Vitamin K1 (Phylloquinone): Intake, Bone Trials, Warfarin
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Vitamin K1 (Phylloquinone): half-life, strengths and approval status

Adequate intake and amounts studied · Approval status · Half-life notes

What is Vitamin K1?

Vitamin K1, or phylloquinone, is the main form of vitamin K in food, found mostly in green leafy vegetables. The body needs vitamin K to make blood-clotting proteins and some bone proteins. Vitamin K2 (menaquinones) is a related group with its own page.

Also known as: vitamin K, phylloquinone, phytonadione, phytomenadione.

Reference intakes

ODS lists Adequate Intakes of 90 to 120 mcg a day for adults, depending on sex. Bone trials used 500 mcg a day for 3 years (Booth 2008) and 5 mg a day for 2 to 4 years (Cheung 2008). These are study protocols, not a recommendation.

Approval status and how it is used

The NIH Dietary Supplement Label Database lists vitamin K1 products such as Vitamin K1 100 mcg from Swanson as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. Phytonadione, the drug name for vitamin K1, is also an FDA-approved prescription drug (Drugs@FDA). ODS says most people in the US get enough vitamin K from food; severe deficiency, which causes bleeding, is very rare in healthy adults. Newborns not given vitamin K at birth and people with problems absorbing fat or who have had bariatric surgery are more at risk.

What studies show: ODS says it is not clear whether vitamin K supplements affect osteoporosis risk. In 452 adults aged 60 to 80 taking calcium and vitamin D, 500 mcg a day of K1 for 3 years did not change bone density (Booth 2008). In 440 postmenopausal women with low bone density, 5 mg a day for 2 to 4 years did not change bone density either; fewer women on K1 had fractures (9 versus 20), but the trial was not designed to test fractures (Cheung 2008). ODS says trials on vitamin K and artery calcification have been inconclusive.

Safety, per ODS: there is no upper limit because vitamin K has a low potential for toxicity. Warfarin (Coumadin) and similar blood thinners work against vitamin K, so people taking them need to keep their vitamin K intake steady. Antibiotics, bile acid sequestrants and orlistat can lower vitamin K levels.

Vitamin K1 half-life and time to peak

  • Half-lifeNot listed
  • Time to peak (Tmax)Not listed

We could not find a single published half-life or time to peak for vitamin K1 that applies to a supplement dose, so we do not list one. ODS says vitamin K is quickly broken down and excreted, so only low levels are found in blood and tissues.

How to track Vitamin K1 in Dose Track

  1. Add Vitamin K1 as a custom compound. Start typing its name and Dose Track fills in the details from its research library for you to check, and it sits next to everything else you take.
  2. Log each dose when you take it so your history shows exactly what you took and when.
  3. Set reminders on your own schedule, whether that is daily, weekly or every few days.
  4. Your log is stored on your phone and no account is needed. Data only leaves it for features you choose, like AI answers and lab reading.

How Dose Track handles peptides · Reconstitution calculator · Half-life calculator

Vitamin K2 (MK-7)menaquinone-7, MK-7 · half-life about 3 days Vitamin D3 (Cholecalciferol)cholecalciferol · half-life about 15 days Calciumcalcium carbonate, calcium citrate

Frequently asked questions

What is the half-life of Vitamin K1?+
We could not find a single published half-life or time to peak for vitamin K1 that applies to a supplement dose, so we do not list one. ODS says vitamin K is quickly broken down and excreted, so only low levels are found in blood and tissues.
Can I take vitamin K1 with warfarin?+
ODS says warfarin works against vitamin K, so people on it need to keep vitamin K intake consistent. Talk to the clinician managing your warfarin before changing it.
Does vitamin K1 help bones?+
Two multi-year trials found no change in bone density. One found fewer fractures with 5 mg a day, but it was not designed to test fractures, and ODS says the effect on osteoporosis is unclear.
Can I track Vitamin K1 in Dose Track?+
Yes. Vitamin K1 is in Dose Track's research library, so when you add it as a custom compound its details are filled in for you to check. You can then log each dose next to your other compounds, set reminders on your own schedule, and see your history next to your lab results. Your log is stored on your phone and no account is needed. Data only leaves it for features you choose, like AI answers and lab reading.

Sources

  1. NIH Office of Dietary Supplements. Vitamin K fact sheet for health professionals (updated October 22, 2026).
  2. Booth SL, et al. Effect of vitamin K supplementation on bone loss in elderly men and women. J Clin Endocrinol Metab. 2008;93(4):1217-1223.
  3. Cheung AM, et al. Vitamin K supplementation in postmenopausal women with osteopenia (ECKO trial): a randomized controlled trial. PLoS Med. 2008;5(10):e196.
  4. FDA. Drugs@FDA database of approved drugs (searched October 28, 2026).
  5. NIH ODS Dietary Supplement Label Database. Vitamin K1 100 mcg (Swanson), dietary supplement label, entered March 22, 2024; checked October 28, 2026.
  6. FDA. Questions and answers on dietary supplements.

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