Most people supplementing vitamin K2 take between 100 and 200 mcg per day of the MK-7 form, which is the most common type sold in supplements. There is no official recommended daily allowance specifically for K2, though. Government nutrition guidelines lump K1 and K2 together under a single “adequate intake” for total vitamin K, which sits at 120 mcg per day for adult men and 90 mcg for adult women. That number is based almost entirely on K1 from leafy greens, leaving K2 dosing in the hands of clinical research rather than formal policy.
Why There’s No Official K2 Dose
The NIH’s Food and Nutrition Board found insufficient data to set a specific requirement for vitamin K2 (the menaquinone family) apart from vitamin K1 (phylloquinone). The adequate intakes they published apply to vitamin K as a whole and are set at levels observed in generally healthy populations. Because most Western diets are dominated by K1 from vegetables, the guideline doesn’t tell you much about how much K2 you actually need.
This gap means the dosing numbers that circulate online come from clinical trials, not government recommendations. Those trials have tested a wide range of doses depending on the form of K2 and the health outcome being studied.
MK-7 vs. MK-4: Two Very Different Dose Ranges
Vitamin K2 isn’t a single compound. It’s a family of molecules that differ in chain length, and the two you’ll encounter in supplements are MK-7 and MK-4. They behave differently in your body, which is why their effective doses are so far apart.
MK-7, typically derived from fermented soybeans (natto), has a half-life of roughly 72 hours. That means it stays in your bloodstream for days after a single dose, building up steady levels with daily use. Clinical studies on heart and bone health generally use doses in the range of 100 to 360 mcg per day. A narrative review in the journal Open Heart noted that 180 to 360 mcg per day of longer-chain menaquinones (MK-7, MK-8, MK-9) showed cardiovascular benefits. Most retail supplements land at 100 or 200 mcg of MK-7, which falls at or just below this range.
MK-4 is a different story. It has a half-life of only a few hours, clears the bloodstream quickly, and requires far larger doses to have measurable effects. Japanese clinical trials on osteoporosis have used 45 mg per day, which is 45,000 mcg. A study in postmenopausal women with fractures found that even a more moderate dose of 5 mg per day was enough to bring a key bone protein marker back to levels typical of healthy premenopausal women. Still, 5 mg of MK-4 is roughly 25 to 50 times the dose you’d take of MK-7, which is why the two forms aren’t interchangeable at the same dose.
Dosing by Health Goal
General Maintenance
If you’re supplementing as a general health measure alongside vitamin D, 100 to 200 mcg of MK-7 per day is the most commonly used range. This is what most standalone K2 supplements and combination D3/K2 products contain.
Bone Health
Studies on bone density and fracture risk have used either 100 to 200 mcg of MK-7 or the much higher 45 mg of MK-4. If you’re using MK-7 for bone support, staying in the 100 to 200 mcg range is reasonable. MK-4 at therapeutic bone doses (5 to 45 mg) is a fundamentally different supplementation strategy and is sometimes used under medical supervision in countries like Japan.
Cardiovascular Support
Research on reducing arterial stiffness and calcification points toward 180 to 360 mcg per day of MK-7 or similar long-chain forms. If cardiovascular health is your primary concern, the higher end of standard MK-7 dosing (200 mcg or above) aligns better with the evidence.
Food Sources and What They Provide
You can get meaningful amounts of K2 from certain foods, though the richest source is one most Westerners don’t eat. A single tablespoon of natto (a Japanese fermented soybean dish) contains about 150 mcg of K2, almost entirely as MK-7. That one tablespoon roughly matches a standard supplement capsule.
Cheese is the most common dietary source in Western diets, but the amounts are more modest. Per 50-gram serving (a little under 2 ounces):
- Munster: about 50 mcg
- Camembert: about 34 mcg
- Edam or aged Gouda: about 32 mcg
- Cheddar: about 12 mcg
The K2 in cheese is a mix of several menaquinone forms produced by bacteria during fermentation. Harder, longer-aged cheeses tend to contain more. Egg yolks and dark-meat poultry also contribute small amounts, primarily as MK-4.
Safety and Upper Limits
No tolerable upper intake level has been established for any form of vitamin K, including K2. The NIH notes that toxicity from vitamin K in food or supplements has not been well documented in the general population. Even the 45 mg MK-4 doses used in Japanese bone trials have not shown significant adverse effects in those study populations.
The major exception involves blood-thinning medications. Even very low doses of MK-7, as little as 10 mcg per day, can measurably shift clotting markers in people taking anticoagulants. A study in healthy volunteers on blood thinners found that 10 mcg of MK-7 caused clinically relevant changes in clotting time in about 40% of participants, and 20 mcg affected roughly 60%. If you take a blood thinner, K2 supplementation at any dose is something to discuss with whoever manages your medication.
Getting the Most From Your Supplement
Vitamin K2 is fat-soluble, meaning it absorbs significantly better when taken with a meal that contains some dietary fat. Taking it on an empty stomach or with a fat-free meal reduces how much actually reaches your bloodstream. A meal with eggs, cheese, nuts, olive oil, or avocado provides more than enough fat to support absorption.
Because MK-7 has a long half-life of about three days, timing is forgiving. A single daily dose with any fat-containing meal keeps blood levels stable. MK-4, with its short half-life of just a few hours, is sometimes split into multiple doses throughout the day in clinical settings, but this is mainly relevant at the high therapeutic doses used for bone disease rather than for general supplementation.