Best Vitamin K Supplements AI pick
Chosen by an AI model from its trained knowledge, with its reasoning.
AI pick (line): NOW Foods MK-7 Vitamin K-2
It is a plain, single-ingredient MK-7 from a large, widely tested brand, and MK-7 is the long-acting K2 form that works with one small daily dose.
Not for: Anyone taking warfarin or another vitamin K antagonist without their prescriber's approval, and anyone who wants all three K forms in one capsule.
AI picks by need
For K1, MK-4 and MK-7 in one softgel
Life Extension Super K (line)
It is one of the few widely sold formulas that combines the dietary K1 form with both main K2 forms.
Not for: Anyone on anticoagulants, and anyone who only wants a low-dose MK-7.
For K2 combined with vitamin D3
Thorne Vitamin D + K2 (line)
It is a liquid D3 and K2 combination from a brand known for third-party testing, so the dose is easy to adjust drop by drop.
Not for: People who already get enough vitamin D or whose doctor has them on a fixed D3 dose, and anyone on warfarin.
For MK-7 made with branded MenaQ7
Doctor's Best Natural Vitamin K2 MK-7 with MenaQ7 (line)
It names its MK-7 raw material, which tells you the source and the all-trans form.
Not for: Anyone on vitamin K antagonists, and anyone who specifically wants MK-4.
What the AI looks for in Vitamin K Supplements
- Form stated on the label
- The label should say K1 (phylloquinone), K2 as MK-4 (menatetrenone) or K2 as MK-7 (menaquinone-7). A label that only says "vitamin K2" is not enough. The forms behave differently: MK-7 stays in the blood for days, while K1 and MK-4 clear within hours and need larger or more frequent doses.
- Dose suited to the form
- MK-7 is typically dosed in the tens to low hundreds of micrograms per day. MK-4 sold in milligram doses is a separate, high-dose approach. Comparing micrograms across forms is misleading. A low MK-4 dose is not equivalent to the same amount of MK-7.
- All-trans MK-7 source
- Prefer products that state all-trans MK-7 or name a branded raw material such as MenaQ7. Only the trans form is biologically active, and poorly made synthetic MK-7 can contain cis isomers.
- Taken with fat
- Choose oil-based softgels or liquids, or take capsules with a meal that contains fat. Vitamin K is fat-soluble and is poorly absorbed on an empty stomach.
- Anticoagulant interaction
- If you take warfarin or another vitamin K antagonist, do not start or stop vitamin K without your prescriber. This rule does not apply to DOACs in the same way. Changes in vitamin K intake shift INR and how well the drug works.
- Independent testing
- Prefer brands that publish third-party testing or carry a recognised supplement certification. The doses are in micrograms, so labelling and dosing accuracy matter more than with most vitamins.
Brands that matter
- NOW Foods: Plain, simple MK-7 products from a brand that runs its own testing lab.
- Life Extension: Best known for combined K1, MK-4 and MK-7 formulas.
- Thorne: Liquid and capsule D3 + K2 combinations with a strong testing reputation.
- Doctor's Best: MK-7 made with the named MenaQ7 raw material.
- Jarrow Formulas: Long-standing MK-7 products.
- Pure Encapsulations: Hypoallergenic formulas, including K2 and D3/K2 options.
- Sports Research: Popular D3 + K2 softgels in coconut oil.
What to avoid
- Labels that say "K2" without stating whether it is MK-4 or MK-7.
- Starting or stopping any vitamin K product while on warfarin without telling your prescriber.
- High-dose D3 + K2 combinations taken "for bones" by people who were never tested for vitamin D deficiency.
- Gummies and multi-ingredient "bone" blends where the vitamin K form and dose are buried or unclear.
Questions
Should I take K1 or K2?
K1 comes mainly from leafy greens and mostly supports blood clotting in the liver. K2, especially MK-7, is what most bone and heart supplements use because it lasts longer in the body. For general supplementation, most people choose MK-7.
Do I need K2 if I take vitamin D?
It is often paired with D3 because both play a role in calcium handling. However, evidence that the combination is required is limited, so take it as an optional pairing rather than a necessity.
Vitamin K1 Supplements
Most people get enough K1 from leafy greens, so a K1-only supplement is rarely needed. If you want K1 included, the combined K1, MK-4 and MK-7 formula above (Life Extension Super K) covers it, and the warfarin warning applies even more strongly to K1.