, a measure of how fast blood pressure waves travel through arteries (faster means stiffer), dropped by about 3% in the MK-7 group with high baseline stiffness.
These results suggest MK-7 may be most useful for people whose arteries are already showing signs of age-related stiffening, rather than as a preventive measure for younger, healthy individuals.
Potential Role in Blood Sugar Control
A randomized controlled trial gave people with type 2 diabetes 200 micrograms of MK-7 daily for 12 weeks. Within the MK-7 group, fasting blood sugar, long-term blood sugar markers (HbA1c), fasting insulin, and insulin resistance all improved significantly. When compared directly to the placebo group after adjusting for baseline differences, fasting blood sugar and HbA1c remained significantly better in the MK-7 group, though the insulin-specific measures didn’t reach statistical significance between groups.
The proposed explanation involves several pathways. Vitamin K appears to reduce oxidative stress and inflammation, raise levels of adiponectin (a hormone that improves insulin sensitivity), and activate cellular energy sensors that help regulate how your body processes both sugar and fat. This is still an early area of research, and most of the evidence comes from people who already have metabolic problems rather than healthy populations.
Food Sources of MK-7
MK-7 is produced by specific bacteria during fermentation, which means your dietary options are limited. The richest source by far is natto, a traditional Japanese dish made from fermented soybeans. A 3-ounce serving of natto provides roughly 850 micrograms of MK-7, which dwarfs any other food source and far exceeds the amounts used in most supplement studies.
Other fermented foods like certain aged cheeses and sauerkraut contain smaller amounts of various menaquinones, but none come close to natto for MK-7 specifically. If you don’t eat natto (and many people outside Japan find its sticky texture and strong flavor unappealing), supplements are the most reliable way to get consistent MK-7 intake. Most clinical trials have used doses between 100 and 200 micrograms per day.
Because vitamin K2 is fat-soluble, you’ll absorb it best when taken with a meal that contains some dietary fat. Taking it on an empty stomach reduces how much actually makes it into your bloodstream.
Who Should Be Cautious
The most important safety consideration with MK-7 involves blood-thinning medications. Warfarin and similar anticoagulants work by blocking vitamin K’s activity, so adding MK-7 to your routine can directly counteract these drugs and change how your blood clots. If you take any anticoagulant medication, your dose of vitamin K needs to stay consistent day to day, and any change, including starting a supplement, requires coordination with whoever manages your medication.
For people not on blood thinners, MK-7 at typical supplement doses (100 to 200 micrograms) has shown a strong safety profile in clinical trials lasting up to a year. No upper intake level has been established for vitamin K by major health authorities, largely because toxicity from food or supplement sources hasn’t been demonstrated in studies.