Stack Genius ingredient guide
Vitamin K
A fat-soluble vitamin family involved in normal blood clotting and proteins that support bone metabolism.
Overview
Vitamin K is a fat-soluble vitamin the body uses for proteins involved in normal blood clotting and for proteins involved in bone metabolism. It exists in two main natural forms: phylloquinone, often called vitamin K1, and a group of related compounds called menaquinones, often grouped as vitamin K2.
Most people encounter vitamin K through food before they encounter it as a supplement. Vitamin K1 is found in leafy greens and some vegetable oils, while vitamin K2 forms appear in some animal foods and fermented foods. Supplement labels may list vitamin K1, vitamin K2, or a blend, and the form and amount on the Supplement Facts panel matter more than front-label marketing.
For Stack Genius users, vitamin K is a good example of why both diet context and medication context belong in the picture. A person can get meaningful vitamin K from regular meals, from a multivitamin, or from a standalone product, and the medication interaction context with anticoagulants is important enough that it should not be ignored when reviewing a stack.
Key takeaways
- Vitamin K covers two main forms, K1 and K2, and label form and amount matter more than front-label claims.
- Vitamin K intake interacts with warfarin and similar anticoagulant medicines, so consistency and clinician input matter for people on those therapies.
- Leafy greens and other whole foods are a meaningful source of vitamin K, so diet context belongs alongside any supplement review.
Practical guidance
What to know before adding Vitamin K
Evidence snapshot
Vitamin K has a well-established role in normal blood clotting and in proteins involved in bone metabolism. Evidence for specific supplement goals beyond meeting needs depends on baseline intake, form, dose, and the question being asked, and broad marketing claims should be read with that in mind.
Common misunderstanding
People sometimes treat vitamin K1 and vitamin K2 as interchangeable or assume more is always better. The two forms have different food sources and label patterns, and higher supplemental amounts are not automatically more useful, especially when food intake is already reasonable.
Tracking note
Track the exact product, the vitamin K form on the label, the amount per serving, timing, and whether vitamin K also appears in a multivitamin or other product in the routine. Diet context, especially leafy greens, is worth noting because food intake is part of the overall picture.
Safety note
People taking warfarin or other anticoagulant medicines should not change vitamin K intake from supplements or major diet shifts without clinician guidance, because vitamin K intake affects how these medicines work. Pregnancy, medical conditions, and multiple medications are also reasons to involve a qualified healthcare professional.
Dosing & Timing
Vitamin K needs vary by age, sex, and life stage, and many people get meaningful amounts from food, especially leafy greens. For supplements, the most useful label details are the vitamin K form, K1 or K2, and the amount per serving, along with whether vitamin K also appears in a multivitamin or other product in the routine. Vitamin K is fat-soluble, so taking it with a meal that contains some fat is a reasonable default.
Safety and interaction context
The most important safety context for vitamin K is its interaction with warfarin and other anticoagulant medicines. Consistent vitamin K intake matters for people on these therapies, and changes in supplements or diet should be discussed with a qualified clinician. People with medical conditions, pregnancy, or multiple medications should also check vitamin K supplement use with a healthcare professional rather than relying on label marketing.
Additional Forms of Vitamin K
Some supplement labels use more specific form names for the same parent nutrient. Stack Genius groups those forms here so the main ingredient page stays focused while still making the label terms easy to recognize.
- Vitamin K (menadione)
- Vitamin K (menaquinone)
- Vitamin K (Phylloquinone)
- Vitamin K2
Sources
- NIH Office of Dietary Supplements - Vitamin K Fact Sheet for Health ProfessionalsFederal overview of vitamin K forms, functions, intake, and interactions including anticoagulant medicines.
- NIH Office of Dietary Supplements - Vitamin K Consumer Fact SheetConsumer-facing overview of vitamin K roles, food sources, and medication interaction context.