Health Reference LibraryHow much vitamin K2 should I take, and can you take too much?
This entry is part of the Nutri Tailor Health Reference Library — cited research on supplements, nutrients and adjacent areas of health.
Summary
Ninety to two hundred micrograms a day of MK-7 covers what the trials used, and the three year bone study ran at 180 micrograms, so one 150 microgram capsule or the K2 already in a D3 and K2 combination is the whole answer for most people. There is no upper limit, because no harm has been found from high intakes in healthy adults, and the UK figure of about 70 micrograms a day is set for vitamin K as a whole. MK-7 stays in the blood for about three days, so one dose a day is plenty and a missed day does not matter. The one exception is anyone whose blood clotting is managed by their GP.
Dose calculator: capsules to reach your vitamin K2 target
Enter the daily amount of vitamin K2 you are aiming for and see how many servings of each Nutri Tailor product reach it. Nothing you enter leaves this device. No AI is used.
This tool does arithmetic on the label figures. It is not personal dosing advice and it knows nothing about your history or blood results. The reference intake, the safe upper guide and the trial doses are on this page; talk to your GP or a registered nutritional therapist before changing what you take.
Effective dose
The reference intake is about 1 microgram of vitamin K per kilogram of body weight a day in the UK, roughly 70 micrograms for an adult, set for vitamin K as a whole rather than for K2. For most people taking K2 alongside vitamin D3, 90 to 200 micrograms a day of MK-7 covers what the trials used. The three year bone study used 180 micrograms a day; the K2 in most D3 and K2 combinations sits between 50 and 200 micrograms. MK-7 stays in the blood for about three days, so a single daily dose is enough and a missed day does not matter.
Safety profile
How much is too much: no upper limit has been set for vitamin K in the UK or by EFSA, because no harm has been found from high intakes in people whose blood clotting is not being managed by a doctor. Vitamin K is not toxic in the ordinary sense and no amount from a supplement has been shown to harm a healthy adult. The one group who must not add it without a conversation is anyone whose blood clotting is managed by their GP or clinic, because vitamin K works on the same clotting proteins; that decision belongs with them. More than 200 micrograms a day buys nothing extra.
Guideline positions
NHS vitamins and minerals guidance for vitamin K2. NIH Office of Dietary Supplements fact sheet for vitamin K2 where one exists. The trial doses quoted above are from the sources listed on this page.
Practical framework
Capsules to reach the dose, from the Nutri Tailor range, all made in the UK: [vitamin K2 capsules](/products/vitamin-k2), 150 micrograms of MK-7 per capsule, one a day; [vitamin D3 and K2 capsules](/products/vitamin-d3-k2), 200 micrograms of K2 with 2500 IU of D3 per capsule; [vitamin D3 and K2 oil](/products/vitamin-d3-k2-oil), 5 micrograms of K2 per drop, so ten drops give 50 micrograms with 1000 IU of D3. To read your own result against the UK ranges, use the free blood test result interpreter. This is a summary of published research, not personal health advice. Talk to your GP or a registered nutritional therapist before changing what you take, especially if you are pregnant, have a diagnosed condition or are under ongoing care.
Common misconceptions
That more vitamin K2 works faster: above the doses the trials used there is no extra effect, only more side effects. That the front of the bottle states the dose: read the per capsule figure and the serving size on the back. That the NHS figure is a toxic threshold: it is the level below which harm is unlikely, which is a different thing.
Sources
- Knapen MH, Drummen NE, Smit E, Vermeer C, Theuwissen E 2013. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis International. PMID: 23525894
- 2020. Vitamin K. NHS.